version 1.14, 1995/04/20 09:42:52
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version 1.17, 1995/09/15 14:52:51
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@comment The source is gforth.ds, from which gforth.texi is generated |
@comment The source is gforth.ds, from which gforth.texi is generated |
@comment %**start of header (This is for running Texinfo on a region.) |
@comment %**start of header (This is for running Texinfo on a region.) |
@setfilename gforth.info |
@setfilename gforth.info |
@settitle GNU Forth Manual |
@settitle Gforth Manual |
@comment @setchapternewpage odd |
@comment @setchapternewpage odd |
@comment %**end of header (This is for running Texinfo on a region.) |
@comment %**end of header (This is for running Texinfo on a region.) |
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@ifinfo |
@ifinfo |
This file documents GNU Forth 0.0 |
This file documents Gforth 0.1 |
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Copyright @copyright{} 1994 GNU Forth Development Group |
Copyright @copyright{} 1994 Gforth Development Group |
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Permission is granted to make and distribute verbatim copies of |
Permission is granted to make and distribute verbatim copies of |
this manual provided the copyright notice and this permission notice |
this manual provided the copyright notice and this permission notice |
Line 38 Copyright @copyright{} 1994 GNU Forth De
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Line 38 Copyright @copyright{} 1994 GNU Forth De
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@titlepage |
@titlepage |
@sp 10 |
@sp 10 |
@center @titlefont{GNU Forth Manual} |
@center @titlefont{Gforth Manual} |
@sp 2 |
@sp 2 |
@center for version 0.0 |
@center for version 0.1 |
@sp 2 |
@sp 2 |
@center Anton Ertl |
@center Anton Ertl |
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@sp 3 |
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@center This manual is under construction |
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@comment The following two commands start the copyright page. |
@comment The following two commands start the copyright page. |
@page |
@page |
@vskip 0pt plus 1filll |
@vskip 0pt plus 1filll |
Copyright @copyright{} 1994 GNU Forth Development Group |
Copyright @copyright{} 1994 Gforth Development Group |
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@comment !! Published by ... or You can get a copy of this manual ... |
@comment !! Published by ... or You can get a copy of this manual ... |
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Line 72 Copyright @copyright{} 1994 GNU Forth De
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Line 74 Copyright @copyright{} 1994 GNU Forth De
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@node Top, License, (dir), (dir) |
@node Top, License, (dir), (dir) |
@ifinfo |
@ifinfo |
GNU Forth is a free implementation of ANS Forth available on many |
Gforth is a free implementation of ANS Forth available on many |
personal machines. This manual corresponds to version 0.0. |
personal machines. This manual corresponds to version 0.0. |
@end ifinfo |
@end ifinfo |
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@menu |
@menu |
* License:: |
* License:: |
* Goals:: About the GNU Forth Project |
* Goals:: About the Gforth Project |
* Other Books:: Things you might want to read |
* Other Books:: Things you might want to read |
* Invocation:: Starting GNU Forth |
* Invocation:: Starting Gforth |
* Words:: Forth words available in GNU Forth |
* Words:: Forth words available in Gforth |
* ANS conformance:: Implementation-defined options etc. |
* ANS conformance:: Implementation-defined options etc. |
* Model:: The abstract machine of GNU Forth |
* Model:: The abstract machine of Gforth |
* Emacs and GForth:: The GForth Mode |
* Emacs and Gforth:: The Gforth Mode |
* Internals:: Implementation details |
* Internals:: Implementation details |
* Bugs:: How to report them |
* Bugs:: How to report them |
* Pedigree:: Ancestors of GNU Forth |
* Pedigree:: Ancestors of Gforth |
* Word Index:: An item for each Forth word |
* Word Index:: An item for each Forth word |
* Node Index:: An item for each node |
* Node Index:: An item for each node |
@end menu |
@end menu |
Line 98 personal machines. This manual correspon
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Line 100 personal machines. This manual correspon
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@iftex |
@iftex |
@unnumbered Preface |
@unnumbered Preface |
This manual documents GNU Forth. The reader is expected to know |
This manual documents Gforth. The reader is expected to know |
Forth. This manual is primarily a reference manual. @xref{Other Books} |
Forth. This manual is primarily a reference manual. @xref{Other Books} |
for introductory material. |
for introductory material. |
@end iftex |
@end iftex |
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@node Goals, Other Books, License, Top |
@node Goals, Other Books, License, Top |
@comment node-name, next, previous, up |
@comment node-name, next, previous, up |
@chapter Goals of GNU Forth |
@chapter Goals of Gforth |
@cindex Goals |
@cindex Goals |
The goal of the GNU Forth Project is to develop a standard model for |
The goal of the Gforth Project is to develop a standard model for |
ANSI Forth. This can be split into several subgoals: |
ANSI Forth. This can be split into several subgoals: |
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@itemize @bullet |
@itemize @bullet |
@item |
@item |
GNU Forth should conform to the ANSI Forth standard. |
Gforth should conform to the ANSI Forth standard. |
@item |
@item |
It should be a model, i.e. it should define all the |
It should be a model, i.e. it should define all the |
implementation-dependent things. |
implementation-dependent things. |
Line 121 It should become standard, i.e. widely a
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Line 123 It should become standard, i.e. widely a
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is the most difficult one. |
is the most difficult one. |
@end itemize |
@end itemize |
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To achieve these goals GNU Forth should be |
To achieve these goals Gforth should be |
@itemize @bullet |
@itemize @bullet |
@item |
@item |
Similar to previous models (fig-Forth, F83) |
Similar to previous models (fig-Forth, F83) |
Line 137 Free.
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Line 139 Free.
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Available on many machines/easy to port. |
Available on many machines/easy to port. |
@end itemize |
@end itemize |
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Have we achieved these goals? GNU Forth conforms to the ANS Forth |
Have we achieved these goals? Gforth conforms to the ANS Forth |
standard; it may be considered a model, but we have not yet documented |
standard. It may be considered a model, but we have not yet documented |
which parts of the model are stable and which parts we are likely to |
which parts of the model are stable and which parts we are likely to |
change; it certainly has not yet become a de facto standard. It has some |
change. It certainly has not yet become a de facto standard. It has some |
similarities and some differences to previous models; It has some |
similarities and some differences to previous models. It has some |
powerful features, but not yet everything that we envisioned; on RISCs |
powerful features, but not yet everything that we envisioned. We |
it is as fast as interpreters programmed in assembly, on |
certainly have achieved our execution speed goals (@pxref{Performance}). |
register-starved machines it is not so fast, but still faster than any |
It is free and available on many machines. |
other C-based interpretive implementation; it is free and available on |
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many machines. |
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@node Other Books, Invocation, Goals, Top |
@node Other Books, Invocation, Goals, Top |
@chapter Other books on ANS Forth |
@chapter Other books on ANS Forth |
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As the standard is relatively new, there are not many books out yet. It |
As the standard is relatively new, there are not many books out yet. It |
is not recommended to learn Forth by using GNU Forth and a book that is |
is not recommended to learn Forth by using Gforth and a book that is |
not written for ANS Forth, as you will not know your mistakes from the |
not written for ANS Forth, as you will not know your mistakes from the |
deviations of the book. |
deviations of the book. |
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Line 173 other languages should find it ok.
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Line 173 other languages should find it ok.
