version 1.34, 1996/08/21 14:58:40
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version 1.40, 1996/11/11 16:59:16
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Line 86 personal machines. This manual correspon
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Line 86 personal machines. This manual correspon
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* Other Books:: Things you might want to read |
* Other Books:: Things you might want to read |
* Invocation:: Starting Gforth |
* Invocation:: Starting Gforth |
* Words:: Forth words available in Gforth |
* Words:: Forth words available in Gforth |
|
* Tools:: Programming tools |
* ANS conformance:: Implementation-defined options etc. |
* ANS conformance:: Implementation-defined options etc. |
* Model:: The abstract machine of Gforth |
* Model:: The abstract machine of Gforth |
* Integrating Gforth:: Forth as scripting language for applications. |
* Integrating Gforth:: Forth as scripting language for applications. |
Line 600 Loads the Forth image @var{file} instead
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Line 601 Loads the Forth image @var{file} instead
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@item --path @var{path} |
@item --path @var{path} |
@item -p @var{path} |
@item -p @var{path} |
Uses @var{path} for searching the image file and Forth source code |
Uses @var{path} for searching the image file and Forth source code files |
files instead of the default in the environment variable |
instead of the default in the environment variable @code{GFORTHPATH} or |
@code{GFORTHPATH} or the path specified at installation time (typically |
the path specified at installation time (e.g., |
@file{/usr/local/lib/gforth:.}). A path is given as a @code{:}-separated |
@file{/usr/local/share/gforth/0.2.0:.}). A path is given as a list of |
list. |
directories, separated by @samp{:} (on Unix) or @samp{;} (on other OSs). |
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@item --dictionary-size @var{size} |
@item --dictionary-size @var{size} |
@item -m @var{size} |
@item -m @var{size} |
Line 662 the user initialization file @file{.gfor
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Line 663 the user initialization file @file{.gfor
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option @code{--no-rc} is given; this file is first searched in @file{.}, |
option @code{--no-rc} is given; this file is first searched in @file{.}, |
then in @file{~}, then in the normal path (see above). |
then in @file{~}, then in the normal path (see above). |
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@node Words, ANS conformance, Invocation, Top |
@node Words, Tools, Invocation, Top |
@chapter Forth Words |
@chapter Forth Words |
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@menu |
@menu |
Line 673 then in @file{~}, then in the normal pat
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Line 674 then in @file{~}, then in the normal pat
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* Control Structures:: |
* Control Structures:: |
* Locals:: |
* Locals:: |
* Defining Words:: |
* Defining Words:: |
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* Tokens for Words:: |
* Wordlists:: |
* Wordlists:: |
* Files:: |
* Files:: |
* Blocks:: |
* Blocks:: |
Line 755 double sized signed integer
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Line 757 double sized signed integer
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@item ud |
@item ud |
double sized unsigned integer |
double sized unsigned integer |
@item r |
@item r |
Float |
Float (on the FP stack) |
@item a_ |
@item a_ |
Cell-aligned address |
Cell-aligned address |
@item c_ |
@item c_ |
Char-aligned address (note that a Char is two bytes in Windows NT) |
Char-aligned address (note that a Char may have two bytes in Windows NT) |
@item f_ |
@item f_ |
Float-aligned address |
Float-aligned address |
@item df_ |
@item df_ |
Line 772 Execution token, same size as Cell
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Line 774 Execution token, same size as Cell
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Wordlist ID, same size as Cell |
Wordlist ID, same size as Cell |
@item f83name |
@item f83name |
Pointer to a name structure |
Pointer to a name structure |
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@item " |
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string in the input stream (not the stack). The terminating character is |
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a blank by default. If it is not a blank, it is shown in @code{<>} |
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quotes. |
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@end table |
@end table |
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@node Arithmetic, Stack Manipulation, Notation, Words |
@node Arithmetic, Stack Manipulation, Notation, Words |
Line 849 The format of floating point numbers rec
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Line 856 The format of floating point numbers rec
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interpreter is: a signed decimal number, possibly containing a decimal |
interpreter is: a signed decimal number, possibly containing a decimal |
point (@code{.}), followed by @code{E} or @code{e}, optionally followed |
point (@code{.}), followed by @code{E} or @code{e}, optionally followed |
by a signed integer (the exponent). E.g., @code{1e} ist the same as |
by a signed integer (the exponent). E.g., @code{1e} ist the same as |
@code{+1.0e+1}. Note that a number without @code{e} |
@code{+1.0e+0}. Note that a number without @code{e} |
is not interpreted as floating-point number, but as double (if the |
is not interpreted as floating-point number, but as double (if the |
number contains a @code{.}) or single precision integer. Also, |
number contains a @code{.}) or single precision integer. Also, |
conversions between string and floating point numbers always use base |
conversions between string and floating point numbers always use base |
Line 1734 E.g., a definition using @code{TO} might
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Line 1741 E.g., a definition using @code{TO} might
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: strcmp @{ addr1 u1 addr2 u2 -- n @} |
: strcmp @{ addr1 u1 addr2 u2 -- n @} |
u1 u2 min 0 |
u1 u2 min 0 |
?do |
?do |
addr1 c@ addr2 c@ - |
addr1 c@@ addr2 c@@ - |
?dup-if |
?dup-if |
unloop exit |
unloop exit |
then |
then |
Line 1757 are initialized with the right value for
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Line 1764 are initialized with the right value for
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addr1 addr2 |
addr1 addr2 |
u1 u2 min 0 |
u1 u2 min 0 |
?do @{ s1 s2 @} |
?do @{ s1 s2 @} |
s1 c@ s2 c@ - |
s1 c@@ s2 c@@ - |
?dup-if |
?dup-if |
unloop exit |
unloop exit |
then |
then |
Line 1931 stack easier.
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Line 1938 stack easier.
