Diff for /gforth/Attic/gforth.ds between versions 1.21 and 1.42

version 1.21, 1995/11/07 18:06:41 version 1.42, 1997/01/14 16:30:50
Line 7 Line 7
 @comment %**end of header (This is for running Texinfo on a region.)  @comment %**end of header (This is for running Texinfo on a region.)
   
 @ifinfo  @ifinfo
 This file documents Gforth 0.1  This file documents Gforth 0.2
   
 Copyright @copyright{} 1995 Free Software Foundation, Inc.  Copyright @copyright{} 1995,1996 Free Software Foundation, Inc.
   
      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 36  Copyright @copyright{} 1995 Free Softwar Line 36  Copyright @copyright{} 1995 Free Softwar
      of in the original English.       of in the original English.
 @end ifinfo  @end ifinfo
   
   @finalout
 @titlepage  @titlepage
 @sp 10  @sp 10
 @center @titlefont{Gforth Manual}  @center @titlefont{Gforth Manual}
 @sp 2  @sp 2
 @center for version 0.1  @center for version 0.2
 @sp 2  @sp 2
 @center Anton Ertl  @center Anton Ertl
   @center Bernd Paysan
 @sp 3  @sp 3
 @center This manual is under construction  @center This manual is under construction
   
 @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{} 1995 Free Software Foundation, Inc.  Copyright @copyright{} 1995,1996 Free Software Foundation, Inc.
   
 @comment !! Published by ... or You can get a copy of this manual ...  @comment !! Published by ... or You can get a copy of this manual ...
   
Line 75  Copyright @copyright{} 1995 Free Softwar Line 77  Copyright @copyright{} 1995 Free Softwar
 @node Top, License, (dir), (dir)  @node Top, License, (dir), (dir)
 @ifinfo  @ifinfo
 Gforth 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 0.1.  personal machines. This manual corresponds to version 0.2.
 @end ifinfo  @end ifinfo
   
 @menu  @menu
Line 84  personal machines. This manual correspon Line 86  personal machines. This manual correspon
 * 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.
 * 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 Gforth  * Origin::                      Authors and 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 487  library.  If this is what you want to do Line 491  library.  If this is what you want to do
 Public License instead of this License.  Public License instead of this License.
   
 @iftex  @iftex
   @node    Preface
   @comment node-name,     next,           previous, up
 @unnumbered Preface  @unnumbered Preface
   @cindex Preface
 This manual documents Gforth. 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.
Line 555  can also get it from Global Engineering Line 562  can also get it from Global Engineering
 for publication is available electronically and for free in some MS Word  for publication is available electronically and for free in some MS Word
 format, and it has been converted to HTML. Some pointers to these  format, and it has been converted to HTML. Some pointers to these
 versions can be found through  versions can be found through
 http://www.complang.tuwien.ac.at/projects/forth.html.  @*@file{http://www.complang.tuwien.ac.at/projects/forth.html}.
   
 @cite{Forth: The new model} by Jack Woehr (Prentice-Hall, 1993) is an  @cite{Forth: The new model} by Jack Woehr (Prentice-Hall, 1993) is an
 introductory book based on a draft version of the standard. It does not  introductory book based on a draft version of the standard. It does not
 cover the whole standard. It also contains interesting background  cover the whole standard. It also contains interesting background
 information (Jack Woehr was in the ANS Forth Technical Committe). It is  information (Jack Woehr was in the ANS Forth Technical Committee). It is
 not appropriate for complete newbies, but programmers experienced in  not appropriate for complete newbies, but programmers experienced in
 other languages should find it ok.  other languages should find it ok.
   
Line 594  Loads the Forth image @var{file} instead Line 601  Loads the Forth image @var{file} instead
   
 @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).
   