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@chapter Invocation |
@chapter Invocation |
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You will usually just say @code{gforth}. In many other cases the default |
You will usually just say @code{gforth}. In many other cases the default |
GNU Forth image will be invoked like this: |
Gforth image will be invoked like this: |
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@example |
@example |
gforth [files] [-e forth-code] |
gforth [files] [-e forth-code] |
Line 285 that has become a de-facto standard for
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Line 285 that has become a de-facto standard for
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@table @var |
@table @var |
@item word |
@item word |
The name of the word. BTW, GNU Forth is case insensitive, so you can |
The name of the word. BTW, Gforth is case insensitive, so you can |
type the words in in lower case (However, @pxref{core-idef}). |
type the words in in lower case (However, @pxref{core-idef}). |
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@item Stack effect |
@item Stack effect |
Line 293 The stack effect is written in the notat
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Line 293 The stack effect is written in the notat
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@var{after}}, where @var{before} and @var{after} describe the top of |
@var{after}}, where @var{before} and @var{after} describe the top of |
stack entries before and after the execution of the word. The rest of |
stack entries before and after the execution of the word. The rest of |
the stack is not touched by the word. The top of stack is rightmost, |
the stack is not touched by the word. The top of stack is rightmost, |
i.e., a stack sequence is written as it is typed in. Note that GNU Forth |
i.e., a stack sequence is written as it is typed in. Note that Gforth |
uses a separate floating point stack, but a unified stack |
uses a separate floating point stack, but a unified stack |
notation. Also, return stack effects are not shown in @var{stack |
notation. Also, return stack effects are not shown in @var{stack |
effect}, but in @var{Description}. The name of a stack item describes |
effect}, but in @var{Description}. The name of a stack item describes |
Line 409 doc-sm/rem
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Line 409 doc-sm/rem
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@node Double precision, Floating Point, Mixed precision, Arithmetic |
@node Double precision, Floating Point, Mixed precision, Arithmetic |
@subsection Double precision |
@subsection Double precision |
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The outer (aka text) interpreter converts numbers containing a dot into |
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a double precision number. Note that only numbers with the dot as last |
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character are standard-conforming. |
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doc-d+ |
doc-d+ |
doc-d- |
doc-d- |
doc-dnegate |
doc-dnegate |
Line 419 doc-dmax
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Line 424 doc-dmax
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@node Floating Point, , Double precision, Arithmetic |
@node Floating Point, , Double precision, Arithmetic |
@subsection Floating Point |
@subsection Floating Point |
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The format of floating point numbers recognized by the outer (aka text) |
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interpreter is: a signed decimal number, possibly containing a decimal |
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point (@code{.}), followed by @code{E} or @code{e}, optionally followed |
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by a signed integer (the exponent). E.g., @code{1e} ist the same as |
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@code{+1.0e+1}. Note that a number without @code{e} |
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is not interpreted as floating-point number, but as double (if the |
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number contains a @code{.}) or single precision integer. Also, |
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conversions between string and floating point numbers always use base |
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10, irrespective of the value of @code{BASE}. If @code{BASE} contains a |
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value greater then 14, the @code{E} may be interpreted as digit and the |
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number will be interpreted as integer, unless it has a signed exponent |
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(both @code{+} and @code{-} are allowed as signs). |
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Angles in floating point operations are given in radians (a full circle |
Angles in floating point operations are given in radians (a full circle |
has 2 pi radians). Note, that gforth has a separate floating point |
has 2 pi radians). Note, that Gforth has a separate floating point |
stack, but we use the unified notation. |
stack, but we use the unified notation. |
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Floating point numbers have a number of unpleasant surprises for the |
Floating point numbers have a number of unpleasant surprises for the |
Line 468 doc-fatanh
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Line 486 doc-fatanh
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@node Stack Manipulation, Memory access, Arithmetic, Words |
@node Stack Manipulation, Memory access, Arithmetic, Words |
@section Stack Manipulation |
@section Stack Manipulation |
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gforth has a data stack (aka parameter stack) for characters, cells, |
Gforth has a data stack (aka parameter stack) for characters, cells, |
addresses, and double cells, a floating point stack for floating point |
addresses, and double cells, a floating point stack for floating point |
numbers, a return stack for storing the return addresses of colon |
numbers, a return stack for storing the return addresses of colon |
definitions and other data, and a locals stack for storing local |
definitions and other data, and a locals stack for storing local |
Line 594 must only occur at specific addresses; e
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Line 612 must only occur at specific addresses; e
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accessed at addresses divisible by 4. Even if a machine allows unaligned |
accessed at addresses divisible by 4. Even if a machine allows unaligned |
accesses, it can usually perform aligned accesses faster. |
accesses, it can usually perform aligned accesses faster. |
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For the performance-concious: alignment operations are usually only |
For the performance-conscious: alignment operations are usually only |
necessary during the definition of a data structure, not during the |
necessary during the definition of a data structure, not during the |
(more frequent) accesses to it. |
(more frequent) accesses to it. |
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Line 604 char-aligned have no use in the standard
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Line 622 char-aligned have no use in the standard
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created. |
created. |
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The standard guarantees that addresses returned by @code{CREATE}d words |
The standard guarantees that addresses returned by @code{CREATE}d words |
are cell-aligned; in addition, gforth guarantees that these addresses |
are cell-aligned; in addition, Gforth guarantees that these addresses |
are aligned for all purposes. |
are aligned for all purposes. |
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Note that the standard defines a word @code{char}, which has nothing to |
Note that the standard defines a word @code{char}, which has nothing to |
Line 834 FOR
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Line 852 FOR
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NEXT |
NEXT |
@end example |
@end example |
This is the preferred loop of native code compiler writers who are too |
This is the preferred loop of native code compiler writers who are too |
lazy to optimize @code{?DO} loops properly. In GNU Forth, this loop |
lazy to optimize @code{?DO} loops properly. In Gforth, this loop |
iterates @var{n+1} times; @code{i} produces values starting with @var{n} |
iterates @var{n+1} times; @code{i} produces values starting with @var{n} |
and ending with 0. Other Forth systems may behave differently, even if |
and ending with 0. Other Forth systems may behave differently, even if |
they support @code{FOR} loops. |
they support @code{FOR} loops. |
Line 845 they support @code{FOR} loops.
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Line 863 they support @code{FOR} loops.
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ANS Forth permits and supports using control structures in a non-nested |
ANS Forth permits and supports using control structures in a non-nested |
way. Information about incomplete control structures is stored on the |
way. Information about incomplete control structures is stored on the |
control-flow stack. This stack may be implemented on the Forth data |
control-flow stack. This stack may be implemented on the Forth data |
stack, and this is what we have done in gforth. |
stack, and this is what we have done in Gforth. |
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An @i{orig} entry represents an unresolved forward branch, a @i{dest} |
An @i{orig} entry represents an unresolved forward branch, a @i{dest} |
entry represents a backward branch target. A few words are the basis for |
entry represents a backward branch target. A few words are the basis for |
Line 861 doc-again
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Line 879 doc-again
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doc-cs-pick |
doc-cs-pick |
doc-cs-roll |
doc-cs-roll |
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On many systems control-flow stack items take one word, in gforth they |
On many systems control-flow stack items take one word, in Gforth they |
currently take three (this may change in the future). Therefore it is a |
currently take three (this may change in the future). Therefore it is a |
really good idea to manipulate the control flow stack with |
really good idea to manipulate the control flow stack with |
@code{cs-pick} and @code{cs-roll}, not with data stack manipulation |
@code{cs-pick} and @code{cs-roll}, not with data stack manipulation |
Line 951 necessary to define them.
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Line 969 necessary to define them.
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@subsection Calls and returns |
@subsection Calls and returns |
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A definition can be called simply be writing the name of the |
A definition can be called simply be writing the name of the |
definition. When the end of the definition is reached, it returns. An earlier return can be forced using |
definition. When the end of the definition is reached, it returns. An |
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earlier return can be forced using |
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doc-exit |
doc-exit |
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Line 977 locals wordset, but also our own, more p
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Line 996 locals wordset, but also our own, more p
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implemented the ANS Forth locals wordset through our locals wordset). |
implemented the ANS Forth locals wordset through our locals wordset). |
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@menu |
@menu |
* gforth locals:: |
* Gforth locals:: |
* ANS Forth locals:: |
* ANS Forth locals:: |
@end menu |
@end menu |
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@node gforth locals, ANS Forth locals, Locals, Locals |
@node Gforth locals, ANS Forth locals, Locals, Locals |
@subsection gforth locals |
@subsection Gforth locals |
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Locals can be defined with |
Locals can be defined with |
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Line 1025 The name of the local may be preceded by
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Line 1044 The name of the local may be preceded by
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Ar Bi f* Ai Br f* f+ ; |
Ar Bi f* Ai Br f* f+ ; |
@end example |
@end example |
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GNU Forth currently supports cells (@code{W:}, @code{W^}), doubles |
Gforth currently supports cells (@code{W:}, @code{W^}), doubles |
(@code{D:}, @code{D^}), floats (@code{F:}, @code{F^}) and characters |
(@code{D:}, @code{D^}), floats (@code{F:}, @code{F^}) and characters |
(@code{C:}, @code{C^}) in two flavours: a value-flavoured local (defined |
(@code{C:}, @code{C^}) in two flavours: a value-flavoured local (defined |
with @code{W:}, @code{D:} etc.) produces its value and can be changed |
with @code{W:}, @code{D:} etc.) produces its value and can be changed |
Line 1045 locals are initialized with values from
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Line 1064 locals are initialized with values from
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Currently there is no way to define locals with user-defined data |
Currently there is no way to define locals with user-defined data |
structures, but we are working on it. |
structures, but we are working on it. |
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GNU Forth allows defining locals everywhere in a colon definition. This |
Gforth allows defining locals everywhere in a colon definition. This |
poses the following questions: |
poses the following questions: |
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@menu |
@menu |
Line 1055 poses the following questions:
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Line 1074 poses the following questions:
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* Implementation:: |
* Implementation:: |
@end menu |
@end menu |
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@node Where are locals visible by name?, How long do locals live?, gforth locals, gforth locals |
@node Where are locals visible by name?, How long do locals live?, Gforth locals, Gforth locals |
@subsubsection Where are locals visible by name? |
@subsubsection Where are locals visible by name? |
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Basically, the answer is that locals are visible where you would expect |
Basically, the answer is that locals are visible where you would expect |
Line 1177 If the @code{BEGIN} is not reachable fro
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Line 1196 If the @code{BEGIN} is not reachable fro
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@code{AHEAD} or @code{EXIT}), the compiler cannot even make an |
@code{AHEAD} or @code{EXIT}), the compiler cannot even make an |
optimistic guess, as the locals visible after the @code{BEGIN} may be |
optimistic guess, as the locals visible after the @code{BEGIN} may be |
defined later. Therefore, the compiler assumes that no locals are |
defined later. Therefore, the compiler assumes that no locals are |
visible after the @code{BEGIN}. However, the useer can use |
visible after the @code{BEGIN}. However, the user can use |
@code{ASSUME-LIVE} to make the compiler assume that the same locals are |
@code{ASSUME-LIVE} to make the compiler assume that the same locals are |
visible at the BEGIN as at the point where the item was created. |
visible at the BEGIN as at the point where the top control-flow stack |
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item was created. |
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doc-assume-live |
doc-assume-live |
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Line 1213 WHILE
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Line 1233 WHILE
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REPEAT |
REPEAT |
@end example |
@end example |
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@node How long do locals live?, Programming Style, Where are locals visible by name?, gforth locals |
@node How long do locals live?, Programming Style, Where are locals visible by name?, Gforth locals |
@subsubsection How long do locals live? |
@subsubsection How long do locals live? |
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The right answer for the lifetime question would be: A local lives at |
The right answer for the lifetime question would be: A local lives at |
Line 1227 languages (e.g., C): The local lives onl
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Line 1247 languages (e.g., C): The local lives onl
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afterwards its address is invalid (and programs that access it |
afterwards its address is invalid (and programs that access it |
afterwards are erroneous). |
afterwards are erroneous). |
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@node Programming Style, Implementation, How long do locals live?, gforth locals |
@node Programming Style, Implementation, How long do locals live?, Gforth locals |
@subsubsection Programming Style |
@subsubsection Programming Style |
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The freedom to define locals anywhere has the potential to change |
The freedom to define locals anywhere has the potential to change |
Line 1241 write the items in the order you want.