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The whole definition must be in one line. |
The whole definition must be in one line. |
@end itemize |
@end itemize |
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Locals defined in this way behave like @code{VALUE}s |
Locals defined in this way behave like @code{VALUE}s (@xref{Simple |
(@xref{Values}). I.e., they are initialized from the stack. Using their |
Defining Words}). 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 |
Line 1957 programs harder to read, and easier to m
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Line 1964 programs harder to read, and easier to m
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merit of this syntax is that it is easy to implement using the ANS Forth |
merit of this syntax is that it is easy to implement using the ANS Forth |
locals wordset. |
locals wordset. |
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@node Defining Words, Wordlists, Locals, Words |
@node Defining Words, Tokens for Words, Locals, Words |
@section Defining Words |
@section Defining Words |
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@menu |
@menu |
* Values:: |
* Simple Defining Words:: |
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* Colon Definitions:: |
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* User-defined Defining Words:: |
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* Supplying names:: |
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* Interpretation and Compilation Semantics:: |
@end menu |
@end menu |
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@node Values, , Defining Words, Defining Words |
@node Simple Defining Words, Colon Definitions, Defining Words, Defining Words |
@subsection Values |
@subsection Simple Defining Words |
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doc-constant |
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doc-2constant |
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doc-fconstant |
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doc-variable |
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doc-2variable |
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doc-fvariable |
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doc-create |
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doc-user |
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doc-value |
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doc-to |
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doc-defer |
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doc-is |
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@node Colon Definitions, User-defined Defining Words, Simple Defining Words, Defining Words |
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@subsection Colon Definitions |
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@example |
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: name ( ... -- ... ) |
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word1 word2 word3 ; |
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@end example |
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creates a word called @code{name}, that, upon execution, executes |
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@code{word1 word2 word3}. @code{name} is a @dfn{(colon) definition}. |
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The explanation above is somewhat superficial. @xref{Interpretation and |
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Compilation Semantics} for an in-depth discussion of some of the issues |
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involved. |
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doc-: |
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doc-; |
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@node User-defined Defining Words, Supplying names, Colon Definitions, Defining Words |
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@subsection User-defined Defining Words |
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You can create new defining words simply by wrapping defining-time code |
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around existing defining words and putting the sequence in a colon |
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definition. |
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If you want the words defined with your defining words to behave |
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differently from words defined with standard defining words, you can |
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write your defining word like this: |
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@example |
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: def-word ( "name" -- ) |
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Create @var{code1} |
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DOES> ( ... -- ... ) |
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@var{code2} ; |
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def-word name |
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@end example |
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Technically, this fragment defines a defining word @code{def-word}, and |
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a word @code{name}; when you execute @code{name}, the address of the |
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body of @code{name} is put on the data stack and @var{code2} is executed |
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(the address of the body of @code{name} is the address @code{HERE} |
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returns immediately after the @code{CREATE}). |
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In other words, if you make the following definitions: |
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@example |
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: def-word1 ( "name" -- ) |
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Create @var{code1} ; |
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: action1 ( ... -- ... ) |
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@var{code2} ; |
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def-word name1 |
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@end example |
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Using @code{name1 action1} is equivalent to using @code{name}. |
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E.g., you can implement @code{Constant} in this way: |
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@example |
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: constant ( w "name" -- ) |
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create , |
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DOES> ( -- w ) |
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@@ ; |
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@end example |
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When you create a constant with @code{5 constant five}, first a new word |
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@code{five} is created, then the value 5 is laid down in the body of |
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@code{five} with @code{,}. When @code{five} is invoked, the address of |
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the body is put on the stack, and @code{@@} retrieves the value 5. |
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In the example above the stack comment after the @code{DOES>} specifies |
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the stack effect of the defined words, not the stack effect of the |
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following code (the following code expects the address of the body on |
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the top of stack, which is not reflected in the stack comment). This is |
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the convention that I use and recommend (it clashes a bit with using |
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locals declarations for stack effect specification, though). |
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@subsubsection Applications of @code{CREATE..DOES>} |
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You may wonder how to use this feature. Here are some usage patterns: |
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When you see a sequence of code occurring several times, and you can |
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identify a meaning, you will factor it out as a colon definition. When |
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you see similar colon definitions, you can factor them using |
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@code{CREATE..DOES>}. E.g., an assembler usually defines several words |
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that look very similar: |
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@example |
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: ori, ( reg-taget reg-source n -- ) |
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0 asm-reg-reg-imm ; |
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: andi, ( reg-taget reg-source n -- ) |
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1 asm-reg-reg-imm ; |
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@end example |
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This could be factored with: |
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@example |
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: reg-reg-imm ( op-code -- ) |
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create , |
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DOES> ( reg-taget reg-source n -- ) |
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@@ asm-reg-reg-imm ; |
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0 reg-reg-imm ori, |
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1 reg-reg-imm andi, |
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@end example |
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Another view of @code{CREATE..DOES>} is to consider it as a crude way to |
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supply a part of the parameters for a word (known as @dfn{currying} in |
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the functional language community). E.g., @code{+} needs two |
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parameters. Creating versions of @code{+} with one parameter fixed can |
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be done like this: |
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@example |
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: curry+ ( n1 -- ) |
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create , |
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DOES> ( n2 -- n1+n2 ) |
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@@ + ; |
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3 curry+ 3+ |
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-2 curry+ 2- |
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@end example |
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@subsubsection The gory details of @code{CREATE..DOES>} |
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doc-does> |
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This means that you need not use @code{CREATE} and @code{DOES>} in the |
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same definition; E.g., you can put the @code{DOES>}-part in a separate |
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definition. This allows us to, e.g., select among different DOES>-parts: |
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@example |