 @item --dictionary-size @var{size}  @item --dictionary-size @var{size}
 @item -m @var{size}  @item -m @var{size}
Line 634  default specified in the image (typicall Line 641  default specified in the image (typicall
   
 As explained above, the image-specific command-line arguments for the  As explained above, the image-specific command-line arguments for the
 default image @file{gforth.fi} consist of a sequence of filenames and  default image @file{gforth.fi} consist of a sequence of filenames and
 @code{-e @var{forth-code}} options that are interpreted in the seqence  @code{-e @var{forth-code}} options that are interpreted in the sequence
 in which they are given. The @code{-e @var{forth-code}} or  in which they are given. The @code{-e @var{forth-code}} or
 @code{--evaluate @var{forth-code}} option evaluates the forth  @code{--evaluate @var{forth-code}} option evaluates the forth
 code. This option takes only one argument; if you want to evaluate more  code. This option takes only one argument; if you want to evaluate more
Line 642  Forth words, you have to quote them or u Line 649  Forth words, you have to quote them or u
 after processing the command line (instead of entering interactive mode)  after processing the command line (instead of entering interactive mode)
 append @code{-e bye} to the command line.  append @code{-e bye} to the command line.
   
   If you have several versions of Gforth installed, @code{gforth} will
   invoke the version that was installed last. @code{gforth-@var{version}}
   invokes a specific version. You may want to use the option
   @code{--path}, if your environment contains the variable
   @code{GFORTHPATH}.
   
 Not yet implemented:  Not yet implemented:
 On startup the system first executes the system initialization file  On startup the system first executes the system initialization file
 (unless the option @code{--no-init-file} is given; note that the system  (unless the option @code{--no-init-file} is given; note that the system
Line 650  the user initialization file @file{.gfor Line 663  the user initialization file @file{.gfor
 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).
   
 @node Words, ANS conformance, Invocation, Top  @node Words, Tools, Invocation, Top
 @chapter Forth Words  @chapter Forth Words
   
 @menu  @menu
Line 661  then in @file{~}, then in the normal pat Line 674  then in @file{~}, then in the normal pat
 * Control Structures::            * Control Structures::          
 * Locals::                        * Locals::                      
 * Defining Words::                * Defining Words::              
   * Tokens for Words::            
 * Wordlists::                     * Wordlists::                   
 * Files::                         * Files::                       
 * Blocks::                        * Blocks::                      
Line 743  double sized signed integer Line 757  double sized signed integer
 @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 760  Execution token, same size as Cell Line 774  Execution token, same size as Cell
 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
   @item "
   string in the input stream (not the stack). The terminating character is
   a blank by default. If it is not a blank, it is shown in @code{<>}
   quotes.
   
 @end table  @end table
   
 @node Arithmetic, Stack Manipulation, Notation, Words  @node Arithmetic, Stack Manipulation, Notation, Words
Line 836  doc-dmax Line 855  doc-dmax
 The format of floating point numbers recognized by the outer (aka text)  The format of floating point numbers recognized by the outer (aka text)
 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} is 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 1130  system that only supplies @code{THEN} is Line 1149  system that only supplies @code{THEN} is
 Forth's @code{THEN} has the meaning 2b, whereas @code{THEN} in Pascal  Forth's @code{THEN} has the meaning 2b, whereas @code{THEN} in Pascal
 and many other programming languages has the meaning 3d.]  and many other programming languages has the meaning 3d.]
   
 We also provide the words @code{?dup-if} and @code{?dup-0=-if}, so you  Gforth also provides the words @code{?dup-if} and @code{?dup-0=-if}, so
 can avoid using @code{?dup}.  you can avoid using @code{?dup}. Using these alternatives is also more
   efficient than using @code{?dup}. Definitions in plain standard Forth
   for @code{ENDIF}, @code{?DUP-IF} and @code{?DUP-0=-IF} are provided in
   @file{compat/control.fs}.
   