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Line 1261 write the items in the order you want.
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This seems a little far-fetched and eliminating stack manipulations is |
This seems a little far-fetched and eliminating stack manipulations is |
unlikely to become a conscious programming objective. Still, the number |
unlikely to become a conscious programming objective. Still, the number |
of stack manipulations will be reduced dramatically if local variables |
of stack manipulations will be reduced dramatically if local variables |
are used liberally (e.g., compare @code{max} in @ref{gforth locals} with |
are used liberally (e.g., compare @code{max} in @ref{Gforth locals} with |
a traditional implementation of @code{max}). |
a traditional implementation of @code{max}). |
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This shows one potential benefit of locals: making Forth programs more |
This shows one potential benefit of locals: making Forth programs more |
Line 1296 are initialized with the right value for
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Line 1316 are initialized with the right value for
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Here it is clear from the start that @code{s1} has a different value |
Here it is clear from the start that @code{s1} has a different value |
in every loop iteration. |
in every loop iteration. |
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@node Implementation, , Programming Style, gforth locals |
@node Implementation, , Programming Style, Gforth locals |
@subsubsection Implementation |
@subsubsection Implementation |
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GNU Forth uses an extra locals stack. The most compelling reason for |
Gforth uses an extra locals stack. The most compelling reason for |
this is that the return stack is not float-aligned; using an extra stack |
this is that the return stack is not float-aligned; using an extra stack |
also eliminates the problems and restrictions of using the return stack |
also eliminates the problems and restrictions of using the return stack |
as locals stack. Like the other stacks, the locals stack grows toward |
as locals stack. Like the other stacks, the locals stack grows toward |
Line 1334 area and @code{@}} switches it back and
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Line 1354 area and @code{@}} switches it back and
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initializing code. @code{W:} etc.@ are normal defining words. This |
initializing code. @code{W:} etc.@ are normal defining words. This |
special area is cleared at the start of every colon definition. |
special area is cleared at the start of every colon definition. |
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A special feature of GNU Forths dictionary is used to implement the |
A special feature of Gforth's dictionary is used to implement the |
definition of locals without type specifiers: every wordlist (aka |
definition of locals without type specifiers: every wordlist (aka |
vocabulary) has its own methods for searching |
vocabulary) has its own methods for searching |
etc. (@pxref{Wordlists}). For the present purpose we defined a wordlist |
etc. (@pxref{Wordlists}). For the present purpose we defined a wordlist |
Line 1424 this may lead to increased space needs f
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Line 1444 this may lead to increased space needs f
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usually less than reclaiming this space would cost in code size. |
usually less than reclaiming this space would cost in code size. |
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@node ANS Forth locals, , gforth locals, Locals |
@node ANS Forth locals, , Gforth locals, Locals |
@subsection ANS Forth locals |
@subsection ANS Forth locals |
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The ANS Forth locals wordset does not define a syntax for locals, but |
The ANS Forth locals wordset does not define a syntax for locals, but |
words that make it possible to define various syntaxes. One of the |
words that make it possible to define various syntaxes. One of the |
possible syntaxes is a subset of the syntax we used in the gforth locals |
possible syntaxes is a subset of the syntax we used in the Gforth locals |
wordset, i.e.: |
wordset, i.e.: |
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@example |
@example |
Line 1445 restrictions are:
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Line 1465 restrictions are:
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@itemize @bullet |
@itemize @bullet |
@item |
@item |
Locals can only be cell-sized values (no type specifers are allowed). |
Locals can only be cell-sized values (no type specifiers are allowed). |
@item |
@item |
Locals can be defined only outside control structures. |
Locals can be defined only outside control structures. |
@item |
@item |
Locals can interfere with explicit usage of the return stack. For the |
Locals can interfere with explicit usage of the return stack. For the |
exact (and long) rules, see the standard. If you don't use return stack |
exact (and long) rules, see the standard. If you don't use return stack |
accessing words in a definition using locals, you will we all right. The |
accessing words in a definition using locals, you will be all right. The |
purpose of this rule is to make locals implementation on the return |
purpose of this rule is to make locals implementation on the return |
stack easier. |
stack easier. |
@item |
@item |
Line 1462 Locals defined in this way behave like @
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Line 1482 Locals defined in this way behave like @
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(@xref{Values}). I.e., they are initialized from the stack. Using their |
(@xref{Values}). I.e., they are initialized from the stack. Using their |
name produces their value. Their value can be changed using @code{TO}. |
name produces their value. Their value can be changed using @code{TO}. |
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Since this syntax is supported by gforth directly, you need not do |
Since this syntax is supported by Gforth directly, you need not do |
anything to use it. If you want to port a program using this syntax to |
anything to use it. If you want to port a program using this syntax to |
another ANS Forth system, use @file{anslocal.fs} to implement the syntax |
another ANS Forth system, use @file{anslocal.fs} to implement the syntax |
on the other system. |
on the other system. |
Line 1477 doc-(local)
|
Line 1497 doc-(local)
|
|
|
The ANS Forth locals extension wordset defines a syntax, but it is so |
The ANS Forth locals extension wordset defines a syntax, but it is so |
awful that we strongly recommend not to use it. We have implemented this |
awful that we strongly recommend not to use it. We have implemented this |
syntax to make porting to gforth easy, but do not document it here. The |
syntax to make porting to Gforth easy, but do not document it here. The |
problem with this syntax is that the locals are defined in an order |
problem with this syntax is that the locals are defined in an order |
reversed with respect to the standard stack comment notation, making |
reversed with respect to the standard stack comment notation, making |
programs harder to read, and easier to misread and miswrite. The only |
programs harder to read, and easier to misread and miswrite. The only |
Line 1551 doc-printdebugline
|
Line 1571 doc-printdebugline
|
|
|
It is a good idea to make your programs self-checking, in particular, if |
It is a good idea to make your programs self-checking, in particular, if |
you use an assumption (e.g., that a certain field of a data structure is |
you use an assumption (e.g., that a certain field of a data structure is |
never zero) that may become wrong during maintenance. GForth supports |
never zero) that may become wrong during maintenance. Gforth supports |
assertions for this purpose. They are used like this: |
assertions for this purpose. They are used like this: |
|
|
@example |
@example |
Line 1574 debugging, we want more checking, in pro
|
Line 1594 debugging, we want more checking, in pro
|
for speed. Therefore, assertions can be turned off, i.e., the assertion |
for speed. Therefore, assertions can be turned off, i.e., the assertion |
becomes a comment. Depending on the importance of an assertion and the |
becomes a comment. Depending on the importance of an assertion and the |
time it takes to check it, you may want to turn off some assertions and |
time it takes to check it, you may want to turn off some assertions and |
keep others turned on. GForth provides several levels of assertions for |
keep others turned on. Gforth provides several levels of assertions for |