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: does1 |
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DOES> ( ... -- ... ) |
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... ; |
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: does2 |
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DOES> ( ... -- ... ) |
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... ; |
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: def-word ( ... -- ... ) |
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create ... |
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IF |
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does1 |
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ELSE |
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does2 |
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ENDIF ; |
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@end example |
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In a standard program you can apply a @code{DOES>}-part only if the last |
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word was defined with @code{CREATE}. In Gforth, the @code{DOES>}-part |
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will override the behaviour of the last word defined in any case. In a |
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standard program, you can use @code{DOES>} only in a colon |
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definition. In Gforth, you can also use it in interpretation state, in a |
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kind of one-shot mode: |
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@example |
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CREATE name ( ... -- ... ) |
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@var{initialization} |
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DOES> |
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@var{code} ; |
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@end example |
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This is equivalwent to the standard |
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@example |
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:noname |
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DOES> |
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@var{code} ; |
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CREATE name EXECUTE ( ... -- ... ) |
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@var{initialization} |
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@end example |
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You can get the address of the body of a word with |
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doc->body |
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@node Supplying names, Interpretation and Compilation Semantics, User-defined Defining Words, Defining Words |
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@subsection Supplying names for the defined words |
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By default, defining words take the names for the defined words from the |
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input stream. Sometimes you want to supply the name from a string. You |
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can do this with |
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doc-nextname |
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E.g., |
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@example |
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s" foo" nextname create |
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@end example |
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is equivalent to |
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@example |
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create foo |
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@end example |
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Sometimes you want to define a word without a name. You can do this with |
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@node Wordlists, Files, Defining Words, Words |
doc-noname |
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To make any use of the newly defined word, you need its execution |
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token. You can get it with |
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doc-lastxt |
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E.g., you can initialize a deferred word with an anonymous colon |
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definition: |
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@example |
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Defer deferred |
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noname : ( ... -- ... ) |
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... ; |
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lastxt IS deferred |
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@end example |
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@code{lastxt} also works when the last word was not defined as |
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@code{noname}. |
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The standard has also recognized the need for anonymous words and |
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provides |
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doc-:noname |
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This leaves the execution token for the word on the stack after the |
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closing @code{;}. You can rewrite the last example with @code{:noname}: |
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@example |
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Defer deferred |
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:noname ( ... -- ... ) |
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... ; |
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IS deferred |
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@end example |
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@node Interpretation and Compilation Semantics, , Supplying names, Defining Words |
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@subsection Interpretation and Compilation Semantics |
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The @dfn{interpretation semantics} of a word are what the text |
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interpreter does when it encounters the word in interpret state. It also |
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appears in some other contexts, e.g., the execution token returned by |
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@code{' @var{word}} identifies the interpretation semantics of |
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@var{word} (in other words, @code{' @var{word} execute} is equivalent to |
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interpret-state text interpretation of @code{@var{word}}). |
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The @dfn{compilation semantics} of a word are what the text interpreter |
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does when it encounters the word in compile state. It also appears in |
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other contexts, e.g, @code{POSTPONE @var{word}} compiles@footnote{In |
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standard terminology, ``appends to the current definition''.} the |
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compilation semantics of @var{word}. |
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The standard also talks about @dfn{execution semantics}. They are used |
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only for defining the interpretation and compilation semantics of many |
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words. By default, the interpretation semantics of a word are to |
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@code{execute} its execution semantics, and the compilation semantics of |
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a word are to @code{compile,} its execution semantics.@footnote{In |
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standard terminology: The default interpretation semantics are its |
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execution semantics; the default compilation semantics are to append its |
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execution semantics to the execution semantics of the current |
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definition.} |
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You can change the compilation semantics into @code{execute}ing the |
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execution semantics with |
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doc-immediate |
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You can remove the interpretation semantics of a word with |
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doc-compile-only |
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doc-restrict |
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Note that ticking (@code{'}) compile-only words gives an error |
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(``Interpreting a compile-only word''). |
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Gforth also allows you to define words with arbitrary combinations of |
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interpretation and compilation semantics. |
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doc-interpret/compile: |
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This feature was introduced for implementing @code{TO} and @code{S"}. I |
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recommend that you do not define such words, as cute as they may be: |
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they make it hard to get at both parts of the word in some contexts. |
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E.g., assume you want to get an execution token for the compilation |
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part. Instead, define two words, one that embodies the interpretation |
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part, and one that embodies the compilation part. |
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There is, however, a potentially useful application of this feature: |
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Providing differing implementations for the default semantics. While |
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this introduces redundancy and is therefore usually a bad idea, a |
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performance improvement may be worth the trouble. E.g., consider the |
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word @code{foobar}: |
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@example |
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: foobar |
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foo bar ; |
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@end example |
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Let us assume that @code{foobar} is called so frequently that the |
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calling overhead would take a significant amount of the run-time. We can |
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optimize it with @code{interpret/compile:}: |
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@example |
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:noname |
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foo bar ; |