this purpose: |
this purpose: |
|
|
doc-assert0( |
doc-assert0( |
Line 1609 probably more appropriate than an assert
|
Line 1629 probably more appropriate than an assert
|
@section Threading Words |
@section Threading Words |
|
|
These words provide access to code addresses and other threading stuff |
These words provide access to code addresses and other threading stuff |
in gforth (and, possibly, other interpretive Forths). It more or less |
in Gforth (and, possibly, other interpretive Forths). It more or less |
abstracts away the differences between direct and indirect threading |
abstracts away the differences between direct and indirect threading |
(and, for direct threading, the machine dependences). However, at |
(and, for direct threading, the machine dependences). However, at |
present this wordset is still inclomplete. It is also pretty low-level; |
present this wordset is still inclomplete. It is also pretty low-level; |
Line 1628 doc-/does-handler
|
Line 1648 doc-/does-handler
|
@node ANS conformance, Model, Words, Top |
@node ANS conformance, Model, Words, Top |
@chapter ANS conformance |
@chapter ANS conformance |
|
|
ANS Forth systems are required to document certain implementation |
To the best of our knowledge, Gforth is an |
choices. This chapter tries to meet these requirements. In many cases it |
|
gives a way to ask the system for the information instead of providing |
ANS Forth System |
the information directly, in particular, if the information depends on |
@itemize |
the processor, the operating system or the installation options chosen, |
@item providing the Core Extensions word set |
or if they are likely to change during the maintenance of gforth. |
@item providing the Block word set |
|
@item providing the Block Extensions word set |
|
@item providing the Double-Number word set |
|
@item providing the Double-Number Extensions word set |
|
@item providing the Exception word set |
|
@item providing the Exception Extensions word set |
|
@item providing the Facility word set |
|
@item providing @code{MS} and @code{TIME&DATE} from the Facility Extensions word set |
|
@item providing the File Access word set |
|
@item providing the File Access Extensions word set |
|
@item providing the Floating-Point word set |
|
@item providing the Floating-Point Extensions word set |
|
@item providing the Locals word set |
|
@item providing the Locals Extensions word set |
|
@item providing the Memory-Allocation word set |
|
@item providing the Memory-Allocation Extensions word set (that one's easy) |
|
@item providing the Programming-Tools word set |
|
@item providing @code{AHEAD}, @code{BYE}, @code{CS-PICK}, @code{CS-ROLL}, @code{STATE}, @code{[ELSE]}, @code{[IF]}, @code{[THEN]} from the Programming-Tools Extensions word set |
|
@item providing the Search-Order word set |
|
@item providing the Search-Order Extensions word set |
|
@item providing the String word set |
|
@item providing the String Extensions word set (another easy one) |
|
@end itemize |
|
|
|
In addition, ANS Forth systems are required to document certain |
|
implementation choices. This chapter tries to meet these |
|
requirements. In many cases it gives a way to ask the system for the |
|
information instead of providing the information directly, in |
|
particular, if the information depends on the processor, the operating |
|
system or the installation options chosen, or if they are likely to |
|
change during the maintenance of Gforth. |
|
|
@comment The framework for the rest has been taken from pfe. |
@comment The framework for the rest has been taken from pfe. |
|
|
Line 1649 or if they are likely to change during t
|
Line 1699 or if they are likely to change during t
|
* The optional Memory-Allocation word set:: |
* The optional Memory-Allocation word set:: |
* The optional Programming-Tools word set:: |
* The optional Programming-Tools word set:: |
* The optional Search-Order word set:: |
* The optional Search-Order word set:: |
* The optional String word set:: |
|
@end menu |
@end menu |
|
|
|
|
Line 1660 or if they are likely to change during t
|
Line 1709 or if they are likely to change during t
|
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* core-idef:: |
* core-idef:: Implementation Defined Options |
* core-ambcond:: |
* core-ambcond:: Ambiguous Conditions |
* core-other:: |
* core-other:: Other System Documentation |
@end menu |
@end menu |
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node core-idef, core-ambcond, The Core Words, The Core Words |
@node core-idef, core-ambcond, The Core Words, The Core Words |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item (Cell) aligned addresses: |
@item (Cell) aligned addresses: |
processor-dependent. Gforths alignment words perform natural alignment |
processor-dependent. Gforth's alignment words perform natural alignment |
(e.g., an address aligned for a datum of size 8 is divisible by |
(e.g., an address aligned for a datum of size 8 is divisible by |
8). Unaligned accesses usually result in a @code{-23 THROW}. |
8). Unaligned accesses usually result in a @code{-23 THROW}. |
|
|
Line 1699 installation-dependent. Currently a char
|
Line 1747 installation-dependent. Currently a char
|
(Comments on that requested). |
(Comments on that requested). |
|
|
@item character-set extensions and matching of names: |
@item character-set extensions and matching of names: |
Any character except 0 can be used in a name. Matching is |
Any character except the ASCII NUL charcter can be used in a |
case-insensitive. The matching is performed using the C function |
name. Matching is case-insensitive. The matching is performed using the |
@code{strncasecmp}, whose function is probably influenced by the |
C function @code{strncasecmp}, whose function is probably influenced by |
locale. E.g., the @code{C} locale does not know about accents and |
the locale. E.g., the @code{C} locale does not know about accents and |
umlauts, so they are matched case-sensitively in that locale. For |
umlauts, so they are matched case-sensitively in that locale. For |
portability reasons it is best to write programs such that they work in |
portability reasons it is best to write programs such that they work in |
the @code{C} locale. Then one can use libraries written by a Polish |
the @code{C} locale. Then one can use libraries written by a Polish |
Line 1762 Given by the constant @code{/line}. Curr
|
Line 1810 Given by the constant @code{/line}. Curr
|
31 |
31 |
|
|
@item method of selecting the user input device: |
@item method of selecting the user input device: |
The user input device is the standard input. There is current no way to |
The user input device is the standard input. There is currently no way to |
change it from within gforth. However, the input can typically be |
change it from within Gforth. However, the input can typically be |
redirected in the command line that starts gforth. |
redirected in the command line that starts Gforth. |
|
|
@item method of selecting the user output device: |
@item method of selecting the user output device: |
The user output device is the standard output. It cannot be redirected |
The user output device is the standard output. It cannot be redirected |
from within gforth, but typically from the command line that starts |
from within Gforth, but typically from the command line that starts |
gforth. Gforth uses buffered output, so output on a terminal does not |
Gforth. Gforth uses buffered output, so output on a terminal does not |
become visible before the next newline or buffer overflow. Output on |
become visible before the next newline or buffer overflow. Output on |
non-terminals is invisible until the buffer overflows. |
non-terminals is invisible until the buffer overflows. |
|
|
@item methods of dictionary compilation: |
@item methods of dictionary compilation: |
Waht are we expected to document here? |
What are we expected to document here? |
|
|
@item number of bits in one address unit: |
@item number of bits in one address unit: |
@code{s" address-units-bits" environment? drop .}. 8 in all current |
@code{s" address-units-bits" environment? drop .}. 8 in all current |
Line 1810 string.
|
Line 1858 string.
|
Varies. You can determine the size at a specific time using @code{lp@ |
Varies. You can determine the size at a specific time using @code{lp@ |
tib - .}. It is shared with the locals stack and TIBs of files that |
tib - .}. It is shared with the locals stack and TIBs of files that |
include the current file. You can change the amount of space for TIBs |
include the current file. You can change the amount of space for TIBs |
and locals stack at gforth startup with the command line option |
and locals stack at Gforth startup with the command line option |
@code{-l}. |
@code{-l}. |
|
|
@item size of the pictured numeric output buffer: |
@item size of the pictured numeric output buffer: |
Line 1854 No.
|
Line 1902 No.
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node core-ambcond, core-other, core-idef, The Core Words |
@node core-ambcond, core-other, core-idef, The Core Words |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 1976 stack items are loop control parameters
|
Line 2023 stack items are loop control parameters
|
@item name not defined by @code{VALUE} used by @code{TO}: |
@item name not defined by @code{VALUE} used by @code{TO}: |
@code{-32 throw} (Invalid name argument) |
@code{-32 throw} (Invalid name argument) |
|
|
@item name not found (@code{'}, @code{POSTPONE}, @code{[']}, @code{[COMPILE]}: |
@item name not found (@code{'}, @code{POSTPONE}, @code{[']}, @code{[COMPILE]}): |
@code{-13 throw} (Undefined word) |
@code{-13 throw} (Undefined word) |
|
|
@item parameters are not of the same type (@code{DO}, @code{?DO}, @code{WITHIN}): |
@item parameters are not of the same type (@code{DO}, @code{?DO}, @code{WITHIN}): |
Line 1991 Assume @code{: X POSTPONE TO ; IMMEDIATE
|
Line 2038 Assume @code{: X POSTPONE TO ; IMMEDIATE
|
Not checked. The string will be ok, but the count will, of course, |
Not checked. The string will be ok, but the count will, of course, |
contain only the least significant bits of the length. |
contain only the least significant bits of the length. |
|
|
@item u greater than or equal to the number of bits in a cell (@code{LSHIFT}, @code{RSHIFT}: |
@item u greater than or equal to the number of bits in a cell (@code{LSHIFT}, @code{RSHIFT}): |
Processor-dependent. Typical behaviours are returning 0 and using only |
Processor-dependent. Typical behaviours are returning 0 and using only |
the low bits of the shift count. |
the low bits of the shift count. |
|
|
Line 2010 Not checked. As usual, you can expect me
|
Line 2057 Not checked. As usual, you can expect me
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node core-other, , core-ambcond, The Core Words |
@node core-other, , core-ambcond, The Core Words |
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
@subsection Other system documentation |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2041 writing, this gives 70108 (bytes) on a 3
|
Line 2087 writing, this gives 70108 (bytes) on a 3
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Block word set, The optional Double Number word set, The Core Words, ANS conformance |
@node The optional Block word set, The optional Double Number word set, The Core Words, ANS conformance |
@comment node-name, next, previous, up |
|
@section The optional Block word set |
@section The optional Block word set |
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* block-idef:: |
* block-idef:: Implementation Defined Options |
* block-ambcond:: |
* block-ambcond:: Ambiguous Conditions |
* block-other:: |
* block-other:: Other System Documentation |
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node block-idef, block-ambcond, The optional Block word set, The optional Block word set |
@node block-idef, block-ambcond, The optional Block word set, The optional Block word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2071 each line preceded by the line number.
|
Line 2115 each line preceded by the line number.
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node block-ambcond, block-other, block-idef, The optional Block word set |
@node block-ambcond, block-other, block-idef, The optional Block word set |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2102 non-block input, the system will get qui
|
Line 2145 non-block input, the system will get qui
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node block-other, , block-ambcond, The optional Block word set |
@node block-other, , block-ambcond, The optional Block word set |
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
@subsection Other system documentation |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2119 depends on your disk space.
|
Line 2161 depends on your disk space.
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Double Number word set, The optional Exception word set, The optional Block word set, ANS conformance |
@node The optional Double Number word set, The optional Exception word set, The optional Block word set, ANS conformance |
@comment node-name, next, previous, up |
|
@section The optional Double Number word set |
@section The optional Double Number word set |
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* double-idef:: |
* double-ambcond:: Ambiguous Conditions |
* double-ambcond:: |
|
* double-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node double-idef, double-ambcond, The optional Double Number word set, The optional Double Number word set |
@node double-ambcond, , The optional Double Number word set, The optional Double Number word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
|
@c --------------------------------------------------------------------- |
|
|
|
No additional documentation requirements. |
|
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node double-ambcond, double-other, double-idef, The optional Double Number word set |
|
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item @var{d} outside of range on @var{n} in @code{D>S}: |
@item @var{d} outside of range of @var{n} in @code{D>S}: |
The least significant cell of @var{d} is produced. |
The least significant cell of @var{d} is produced. |
|
|
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node double-other, , double-ambcond, The optional Double Number word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
No additional documentation requirements. |
|
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Exception word set, The optional Facility word set, The optional Double Number word set, ANS conformance |
@node The optional Exception word set, The optional Facility word set, The optional Double Number word set, ANS conformance |
@comment node-name, next, previous, up |
|
@section The optional Exception word set |
@section The optional Exception word set |
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* exception-idef:: |
* exception-idef:: Implementation Defined Options |
* exception-ambcond:: |
|
* exception-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node exception-idef, exception-ambcond, The optional Exception word set, The optional Exception word set |
@node exception-idef, , The optional Exception word set, The optional Exception word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2192 strange number; e.g., @code{-1000 THROW}
|
Line 2208 strange number; e.g., @code{-1000 THROW}
|
488} on my system. |
488} on my system. |
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node exception-ambcond, exception-other, exception-idef, The optional Exception word set |
|
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
|
@c --------------------------------------------------------------------- |
|
|
|
No additional documentation requirements. |
|
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node exception-other, , exception-ambcond, The optional Exception word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
No additional documentation requirements. |
|
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Facility word set, The optional File-Access word set, The optional Exception word set, ANS conformance |
@node The optional Facility word set, The optional File-Access word set, The optional Exception word set, ANS conformance |
@comment node-name, next, previous, up |
|
@section The optional Facility word set |
@section The optional Facility word set |
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* facility-idef:: |
* facility-idef:: Implementation Defined Options |
* facility-ambcond:: |
* facility-ambcond:: Ambiguous Conditions |
* facility-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node facility-idef, facility-ambcond, The optional Facility word set, The optional Facility word set |
@node facility-idef, facility-ambcond, The optional Facility word set, The optional Facility word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2242 another question.
|
Line 2236 another question.
|
|
|
@item repeatability to be expected from the execution of @code{MS}: |
@item repeatability to be expected from the execution of @code{MS}: |
System dependent. On Unix, a lot depends on load. If the system is |
System dependent. On Unix, a lot depends on load. If the system is |
lightly loaded, and the delay is short enough that gforth does not get |
lightly loaded, and the delay is short enough that Gforth does not get |
swapped out, the performance should be acceptable. Under MS-DOS and |
swapped out, the performance should be acceptable. Under MS-DOS and |
other single-tasking systems, it should be good. |
other single-tasking systems, it should be good. |
|
|
Line 2250 other single-tasking systems, it should
|
Line 2244 other single-tasking systems, it should
|
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node facility-ambcond, facility-other, facility-idef, The optional Facility word set |
@node facility-ambcond, , facility-idef, The optional Facility word set |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2265 simply nothing happen.
|
Line 2258 simply nothing happen.
|
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node facility-other, , facility-ambcond, The optional Facility word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
No additional documentation requirements. |
|
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional File-Access word set, The optional Floating-Point word set, The optional Facility word set, ANS conformance |
@node The optional File-Access word set, The optional Floating-Point word set, The optional Facility word set, ANS conformance |
@comment node-name, next, previous, up |
|
@section The optional File-Access word set |
@section The optional File-Access word set |
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* file-idef:: |
* file-idef:: Implementation Defined Options |
* file-ambcond:: |
* file-ambcond:: Ambiguous Conditions |
* file-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node file-idef, file-ambcond, The optional File-Access word set, The optional File-Access word set |
@node file-idef, file-ambcond, The optional File-Access word set, The optional File-Access word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2299 No additional documentation requirements
|
Line 2280 No additional documentation requirements
|
@code{R/O}, @code{R/W} and @code{BIN} work as you would |
@code{R/O}, @code{R/W} and @code{BIN} work as you would |
expect. @code{W/O} translates into the C file opening mode @code{w} (or |
expect. @code{W/O} translates into the C file opening mode @code{w} (or |
@code{wb}): The file is cleared, if it exists, and created, if it does |
@code{wb}): The file is cleared, if it exists, and created, if it does |
not (both with @code{open-file} and @code{create-file}. Under Unix |
not (both with @code{open-file} and @code{create-file}). Under Unix |
@code{create-file} creates a file with 666 permissions modified by your |
@code{create-file} creates a file with 666 permissions modified by your |
umask. |
umask. |
|
|
Line 2325 along with the retured mode.
|
Line 2306 along with the retured mode.