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:noname |
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POSTPONE foo POSTPONE bar ; |
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interpret/compile: foobar |
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@end example |
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This definition has the same interpretation semantics and essentially |
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the same compilation semantics as the simple definition of |
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@code{foobar}, but the implementation of the compilation semantics is |
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more efficient with respect to run-time. |
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Some people try to use state-smart words to emulate the feature provided |
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by @code{interpret/compile:} (words are state-smart if they check |
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@code{STATE} during execution). E.g., they would try to code |
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@code{foobar} like this: |
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@example |
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: foobar |
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STATE @@ |
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IF ( compilation state ) |
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POSTPONE foo POSTPONE bar |
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ELSE |
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foo bar |
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ENDIF ; immediate |
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@end example |
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While this works if @code{foobar} is processed only by the text |
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interpreter, it does not work in other contexts (like @code{'} or |
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@code{POSTPONE}). E.g., @code{' foobar} will produce an execution token |
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for a state-smart word, not for the interpretation semantics of the |
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original @code{foobar}; when you execute this execution token (directly |
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with @code{EXECUTE} or indirectly through @code{COMPILE,}) in compile |
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state, the result will not be what you expected (i.e., it will not |
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perform @code{foo bar}). State-smart words are a bad idea. Simply don't |
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write them! |
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It is also possible to write defining words that define words with |
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arbitrary combinations of interpretation and compilation semantics (or, |
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preferably, arbitrary combinations of implementations of the default |
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semantics). In general, this looks like: |
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@example |
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: def-word |
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create-interpret/compile |
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@var{code1} |
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interpretation> |
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@var{code2} |
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<interpretation |
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compilation> |
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@var{code3} |
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<compilation ; |
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@end example |
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For a @var{word} defined with @code{def-word}, the interpretation |
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semantics are to push the address of the body of @var{word} and perform |
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@var{code2}, and the compilation semantics are to push the address of |
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the body of @var{word} and perform @var{code3}. E.g., @code{constant} |
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can also be defined like this: |
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@example |
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: constant ( n "name" -- ) |
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create-interpret/compile |
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, |
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interpretation> ( -- n ) |
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@@ |
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<interpretation |
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compilation> ( compilation. -- ; run-time. -- n ) |
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@@ postpone literal |
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<compilation ; |
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@end example |
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doc-create-interpret/compile |
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doc-interpretation> |
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doc-<interpretation |
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doc-compilation> |
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doc-<compilation |
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Note that words defined with @code{interpret/compile:} and |
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@code{create-interpret/compile} have an extended header structure that |
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differs from other words; however, unless you try to access them with |
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plain address arithmetic, you should not notice this. Words for |
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accessing the header structure usually know how to deal with this; e.g., |
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@code{' word >body} also gives you the body of a word created with |
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@code{create-interpret/compile}. |
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@node Tokens for Words, Wordlists, Defining Words, Words |
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@section Tokens for Words |
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This chapter describes the creation and use of tokens that represent |
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words on the stack (and in data space). |
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Named words have interpretation and compilation semantics. Unnamed words |
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just have execution semantics. |
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An @dfn{execution token} represents the execution semantics of an |
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unnamed word. An execution token occupies one cell. As explained in |
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section @ref{Supplying names}, the execution token of the last words |
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defined can be produced with |
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short-lastxt |
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You can perform the semantics represented by an execution token with |
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doc-execute |
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You can compile the word with |
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doc-compile, |
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In Gforth, the abstract data type @emph{execution token} is implemented |
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as CFA (code field address). |
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The interpretation semantics of a named word are also represented by an |
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execution token. You can get it with |
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doc-['] |
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doc-' |
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For literals, you use @code{'} in interpreted code and @code{[']} in |
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compiled code. Gforth's @code{'} and @code{[']} behave somewhat unusual |
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by complaining about compile-only words. To get an execution token for a |
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compiling word @var{X}, use @code{COMP' @var{X} drop} or @code{[COMP'] |
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@var{X} drop}. |
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|
The compilation semantics are represented by a @dfn{compilation token} |
|
consisting of two cells: @var{w xt}. The top cell @var{xt} is an |
|
execution token. The compilation semantics represented by the |
|
compilation token can be performed with @code{execute}, which consumes |
|
the whole compilation token, with an additional stack effect determined |
|
by the represented compilation semantics. |
|
|
|
doc-[comp'] |
|
doc-comp' |
|
|
|
You can compile the compilation semantics with @code{postpone,}. I.e., |
|
@code{COMP' @var{word} POSTPONE,} is equivalent to @code{POSTPONE |
|
@var{word}}. |
|
|
|
doc-postpone, |
|
|
|
At present, the @var{w} part of a compilation token is an execution |
|
token, and the @var{xt} part represents either @code{execute} or |
|
@code{compile,}. However, don't rely on that kowledge, unless necessary; |
|
we may introduce unusual compilation tokens in the future (e.g., |
|
compilation tokens representing the compilation semantics of literals). |
|
|
|
Named words are also represented by the @dfn{name token}. The abstract |
|
data type @emph{name token} is implemented as NFA (name field address). |
|
|
|
doc-find-name |
|
doc-name>int |
|
doc-name?int |
|
doc-name>comp |
|
doc-name>string |
|
|
|
@node Wordlists, Files, Tokens for Words, Words |
@section Wordlists |
@section Wordlists |
|
|
@node Files, Blocks, Wordlists, Words |
@node Files, Blocks, Wordlists, Words |
Line 2084 probably more appropriate than an assert
|
Line 2553 probably more appropriate than an assert
|
Gforth provides some words for defining primitives (words written in |
Gforth provides some words for defining primitives (words written in |
machine code), and for defining the the machine-code equivalent of |
machine code), and for defining the the machine-code equivalent of |
@code{DOES>}-based defining words. However, the machine-independent |
@code{DOES>}-based defining words. However, the machine-independent |
nature of Gforth poses a few problems: First of all. Gforth runs on |
nature of Gforth poses a few problems: First of all, Gforth runs on |
several architectures, so it can provide no standard assembler. What's |
several architectures, so it can provide no standard assembler. What's |
worse is that the register allocation not only depends on the processor, |
worse is that the register allocation not only depends on the processor, |
but also on the @code{gcc} version and options used. |
but also on the @code{gcc} version and options used. |
Line 2141 and use that in your assembly code.
|
Line 2610 and use that in your assembly code.