|
All files that are left via the exception are closed. |
All files that are left via the exception are closed. |
|
|
@item @var{ior} values and meaning: |
@item @var{ior} values and meaning: |
The @var{ior}s returned by the file words are intended as throw |
The @var{ior}s returned by the file and memory allocation words are |
codes. They typically are in the range -512@minus{}-2047 of OS errors. |
intended as throw codes. They typically are in the range |
The mapping from OS error numbers to @var{ior}s is |
-512@minus{}-2047 of OS errors. The mapping from OS error numbers to |
-512@minus{}@var{errno}. |
@var{ior}s is -512@minus{}@var{errno}. |
|
|
@item maximum depth of file input nesting: |
@item maximum depth of file input nesting: |
limited by the amount of return stack, locals/TIB stack, and the number |
limited by the amount of return stack, locals/TIB stack, and the number |
Line 2351 methods could be implemented if there is
|
Line 2332 methods could be implemented if there is
|
@end table |
@end table |
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node file-ambcond, file-other, file-idef, The optional File-Access word set |
@node file-ambcond, , file-idef, The optional File-Access word set |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
Line 2388 the source which loaded the block. (Bett
|
Line 2368 the source which loaded the block. (Bett
|
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node file-other, , file-ambcond, The optional File-Access word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
|
|
|
@item |
|
|
|
@end table |
|
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Floating-Point word set, The optional Locals word set, The optional File-Access word set, ANS conformance |
@node The optional Floating-Point word set, The optional Locals word set, The optional File-Access word set, ANS conformance |
@comment node-name, next, previous, up |
@section The optional Floating-Point word set |
@section |
|
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* floating-idef:: floating-ambcond:: floating-other:: |
* floating-idef:: Implementation Defined Options |
* floating-ambcond:: |
* floating-ambcond:: Ambiguous Conditions |
* floating-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node floating-idef, floating-ambcond, The optional Floating-Point word set, The optional Floating-Point word set |
@node floating-idef, floating-ambcond, The optional Floating-Point word set, The optional Floating-Point word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item format and range of floating point numbers: |
|
System-dependent; the @code{double} type of C. |
@end table |
|
|
|
|
@item results of @code{REPRESENT} when @var{float} is out of range: |
|
System dependent; @code{REPRESENT} is implemented using the C library |
|
function @code{ecvt()} and inherits its behaviour in this respect. |
|
|
@c --------------------------------------------------------------------- |
@item rounding or truncation of floating-point numbers: |
@node floating-ambcond, floating-other, floating-idef, The optional Floating-Point word set |
What's the question?!! |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
@item size of floating-point stack: |
|
@code{s" FLOATING-STACK" environment? drop .}. Can be changed at startup |
|
with the command-line option @code{-f}. |
|
|
@item |
@item width of floating-point stack: |
|
@code{1 floats}. |
|
|
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node floating-other, , floating-ambcond, The optional Floating-Point word set |
@node floating-ambcond, , floating-idef, The optional Floating-Point word set |
@comment node-name, next, previous, up |
@subsection Ambiguous conditions |
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item @code{df@@} or @code{df!} used with an address that is not double-float aligned: |
|
System-dependent. Typically results in an alignment fault like other |
@end table |
alignment violations. |
|
|
|
@item @code{f@@} or @code{f!} used with an address that is not float aligned: |
|
System-dependent. Typically results in an alignment fault like other |
|
alignment violations. |
|
|
|
@item Floating-point result out of range: |
|
System-dependent. Can result in a @code{-55 THROW} (Floating-point |
|
unidentified fault), or can produce a special value representing, e.g., |
|
Infinity. |
|
|
|
@item @code{sf@@} or @code{sf!} used with an address that is not single-float aligned: |
|
System-dependent. Typically results in an alignment fault like other |
|
alignment violations. |
|
|
|
@item BASE is not decimal (@code{REPRESENT}, @code{F.}, @code{FE.}, @code{FS.}): |
|
The floating-point number is converted into decimal nonetheless. |
|
|
|
@item Both arguments are equal to zero (@code{FATAN2}): |
|
System-dependent. @code{FATAN2} is implemented using the C library |
|
function @code{atan2()}. |
|
|
|
@item Using ftan on an argument @var{r1} where cos(@var{r1}) is zero: |
|
System-dependent. Anyway, typically the cos of @var{r1} will not be zero |
|
because of small errors and the tan will be a very large (or very small) |
|
but finite number. |
|
|
@c ===================================================================== |
@item @var{d} cannot be presented precisely as a float in @code{D>F}: |
@node The optional Locals word set, The optional Memory-Allocation word set, The optional Floating-Point word set, ANS conformance |
The result is rounded to the nearest float. |
@comment node-name, next, previous, up |
|
@section |
|
@c ===================================================================== |
|
|
|
@menu |
@item dividing by zero: |
* locals-idef:: |
@code{-55 throw} (Floating-point unidentified fault) |
* locals-ambcond:: |
|
* locals-other:: |
|
@end menu |
|
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node locals-idef, locals-ambcond, The optional Locals word set, The optional Locals word set |
|
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
@item exponent too big for conversion (@code{DF!}, @code{DF@@}, @code{SF!}, @code{SF@@}): |
|
System dependent. On IEEE-FP based systems the number is converted into |
|
an infinity. |
|
|
@item |
@item @var{float}<1 (@code{facosh}): |
|
@code{-55 throw} (Floating-point unidentified fault) |
|
|
@end table |
@item @var{float}=<-1 (@code{flnp1}): |
|
@code{-55 throw} (Floating-point unidentified fault). On IEEE-FP systems |
|
negative infinity is typically produced for @var{float}=-1. |
|
|
|
@item @var{float}=<0 (@code{fln}, @code{flog}): |
|
@code{-55 throw} (Floating-point unidentified fault). On IEEE-FP systems |
|
negative infinity is typically produced for @var{float}=0. |
|
|
@c --------------------------------------------------------------------- |
@item @var{float}<0 (@code{fasinh}, @code{fsqrt}): |
@node locals-ambcond, locals-other, locals-idef, The optional Locals word set |
@code{-55 throw} (Floating-point unidentified fault). @code{fasinh} |
@comment node-name, next, previous, up |
produces values for these inputs on my Linux box (Bug in the C library?) |
@subsection Ambiguous conditions |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
@item |@var{float}|>1 (@code{facos}, @code{fasin}, @code{fatanh}): |
|
@code{-55 throw} (Floating-point unidentified fault). |
|
|
@item |
@item integer part of float cannot be represented by @var{d} in @code{f>d}: |
|
@code{-55 throw} (Floating-point unidentified fault). |
|
|
|
@item string larger than pictured numeric output area (@code{f.}, @code{fe.}, @code{fs.}): |
|
This does not happen. |
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node locals-other, , locals-ambcond, The optional Locals word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
|
|
|
@item |
|
|
|
@end table |
|
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Memory-Allocation word set, The optional Programming-Tools word set, The optional Locals word set, ANS conformance |
@node The optional Locals word set, The optional Memory-Allocation word set, The optional Floating-Point word set, ANS conformance |
@comment node-name, next, previous, up |
@section The optional Locals word set |
@section |
|
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* memory-idef:: |
* locals-idef:: Implementation Defined Options |
* memory-ambcond:: |
* locals-ambcond:: Ambiguous Conditions |
* memory-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node memory-idef, memory-ambcond, The optional Memory-Allocation word set, The optional Memory-Allocation word set |
@node locals-idef, locals-ambcond, The optional Locals word set, The optional Locals word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item maximum number of locals in a definition: |
|
@code{s" #locals" environment? drop .}. Currently 15. This is a lower |
|
bound, e.g., on a 32-bit machine there can be 41 locals of up to 8 |
|
characters. The number of locals in a definition is bounded by the size |
|
of locals-buffer, which contains the names of the locals. |
|
|
@end table |
@end table |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node memory-ambcond, memory-other, memory-idef, The optional Memory-Allocation word set |
@node locals-ambcond, , locals-idef, The optional Locals word set |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item executing a named local in interpretation state: |
|
@code{-14 throw} (Interpreting a compile-only word). |
@end table |
|
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node memory-other, , memory-ambcond, The optional Memory-Allocation word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
|
|
|
@item |
@item @var{name} not defined by @code{VALUE} or @code{(LOCAL)} (@code{TO}): |
|
@code{-32 throw} (Invalid name argument) |
|
|
@end table |
@end table |