|
|
|
Another option for implementing normal and defining words efficiently |
Another option for implementing normal and defining words efficiently |
is: adding the wanted functionality to the source of Gforth. For normal |
is: adding the wanted functionality to the source of Gforth. For normal |
words you just have to edit @file{primitives}, defining words (for fast |
words you just have to edit @file{primitives} (@pxref{Automatic |
defined words) may require changes in @file{engine.c}, |
Generation}), defining words (equivalent to @code{;CODE} words, for fast |
@file{kernal.fs}, @file{prims2x.fs}, and possibly @file{cross.fs}. |
defined words) may require changes in @file{engine.c}, @file{kernal.fs}, |
|
@file{prims2x.fs}, and possibly @file{cross.fs}. |
|
|
|
|
@node Threading Words, , Assembler and Code words, Words |
@node Threading Words, , Assembler and Code words, Words |
Line 2174 doc-douser:
|
Line 2644 doc-douser:
|
doc-dodefer: |
doc-dodefer: |
doc-dofield: |
doc-dofield: |
|
|
Currently there is no installation-independent way for recogizing words |
You can recognize words defined by a @code{CREATE}...@code{DOES>} word |
defined by a @code{CREATE}...@code{DOES>} word; however, once you know |
with @code{>DOES-CODE}. If the word was defined in that way, the value |
that a word is defined by a @code{CREATE}...@code{DOES>} word, you can |
returned is different from 0 and identifies the @code{DOES>} used by the |
use @code{>DOES-CODE}. |
defining word. |
|
|
|
@node Tools, ANS conformance, Words, Top |
|
@chapter Tools |
|
|
@node ANS conformance, Model, Words, Top |
@menu |
|
* ANS Report:: Report the words used, sorted by wordset |
|
@end menu |
|
|
|
See also @ref{Emacs and Gforth}. |
|
|
|
@node ANS Report, , Tools, Tools |
|
@section @file{ans-report.fs}: Report the words used, sorted by wordset |
|
|
|
If you want to label a Forth program as ANS Forth Program, you must |
|
document which wordsets the program uses; for extension wordsets, it is |
|
helpful to list the words the program requires from these wordsets |
|
(because Forth systems are allowed to provide only some words of them). |
|
|
|
The @file{ans-report.fs} tool makes it easy for you to determine which |
|
words from which wordset and which non-ANS words your application |
|
uses. You simply have to include @file{ans-report.fs} before loading the |
|
program you want to check. After loading your program, you can get the |
|
report with @code{print-ans-report}. A typical use is to run this as |
|
batch job like this: |
|
@example |
|
gforth ans-report.fs myprog.fs -e "print-ans-report bye" |
|
@end example |
|
|
|
The output looks like this (for @file{compat/control.fs}): |
|
@example |
|
The program uses the following words |
|
from CORE : |
|
: POSTPONE THEN ; immediate ?dup IF 0= |
|
from BLOCK-EXT : |
|
\ |
|
from FILE : |
|
( |
|
@end example |
|
|
|
@subsection Caveats |
|
|
|
Note that @file{ans-report.fs} just checks which words are used, not whether |
|
they are used in an ANS Forth conforming way! |
|
|
|
Some words are defined in several wordsets in the |
|
standard. @file{ans-report.fs} reports them for only one of the |
|
wordsets, and not necessarily the one you expect. It depends on usage |
|
which wordset is the right one to specify. E.g., if you only use the |
|
compilation semantics of @code{S"}, it is a Core word; if you also use |
|
its interpretation semantics, it is a File word. |
|
|
|
|
|
@node ANS conformance, Model, Tools, Top |
@chapter ANS conformance |
@chapter ANS conformance |
|
|
To the best of our knowledge, Gforth is an |
To the best of our knowledge, Gforth is an |
Line 2262 processor-dependent. Gforth's alignment
|
Line 2783 processor-dependent. Gforth's alignment
|
|
|
@item @code{EMIT} and non-graphic characters: |
@item @code{EMIT} and non-graphic characters: |
The character is output using the C library function (actually, macro) |
The character is output using the C library function (actually, macro) |
@code{putchar}. |
@code{putc}. |
|
|
@item character editing of @code{ACCEPT} and @code{EXPECT}: |
@item character editing of @code{ACCEPT} and @code{EXPECT}: |
This is modeled on the GNU readline library (@pxref{Readline |
This is modeled on the GNU readline library (@pxref{Readline |
Line 2282 installation-dependent. Currently a char
|
Line 2803 installation-dependent. Currently a char
|
|
|
@item character-set extensions and matching of names: |
@item character-set extensions and matching of names: |
Any character except the ASCII NUL charcter can be used in a |
Any character except the ASCII NUL charcter can be used in a |
name. Matching is case-insensitive. The matching is performed using the |
name. Matching is case-insensitive (except in @code{TABLE}s. The |
C function @code{strncasecmp}, whose function is probably influenced by |
matching is performed using the C function @code{strncasecmp}, whose |
the locale. E.g., the @code{C} locale does not know about accents and |
function is probably influenced by the locale. E.g., the @code{C} locale |
umlauts, so they are matched case-sensitively in that locale. For |
does not know about accents and umlauts, so they are matched |
portability reasons it is best to write programs such that they work in |
case-sensitively in that locale. For portability reasons it is best to |
the @code{C} locale. Then one can use libraries written by a Polish |
write programs such that they work in the @code{C} locale. Then one can |
programmer (who might use words containing ISO Latin-2 encoded |
use libraries written by a Polish programmer (who might use words |
characters) and by a French programmer (ISO Latin-1) in the same program |
containing ISO Latin-2 encoded characters) and by a French programmer |
(of course, @code{WORDS} will produce funny results for some of the |
(ISO Latin-1) in the same program (of course, @code{WORDS} will produce |
words (which ones, depends on the font you are using)). Also, the locale |
funny results for some of the words (which ones, depends on the font you |
you prefer may not be available in other operating systems. Hopefully, |
are using)). Also, the locale you prefer may not be available in other |
Unicode will solve these problems one day. |
operating systems. Hopefully, Unicode will solve these problems one day. |
|
|
@item conditions under which control characters match a space delimiter: |
@item conditions under which control characters match a space delimiter: |
If @code{WORD} is called with the space character as a delimiter, all |
If @code{WORD} is called with the space character as a delimiter, all |
Line 2326 The error string is stored into the vari
|
Line 2847 The error string is stored into the vari
|
@code{-2 throw} is performed. |
@code{-2 throw} is performed. |
|
|
@item input line terminator: |
@item input line terminator: |
For interactive input, @kbd{C-m} and @kbd{C-j} terminate lines. One of |
For interactive input, @kbd{C-m} (CR) and @kbd{C-j} (LF) terminate |
these characters is typically produced when you type the @kbd{Enter} or |
lines. One of these characters is typically produced when you type the |
@kbd{Return} key. |
@kbd{Enter} or @kbd{Return} key. |
|
|
@item maximum size of a counted string: |
@item maximum size of a counted string: |
@code{s" /counted-string" environment? drop .}. Currently 255 characters |
@code{s" /counted-string" environment? drop .}. Currently 255 characters |
Line 2349 change it from within Gforth. However, t
|
Line 2870 change it from within Gforth. However, t
|
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 |
@code{EMIT} and @code{TYPE} output to the file-id stored in the value |
from within Gforth, but typically from the command line that starts |
@code{outfile-id} (@code{stdout} by default). Gforth uses buffered |
Gforth. Gforth uses buffered output, so output on a terminal does not |
output, so output on a terminal does not become visible before the next |
become visible before the next newline or buffer overflow. Output on |
newline or buffer overflow. Output on non-terminals is invisible until |
non-terminals is invisible until the buffer overflows. |
the buffer overflows. |
|
|
@item methods of dictionary compilation: |
@item methods of dictionary compilation: |
What are we expected to document here? |
What are we expected to document here? |
Line 2389 string.
|
Line 2910 string.
|
@code{1 chars .}. 1 on all current ports. |
@code{1 chars .}. 1 on all current ports. |
|
|
@item size of the keyboard terminal buffer: |
@item size of the keyboard terminal buffer: |
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 |
Line 2401 shared with @code{WORD}.
|
Line 2922 shared with @code{WORD}.
|
|
|
@item size of the scratch area returned by @code{PAD}: |
@item size of the scratch area returned by @code{PAD}: |
The remainder of dictionary space. You can even use the unused part of |
The remainder of dictionary space. You can even use the unused part of |
the data stack space. The current size can be computed with @code{sp@ |
the data stack space. The current size can be computed with @code{sp@@ |
pad - .}. |
pad - .}. |
|
|
@item system case-sensitivity characteristics: |
@item system case-sensitivity characteristics: |
Dictionary searches are case insensitive. However, as explained above |
Dictionary searches are case insensitive (except in |
under @i{character-set extensions}, the matching for non-ASCII |
@code{TABLE}s). However, as explained above under @i{character-set |
characters is determined by the locale you are using. In the default |
extensions}, the matching for non-ASCII characters is determined by the |
@code{C} locale all non-ASCII characters are matched case-sensitively. |
locale you are using. In the default @code{C} locale all non-ASCII |
|
characters are matched case-sensitively. |
|
|
@item system prompt: |
@item system prompt: |
@code{ ok} in interpret state, @code{ compiled} in compile state. |
@code{ ok} in interpret state, @code{ compiled} in compile state. |
Line 2425 the choice to @code{gcc} (what to use fo
|
Line 2947 the choice to @code{gcc} (what to use fo
|
On two's complement machines, arithmetic is performed modulo |
On two's complement machines, arithmetic is performed modulo |
2**bits-per-cell for single arithmetic and 4**bits-per-cell for double |
2**bits-per-cell for single arithmetic and 4**bits-per-cell for double |
arithmetic (with appropriate mapping for signed types). Division by zero |
arithmetic (with appropriate mapping for signed types). Division by zero |
typically results in a @code{-55 throw} (floatingpoint unidentified |
typically results in a @code{-55 throw} (Floating-point unidentified |
fault), although a @code{-10 throw} (divide by zero) would be more |
fault), although a @code{-10 throw} (divide by zero) would be more |
appropriate. |
appropriate. |
|
|
Line 2442 No.
|
Line 2964 No.
|
@table @i |
@table @i |
|
|
@item a name is neither a word nor a number: |
@item a name is neither a word nor a number: |
@code{-13 throw} (Undefined word) |
@code{-13 throw} (Undefined word). Actually, @code{-13 bounce}, which |
|
preserves the data and FP stack, so you don't lose more work than |
|
necessary. |
|
|
@item a definition name exceeds the maximum length allowed: |
@item a definition name exceeds the maximum length allowed: |
@code{-19 throw} (Word name too long) |
@code{-19 throw} (Word name too long) |
Line 2459 flow words, and issue a @code{ABORT"} or
|
Line 2983 flow words, and issue a @code{ABORT"} or
|
mismatch). |
mismatch). |
|
|
@item attempting to obtain the execution token of a word with undefined execution semantics: |
@item attempting to obtain the execution token of a word with undefined execution semantics: |
You get an execution token representing the compilation semantics |
@code{-14 throw} (Interpreting a compile-only word). In some cases, you |
instead. |
get an execution token for @code{compile-only-error} (which performs a |
|
@code{-14 throw} when executed). |
|
|
@item dividing by zero: |
@item dividing by zero: |
typically results in a @code{-55 throw} (floating point unidentified |
typically results in a @code{-55 throw} (floating point unidentified |
Line 2481 error appears at a different place when
|
Line 3006 error appears at a different place when
|
|
|
@item interpreting a word with undefined interpretation semantics: |
@item interpreting a word with undefined interpretation semantics: |
For some words, we defined interpretation semantics. For the others: |
For some words, we defined interpretation semantics. For the others: |
@code{-14 throw} (Interpreting a compile-only word). Note that this is |
@code{-14 throw} (Interpreting a compile-only word). |
checked only by the outer (aka text) interpreter; if the word is |
|
@code{execute}d in some other way, it will typically perform it's |
|
compilation semantics even in interpret state. (We could change @code{'} |
|
and relatives not to give the xt of such words, but we think that would |
|
be too restrictive). |
|
|
|
@item modifying the contents of the input buffer or a string literal: |
@item modifying the contents of the input buffer or a string literal: |
These are located in writable memory and can be modified. |
These are located in writable memory and can be modified. |
Line 2513 underflow) is performed. Apart from that
|
Line 3033 underflow) is performed. Apart from that
|
underflows can result in similar behaviour as overflows (of adjacent |
underflows can result in similar behaviour as overflows (of adjacent |
stacks). |
stacks). |
|
|
@item unexepected end of the input buffer, resulting in an attempt to use a zero-length string as a name: |
@item unexpected end of the input buffer, resulting in an attempt to use a zero-length string as a name: |
@code{Create} and its descendants perform a @code{-16 throw} (Attempt to |
@code{Create} and its descendants perform a @code{-16 throw} (Attempt to |
use zero-length string as a name). Words like @code{'} probably will not |
use zero-length string as a name). Words like @code{'} probably will not |