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Programming-Tools word set, The optional Search-Order word set, The optional Memory-Allocation word set, ANS conformance |
@node The optional Memory-Allocation word set, The optional Programming-Tools word set, The optional Locals word set, ANS conformance |
@comment node-name, next, previous, up |
@section The optional Memory-Allocation word set |
@section |
|
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* programming-idef:: |
* memory-idef:: Implementation Defined Options |
* programming-ambcond:: |
|
* programming-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node programming-idef, programming-ambcond, The optional Programming-Tools word set, The optional Programming-Tools word set |
@node memory-idef, , The optional Memory-Allocation word set, The optional Memory-Allocation word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item values and meaning of @var{ior}: |
|
The @var{ior}s returned by the file and memory allocation words are |
@end table |
intended as throw codes. They typically are in the range |
|
-512@minus{}-2047 of OS errors. The mapping from OS error numbers to |
|
@var{ior}s is -512@minus{}@var{errno}. |
@c --------------------------------------------------------------------- |
|
@node programming-ambcond, programming-other, programming-idef, The optional Programming-Tools word set |
|
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
|
|
|
@item |
|
|
|
@end table |
|
|
|
|
|
@c --------------------------------------------------------------------- |
|
@node programming-other, , programming-ambcond, The optional Programming-Tools word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
|
|
|
@item |
|
|
|
@end table |
@end table |
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional Search-Order word set, The optional String word set, The optional Programming-Tools word set, ANS conformance |
@node The optional Programming-Tools word set, The optional Search-Order word set, The optional Memory-Allocation word set, ANS conformance |
@comment node-name, next, previous, up |
@section The optional Programming-Tools word set |
@section |
|
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* search-idef:: |
* programming-idef:: Implementation Defined Options |
* search-ambcond:: |
* programming-ambcond:: Ambiguous Conditions |
* search-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node search-idef, search-ambcond, The optional Search-Order word set, The optional Search-Order word set |
@node programming-idef, programming-ambcond, The optional Programming-Tools word set, The optional Programming-Tools word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item ending sequence for input following @code{;code} and @code{code}: |
|
Not implemented (yet). |
|
|
@end table |
@item manner of processing input following @code{;code} and @code{code}: |
|
Not implemented (yet). |
|
|
|
@item search order capability for @code{EDITOR} and @code{ASSEMBLER}: |
|
Not implemented (yet). If they were implemented, they would use the |
|
search order wordset. |
|
|
|
@item source and format of display by @code{SEE}: |
|
The source for @code{see} is the intermediate code used by the inner |
|
interpreter. The current @code{see} tries to output Forth source code |
|
as well as possible. |
|
|
|
@end table |
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node search-ambcond, search-other, search-idef, The optional Search-Order word set |
@node programming-ambcond, , programming-idef, The optional Programming-Tools word set |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item deleting the compilation wordlist (@code{FORGET}): |
|
Not implemented (yet). |
|
|
@end table |
@item fewer than @var{u}+1 items on the control flow stack (@code{CS-PICK}, @code{CS-ROLL}): |
|
This typically results in an @code{abort"} with a descriptive error |
|
message (may change into a @code{-22 throw} (Control structure mismatch) |
|
in the future). You may also get a memory access error. If you are |
|
unlucky, this ambiguous condition is not caught. |
|
|
|
@item @var{name} can't be found (@code{forget}): |
|
Not implemented (yet). |
|
|
@c --------------------------------------------------------------------- |
@item @var{name} not defined via @code{CREATE}: |
@node search-other, , search-ambcond, The optional Search-Order word set |
@code{;code} is not implemented (yet). If it were, it would behave like |
@comment node-name, next, previous, up |
@code{DOES>} in this respect, i.e., change the execution semantics of |
@subsection Other system documentation |
the last defined word no matter how it was defined. |
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
@item @code{POSTPONE} applied to @code{[IF]}: |
|
After defining @code{: X POSTPONE [IF] ; IMMEDIATE}. @code{X} is |
|
equivalent to @code{[IF]}. |
|
|
@item |
@item reaching the end of the input source before matching @code{[ELSE]} or @code{[THEN]}: |
|
Continue in the same state of conditional compilation in the next outer |
|
input source. Currently there is no warning to the user about this. |
|
|
|
@item removing a needed definition (@code{FORGET}): |
|
Not implemented (yet). |
|
|
@end table |
@end table |
|
|
|
|
@c ===================================================================== |
@c ===================================================================== |
@node The optional String word set, , The optional Search-Order word set, ANS conformance |
@node The optional Search-Order word set, , The optional Programming-Tools word set, ANS conformance |
@comment node-name, next, previous, up |
@section The optional Search-Order word set |
@section |
|
@c ===================================================================== |
@c ===================================================================== |
|
|
@menu |
@menu |
* string-idef:: |
* search-idef:: Implementation Defined Options |
* string-ambcond:: |
* search-ambcond:: Ambiguous Conditions |
* string-other:: |
|
@end menu |
@end menu |
|
|
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node string-idef, string-ambcond, The optional String word set, The optional String word set |
@node search-idef, search-ambcond, The optional Search-Order word set, The optional Search-Order word set |
@comment node-name, next, previous, up |
|
@subsection Implementation Defined Options |
@subsection Implementation Defined Options |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item maximum number of word lists in search order: |
|
@code{s" wordlists" environment? drop .}. Currently 16. |
|
|
@end table |
@item minimum search order: |
|
@code{root root}. |
|
|
|
@end table |
|
|
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
@node string-ambcond, string-other, string-idef, The optional String word set |
@node search-ambcond, , search-idef, The optional Search-Order word set |
@comment node-name, next, previous, up |
|
@subsection Ambiguous conditions |
@subsection Ambiguous conditions |
@c --------------------------------------------------------------------- |
@c --------------------------------------------------------------------- |
|
|
@table @i |
@table @i |
|
|
@item |
@item changing the compilation wordlist (during compilation): |
|
The definition is put into the wordlist that is the compilation wordlist |
|
when @code{REVEAL} is executed (by @code{;}, @code{DOES>}, |
|
@code{RECURSIVE}, etc.). |
|
|
@end table |
@item search order empty (@code{previous}): |
|
@code{abort" Vocstack empty"}. |
|
|
@c --------------------------------------------------------------------- |
|
@node string-other, , string-ambcond, The optional String word set |
|
@comment node-name, next, previous, up |
|
@subsection Other system documentation |
|
@c --------------------------------------------------------------------- |
|
|
|
@table @i |
@item too many word lists in search order (@code{also}): |
|
@code{abort" Vocstack full"}. |
@item |
|
|
|
@end table |
@end table |
|
|
|
|
|
@node Model, Emacs and Gforth, ANS conformance, Top |
@node Model, Emacs and GForth, ANS conformance, Top |
|
@chapter Model |
@chapter Model |
|
|
@node Emacs and GForth, Internals, Model, Top |
@node Emacs and Gforth, Internals, Model, Top |
@chapter Emacs and GForth |
@chapter Emacs and Gforth |
|
|
GForth comes with @file{gforth.el}, an improved version of |
Gforth comes with @file{gforth.el}, an improved version of |
@file{forth.el} by Goran Rydqvist (icluded in the TILE package). The |
@file{forth.el} by Goran Rydqvist (icluded in the TILE package). The |
improvements are a better (but still not perfect) handling of |
improvements are a better (but still not perfect) handling of |
indentation. I have also added comment paragraph filling (@kbd{M-q}), |
indentation. I have also added comment paragraph filling (@kbd{M-q}), |
Line 2730 stuff I do not use alone, even though so
|
Line 2683 stuff I do not use alone, even though so
|
TILE. To get a description of these features, enter Forth mode and type |
TILE. To get a description of these features, enter Forth mode and type |
@kbd{C-h m}. |
@kbd{C-h m}. |
|
|
In addition, GForth supports Emacs quite well: The source code locations |
In addition, Gforth supports Emacs quite well: The source code locations |
given in error messages, debugging output (from @code{~~}) and failed |
given in error messages, debugging output (from @code{~~}) and failed |
assertion messages are in the right format for Emacs' compilation mode |
assertion messages are in the right format for Emacs' compilation mode |
(@pxref{Compilation, , Running Compilations under Emacs, emacs, Emacs |
(@pxref{Compilation, , Running Compilations under Emacs, emacs, Emacs |
Line 2742 Also, if you @code{include} @file{etags.
|
Line 2695 Also, if you @code{include} @file{etags.