find what they search. Note that it is possible to create zero-length |
find what they search. Note that it is possible to create zero-length |
Line 2523 names with @code{nextname} (should it no
|
Line 3043 names with @code{nextname} (should it no
|
The next invocation of a parsing word returns a string wih length 0. |
The next invocation of a parsing word returns a string wih length 0. |
|
|
@item @code{RECURSE} appears after @code{DOES>}: |
@item @code{RECURSE} appears after @code{DOES>}: |
Compiles a recursive call to the defining word not to the defined word. |
Compiles a recursive call to the defining word, not to the defined word. |
|
|
@item argument input source different than current input source for @code{RESTORE-INPUT}: |
@item argument input source different than current input source for @code{RESTORE-INPUT}: |
@code{-12 THROW}. Note that, once an input file is closed (e.g., because |
@code{-12 THROW}. Note that, once an input file is closed (e.g., because |
Line 2532 reused. Therefore, restoring an input so
|
Line 3052 reused. Therefore, restoring an input so
|
closed file may lead to unpredictable results instead of a @code{-12 |
closed file may lead to unpredictable results instead of a @code{-12 |
THROW}. |
THROW}. |
|
|
In the future, Gforth may be able to retore input source specifications |
In the future, Gforth may be able to restore input source specifications |
from other than the current input soruce. |
from other than the current input soruce. |
|
|
@item data space containing definitions gets de-allocated: |
@item data space containing definitions gets de-allocated: |
Line 2560 stack items are loop control parameters
|
Line 3080 stack items are loop control parameters
|
@code{abort" last word was headerless"}. |
@code{abort" last word was headerless"}. |
|
|
@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) (unless name was defined by |
|
@code{CONSTANT}; then it just changes the constant). |
|
|
@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) |
Line 2570 Gforth behaves as if they were of the sa
|
Line 3091 Gforth behaves as if they were of the sa
|
the behaviour by interpreting all parameters as, e.g., signed. |
the behaviour by interpreting all parameters as, e.g., signed. |
|
|
@item @code{POSTPONE} or @code{[COMPILE]} applied to @code{TO}: |
@item @code{POSTPONE} or @code{[COMPILE]} applied to @code{TO}: |
Assume @code{: X POSTPONE TO ; IMMEDIATE}. @code{X} is equivalent to |
Assume @code{: X POSTPONE TO ; IMMEDIATE}. @code{X} performs the |
@code{TO}. |
compilation semantics of @code{TO}. |
|
|
@item String longer than a counted string returned by @code{WORD}: |
@item String longer than a counted string returned by @code{WORD}: |
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, |
Line 2610 and you can give commands to Gforth inte
|
Line 3131 and you can give commands to Gforth inte
|
available depend on how you invoke Gforth. |
available depend on how you invoke Gforth. |
|
|
@item program data space available: |
@item program data space available: |
@code{sp@ here - .} gives the space remaining for dictionary and data |
@code{sp@@ here - .} gives the space remaining for dictionary and data |
stack together. |
stack together. |
|
|
@item return stack space available: |
@item return stack space available: |
Line 2618 By default 16 KBytes. The default can be
|
Line 3139 By default 16 KBytes. The default can be
|
switch (@pxref{Invocation}) when Gforth starts up. |
switch (@pxref{Invocation}) when Gforth starts up. |
|
|
@item stack space available: |
@item stack space available: |
@code{sp@ here - .} gives the space remaining for dictionary and data |
@code{sp@@ here - .} gives the space remaining for dictionary and data |
stack together. |
stack together. |
|
|
@item system dictionary space required, in address units: |
@item system dictionary space required, in address units: |
Line 2744 The least significant cell of @var{d} is
|
Line 3265 The least significant cell of @var{d} is
|
The codes -256@minus{}-511 are used for reporting signals (see |
The codes -256@minus{}-511 are used for reporting signals (see |
@file{errore.fs}). The codes -512@minus{}-2047 are used for OS errors |
@file{errore.fs}). The codes -512@minus{}-2047 are used for OS errors |
(for file and memory allocation operations). The mapping from OS error |
(for file and memory allocation operations). The mapping from OS error |
numbers to throw code is -512@minus{}@var{errno}. One side effect of |
numbers to throw code is -512@minus{}@code{errno}. One side effect of |
this mapping is that undefined OS errors produce a message with a |
this mapping is that undefined OS errors produce a message with a |
strange number; e.g., @code{-1000 THROW} results in @code{Unknown error |
strange number; e.g., @code{-1000 THROW} results in @code{Unknown error |
488} on my system. |
488} on my system. |
Line 2861 of open files available. This should not
|
Line 3382 of open files available. This should not
|
@code{/line}. Currently 255. |
@code{/line}. Currently 255. |
|
|
@item methods of mapping block ranges to files: |
@item methods of mapping block ranges to files: |
Currently, the block words automatically access the file |
By default, blocks are accessed in the file @file{blocks.fb} in the |
@file{blocks.fb} in the currend working directory. More sophisticated |
current working directory. The file can be switched with @code{USE}. |
methods could be implemented if there is demand (and a volunteer). |
|
|
|
@item number of string buffers provided by @code{S"}: |
@item number of string buffers provided by @code{S"}: |
1 |
1 |
Line 2959 with the command-line option @code{-f}.
|
Line 3479 with the command-line option @code{-f}.