|
(@pxref{Tags, , Tags Tables, emacs, Emacs Manual}) will be produced that |
(@pxref{Tags, , Tags Tables, emacs, Emacs Manual}) will be produced that |
contains the definitions of all words defined afterwards. You can then |
contains the definitions of all words defined afterwards. You can then |
find the source for a word using @kbd{M-.}. Note that emacs can use |
find the source for a word using @kbd{M-.}. Note that emacs can use |
several tags files at the same time (e.g., one for the gforth sources |
several tags files at the same time (e.g., one for the Gforth sources |
and one for your program). |
and one for your program). |
|
|
To get all these benefits, add the following lines to your @file{.emacs} |
To get all these benefits, add the following lines to your @file{.emacs} |
Line 2753 file:
|
Line 2706 file:
|
(setq auto-mode-alist (cons '("\\.fs\\'" . forth-mode) auto-mode-alist)) |
(setq auto-mode-alist (cons '("\\.fs\\'" . forth-mode) auto-mode-alist)) |
@end example |
@end example |
|
|
@node Internals, Bugs, Emacs and GForth, Top |
@node Internals, Bugs, Emacs and Gforth, Top |
@chapter Internals |
@chapter Internals |
|
|
Reading this section is not necessary for programming with gforth. It |
Reading this section is not necessary for programming with Gforth. It |
should be helpful for finding your way in the gforth sources. |
should be helpful for finding your way in the Gforth sources. |
|
|
@menu |
@menu |
* Portability:: |
* Portability:: |
* Threading:: |
* Threading:: |
* Primitives:: |
* Primitives:: |
* System Architecture:: |
* System Architecture:: |
|
* Performance:: |
@end menu |
@end menu |
|
|
@node Portability, Threading, Internals, Internals |
@node Portability, Threading, Internals, Internals |
Line 2795 Double-Word Integers, gcc.info, GNU C Ma
|
Line 2749 Double-Word Integers, gcc.info, GNU C Ma
|
double numbers. GNU C is available for free on all important (and many |
double numbers. GNU C is available for free on all important (and many |
unimportant) UNIX machines, VMS, 80386s running MS-DOS, the Amiga, and |
unimportant) UNIX machines, VMS, 80386s running MS-DOS, the Amiga, and |
the Atari ST, so a Forth written in GNU C can run on all these |
the Atari ST, so a Forth written in GNU C can run on all these |
machines@footnote{Due to Apple's look-and-feel lawsuit it is not |
machines. |
available on the Mac (@pxref{Boycott, , Protect Your Freedom---Fight |
|
``Look And Feel'', gcc.info, GNU C Manual}).}. |
|
|
|
Writing in a portable language has the reputation of producing code that |
Writing in a portable language has the reputation of producing code that |
is slower than assembly. For our Forth engine we repeatedly looked at |
is slower than assembly. For our Forth engine we repeatedly looked at |
Line 3088 To see what assembly code is produced fo
|
Line 3040 To see what assembly code is produced fo
|
with your compiler and your flag settings, type @code{make engine.s} and |
with your compiler and your flag settings, type @code{make engine.s} and |
look at the resulting file @file{engine.s}. |
look at the resulting file @file{engine.s}. |
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@node System Architecture, , Primitives, Internals |
@node System Architecture, Performance, Primitives, Internals |
@section System Architecture |
@section System Architecture |
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|
Our Forth system consists not only of primitives, but also of |
Our Forth system consists not only of primitives, but also of |
Line 3111 possible, because we do not want to dist
|
Line 3063 possible, because we do not want to dist
|
same image file, and to make it easy for the users to use their image |
same image file, and to make it easy for the users to use their image |
files on many machines. We currently need to create a different image |
files on many machines. We currently need to create a different image |
file for machines with different cell sizes and different byte order |
file for machines with different cell sizes and different byte order |
(little- or big-endian)@footnote{We consider adding information to the |
(little- or big-endian)@footnote{We are considering adding information to the |
image file that enables the loader to change the byte order.}. |
image file that enables the loader to change the byte order.}. |
|
|
Forth code that is going to end up in a portable image file has to |
Forth code that is going to end up in a portable image file has to |
Line 3131 at run-time. The loader also has to repl
|
Line 3083 at run-time. The loader also has to repl
|
primitive calls with the appropriate code-field addresses (or code |
primitive calls with the appropriate code-field addresses (or code |
addresses in the case of direct threading). |
addresses in the case of direct threading). |
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|
@node Performance, , System Architecture, Internals |
|
@section Performance |
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|
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On RISCs the Gforth engine is very close to optimal; i.e., it is usually |
|
impossible to write a significantly faster engine. |
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|
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On register-starved machines like the 386 architecture processors |
|
improvements are possible, because @code{gcc} does not utilize the |
|
registers as well as a human, even with explicit register declarations; |
|
e.g., Bernd Beuster wrote a Forth system fragment in assembly language |
|
and hand-tuned it for the 486; this system is 1.19 times faster on the |
|
Sieve benchmark on a 486DX2/66 than Gforth compiled with |
|
@code{gcc-2.6.3} with @code{-DFORCE_REG}. |
|
|
|
However, this potential advantage of assembly language implementations |
|
is not necessarily realized in complete Forth systems: We compared |
|
Gforth (compiled with @code{gcc-2.6.3} and @code{-DFORCE_REG}) with |
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Win32Forth and LMI's NT Forth, two systems written in assembly, and with |
|
two systems written in C: PFE-0.9.11 (compiled with @code{gcc-2.6.3} |
|
with the default configuration for Linux: @code{-O2 -fomit-frame-pointer |
|
-DUSE_REGS}) and ThisForth Beta (compiled with gcc-2.6.3 -O3 |
|
-fomit-frame-pointer). We benchmarked Gforth, PFE and ThisForth on a |
|
486DX2/66 under Linux. Kenneth O'Heskin kindly provided the results for |
|
Win32Forth and NT Forth on a 486DX2/66 with similar memory performance |
|
under Windows NT. |
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|
|
We used four small benchmarks: the ubiquitous Sieve; bubble-sorting and |
|
matrix multiplication come from the Stanford integer benchmarks and have |
|
been translated into Forth by Martin Fraeman; we used the versions |
|
included in the TILE Forth package; and a recursive Fibonacci number |
|
computation for benchmark calling performance. The following table shows |
|
the time taken for the benchmarks scaled by the time taken by Gforth (in |
|
other words, it shows the speedup factor that Gforth achieved over the |
|
other systems). |
|
|
|
@example |
|
relative Win32- NT This- |
|
time Gforth Forth Forth PFE Forth |
|
sieve 1.00 1.30 1.07 1.67 2.98 |
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bubble 1.00 1.30 1.40 1.66 |
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matmul 1.00 1.40 1.29 2.24 |
|
fib 1.00 1.44 1.26 1.82 2.82 |
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@end example |
|
|
|
You may find the good performance of Gforth compared with the systems |
|
written in assembly language quite surprising. One important reason for |
|
the disappointing performance of these systems is probably that they are |
|
not written optimally for the 486 (e.g., they use the @code{lods} |
|
instruction). In addition, Win32Forth uses a comfortable, but costly |
|
method for relocating the Forth image: like @code{cforth}, it computes |
|
the actual addresses at run time, resulting in two address computations |
|
per NEXT (@pxref{System Architecture}). |
|
|
|
The speedup of Gforth over PFE and ThisForth can be easily explained |
|
with the self-imposed restriction to standard C (although the measured |
|
implementation of PFE uses a GNU C extension: global register |
|
variables), which makes efficient threading impossible. Moreover, |
|
current C compilers have a hard time optimizing other aspects of the |
|
ThisForth source. |
|
|
|
Note that the performance of Gforth on 386 architecture processors |
|
varies widely with the version of @code{gcc} used. E.g., @code{gcc-2.5.8} |
|
failed to allocate any of the virtual machine registers into real |
|
machine registers by itself and would not work correctly with explicit |
|
register declarations, giving a 1.3 times slower engine (on a 486DX2/66 |
|
running the Sieve) than the one measured above. |
|
|
@node Bugs, Pedigree, Internals, Top |
@node Bugs, Pedigree, Internals, Top |
@chapter Bugs |
@chapter Bugs |
|
|
|
Known bugs are described in the file BUGS in the Gforth distribution. |
|
|
|
If you find a bug, please send a bug report to !!. A bug report should |
|
describe the Gforth version used (it is announced at the start of an |
|
interactive Gforth session), the machine and operating system (on Unix |
|
systems you can use @code{uname -a} to produce this information), the |
|
installation options (!! a way to find them out), and a complete list of |
|
changes you (or your installer) have made to the Gforth sources (if |
|
any); it should contain a program (or a sequence of keyboard commands) |
|
that reproduces the bug and a description of what you think constitutes |
|
the buggy behaviour. |
|
|
|
For a thorough guide on reporting bugs read @ref{Bug Reporting, , How |
|
to Report Bugs, gcc.info, GNU C Manual}. |
|
|
|
|
@node Pedigree, Word Index, Bugs, Top |
@node Pedigree, Word Index, Bugs, Top |
@chapter Pedigree |
@chapter Pedigree |
|
|
|
Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by |
|
Dirk Zoller) will cross-fertilize each other. Of course, a significant part of the design of Gforth was prescribed by ANS Forth. |
|
|
|
Bernd Paysan wrote BigForth, a child of VolksForth. |
|
|
|
VolksForth descends from F83. !! Authors? When? |
|
|
|
Laxen and Perry wrote F83 as a model implementation of the |
|
Forth-83 standard. !! Pedigree? When? |
|
|
|
A team led by Bill Ragsdale implemented fig-Forth on many processors in |
|
1979. Dean Sanderson and Bill Ragsdale developed the original |
|
implementation of fig-Forth based on microForth. |
|
|
|
!! microForth pedigree |
|
|
|
A part of the information in this section comes from @cite{The Evolution |
|
of Forth} by Elizabeth D. Rather, Donald R. Colburn and Charles |
|
H. Moore, presented at the HOPL-II conference and preprinted in SIGPLAN |
|
Notices 28(3), 1993. You can find more historical and genealogical |
|
information about Forth there. |
|
|
@node Word Index, Node Index, Pedigree, Top |
@node Word Index, Node Index, Pedigree, Top |
@chapter Word Index |
@chapter Word Index |
|
|
|
This index is as incomplete as the manual. |
|
|
|
@printindex fn |
|
|
@node Node Index, , Word Index, Top |
@node Node Index, , Word Index, Top |
@chapter Node Index |
@chapter Node Index |
|
|
|
This index is even less complete than the manual. |
|
|
@contents |
@contents |
@bye |
@bye |
|
|