|
@table @i |
@table @i |
|
|
@item @code{df@@} or @code{df!} used with an address that is not double-float aligned: |
@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 |
System-dependent. Typically results in a @code{-23 THROW} like other |
alignment violations. |
alignment violations. |
|
|
@item @code{f@@} or @code{f!} used with an address that is not float aligned: |
@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 |
System-dependent. Typically results in a @code{-23 THROW} like other |
alignment violations. |
alignment violations. |
|
|
@item Floating-point result out of range: |
@item Floating-point result out of range: |
Line 3111 intended as throw codes. They typically
|
Line 3631 intended as throw codes. They typically
|
@table @i |
@table @i |
|
|
@item ending sequence for input following @code{;code} and @code{code}: |
@item ending sequence for input following @code{;code} and @code{code}: |
Not implemented (yet). |
@code{end-code} |
|
|
@item manner of processing input following @code{;code} and @code{code}: |
@item manner of processing input following @code{;code} and @code{code}: |
Not implemented (yet). |
The @code{assembler} vocabulary is pushed on the search order stack, and |
|
the input is processed by the text interpreter, (starting) in interpret |
|
state. |
|
|
@item search order capability for @code{EDITOR} and @code{ASSEMBLER}: |
@item search order capability for @code{EDITOR} and @code{ASSEMBLER}: |
Not implemented (yet). If they were implemented, they would use the |
The ANS Forth search order word set. |
search order wordset. |
|
|
|
@item source and format of display by @code{SEE}: |
@item source and format of display by @code{SEE}: |
The source for @code{see} is the intermediate code used by the inner |
The source for @code{see} is the intermediate code used by the inner |
Line 3147 unlucky, this ambiguous condition is not
|
Line 3668 unlucky, this ambiguous condition is not
|
Not implemented (yet). |
Not implemented (yet). |
|
|
@item @var{name} not defined via @code{CREATE}: |
@item @var{name} not defined via @code{CREATE}: |
@code{;code} is not implemented (yet). If it were, it would behave like |
@code{;code} behaves like @code{DOES>} in this respect, i.e., it changes |
@code{DOES>} in this respect, i.e., change the execution semantics of |
the execution semantics of the last defined word no matter how it was |
the last defined word no matter how it was defined. |
defined. |
|
|
@item @code{POSTPONE} applied to @code{[IF]}: |
@item @code{POSTPONE} applied to @code{[IF]}: |
After defining @code{: X POSTPONE [IF] ; IMMEDIATE}. @code{X} is |
After defining @code{: X POSTPONE [IF] ; IMMEDIATE}. @code{X} is |
Line 3229 that are otherwise written in C, C++, or
|
Line 3750 that are otherwise written in C, C++, or
|
|
|
The Forth system ATLAST provides facilities for embedding it into |
The Forth system ATLAST provides facilities for embedding it into |
applications; unfortunately it has several disadvantages: most |
applications; unfortunately it has several disadvantages: most |
implorantly, it is not based on ANS Forth, and it is apparently dead |
importantly, it is not based on ANS Forth, and it is apparently dead |
(i.e., not developed further and not supported). The facilities |
(i.e., not developed further and not supported). The facilities |
provided by Gforth in this area are inspired by ATLASTs facilities, so |
provided by Gforth in this area are inspired by ATLASTs facilities, so |
making the switch should not be hard. |
making the switch should not be hard. |
Line 3246 prefix @code{forth_}. (Global symbols th
|
Line 3767 prefix @code{forth_}. (Global symbols th
|
prefix @code{gforth_}). |
prefix @code{gforth_}). |
|
|
You can include the declarations of Forth types and the functions and |
You can include the declarations of Forth types and the functions and |
variables of the interface with @code{include <forth.h>}. |
variables of the interface with @code{#include <forth.h>}. |
|
|
Types. |
Types. |
|
|
Line 3744 relative Win32- NT eforth
|
Line 4265 relative Win32- NT eforth
|
time Gforth Forth Forth eforth +opt PFE Forth TILE |
time Gforth Forth Forth eforth +opt PFE Forth TILE |
sieve 1.00 1.39 1.14 1.39 0.85 1.58 3.18 8.58 |
sieve 1.00 1.39 1.14 1.39 0.85 1.58 3.18 8.58 |
bubble 1.00 1.31 1.41 1.48 0.88 1.50 3.88 |
bubble 1.00 1.31 1.41 1.48 0.88 1.50 3.88 |
matmul 1.00 1.47 1.35 1.46 1.16 1.58 4.09 |
matmul 1.00 1.47 1.35 1.46 0.74 1.58 4.09 |
fib 1.00 1.52 1.34 1.22 1.13 1.74 2.99 4.30 |
fib 1.00 1.52 1.34 1.22 0.86 1.74 2.99 4.30 |
@end example |
@end example |
|
|
You may find the good performance of Gforth compared with the systems |
You may find the good performance of Gforth compared with the systems |
Line 3817 one of Gforth's first users, in mid-1993
|
Line 4338 one of Gforth's first users, in mid-1993
|
with their continuous feedback. Lennart Benshop contributed |
with their continuous feedback. Lennart Benshop contributed |
@file{glosgen.fs}, while Stuart Ramsden has been working on automatic |
@file{glosgen.fs}, while Stuart Ramsden has been working on automatic |
support for calling C libraries. Helpful comments also came from Paul |
support for calling C libraries. Helpful comments also came from Paul |
Kleinrubatscher, Christian Pirker, Dirk Zoller and Marcel Hendrix. |
Kleinrubatscher, Christian Pirker, Dirk Zoller, Marcel Hendrix, John |
|
Wavrik, Barrie Stott and Marc de Groot. |
|
|
Gforth also owes a lot to the authors of the tools we used (GCC, CVS, |
Gforth also owes a lot to the authors of the tools we used (GCC, CVS, |
and autoconf, among others), and to the creators of the Internet: Gforth |
and autoconf, among others), and to the creators of the Internet: Gforth |