 @example  @example
 @var{n}  @var{n}
Line 1223  arithmetic). This behaviour is usually n Line 1245  arithmetic). This behaviour is usually n
 Gforth offers @code{+DO} and @code{U+DO} (as replacements for  Gforth offers @code{+DO} and @code{U+DO} (as replacements for
 @code{?DO}), which do not enter the loop if @var{start} is greater than  @code{?DO}), which do not enter the loop if @var{start} is greater than
 @var{limit}; @code{+DO} is for signed loop parameters, @code{U+DO} for  @var{limit}; @code{+DO} is for signed loop parameters, @code{U+DO} for
 unsigned loop parameters. These words can be implemented easily on  unsigned loop parameters.
 standard systems, so using them does not make your programs hard to  
 port; e.g.:  
 @example  
 : +DO ( compile-time: -- do-sys; run-time: n1 n2 -- )  
     POSTPONE over POSTPONE min POSTPONE ?DO ; immediate  
 @end example  
   
 @code{LOOP} can be replaced with @code{@var{n} +LOOP}; this updates the  @code{LOOP} can be replaced with @code{@var{n} +LOOP}; this updates the
 index by @var{n} instead of by 1. The loop is terminated when the border  index by @var{n} instead of by 1. The loop is terminated when the border
Line 1257  between @var{limit+1} and @var{limit} is Line 1273  between @var{limit+1} and @var{limit} is
   
 @code{ 0 0 -DO  i .  1 -LOOP}  prints nothing  @code{ 0 0 -DO  i .  1 -LOOP}  prints nothing
   
 Another alternative is @code{@var{n} S+LOOP}, where the negative  Unfortunately, @code{+DO}, @code{U+DO}, @code{-DO}, @code{U-DO} and
 case behaves symmetrical to the positive case:  @code{-LOOP} are not in the ANS Forth standard. However, an
   implementation for these words that uses only standard words is provided
 @code{-2 0 -DO  i .  -1 S+LOOP}  prints @code{0 -1}  in @file{compat/loops.fs}.
   
 The loop is terminated when the border between @var{limit@minus{}sgn(n)}  
 and @var{limit} is crossed. Unfortunately, neither @code{-LOOP} nor  
 @code{S+LOOP} are part of the ANS Forth standard, and they are not easy  
 to implement using standard words. If you want to write standard  
 programs, just avoid counting down.  
   
 @code{?DO} can also be replaced by @code{DO}. @code{DO} always enters  @code{?DO} can also be replaced by @code{DO}. @code{DO} always enters
 the loop, independent of the loop parameters. Do not use @code{DO}, even  the loop, independent of the loop parameters. Do not use @code{DO}, even
Line 1289  This is the preferred loop of native cod Line 1299  This is the preferred loop of native cod
 lazy to optimize @code{?DO} loops properly. In Gforth, 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. To avoid problems, don't use @code{FOR}
   loops.
   
 @node Arbitrary control structures, Calls and returns, Counted Loops, Control Structures  @node Arbitrary control structures, Calls and returns, Counted Loops, Control Structures
 @subsection Arbitrary control structures  @subsection Arbitrary control structures
Line 1325  doc-else Line 1336  doc-else
 doc-while  doc-while
 doc-repeat  doc-repeat
   
   Gforth adds some more control-structure words:
   
   doc-endif
   doc-?dup-if
   doc-?dup-0=-if
   
 Counted loop words constitute a separate group of words:  Counted loop words constitute a separate group of words:
   
 doc-?do  doc-?do
Line 1335  doc-u-do Line 1352  doc-u-do
 doc-do  doc-do
 doc-for  doc-for
 doc-loop  doc-loop
 doc-s+loop  
 doc-+loop  doc-+loop
 doc--loop  doc--loop
 doc-next  doc-next
Line 1400  while Line 1416  while
 repeat  repeat
 @end example  @end example
   
 That's much easier to read, isn't it? Of course, @code{BEGIN} and  That's much easier to read, isn't it? Of course, @code{REPEAT} and
 @code{WHILE} are predefined, so in this example it would not be  @code{WHILE} are predefined, so in this example it would not be
 necessary to define them.  necessary to define them.
   
Line 1434  laden with restrictions. Therefore, we p Line 1450  laden with restrictions. Therefore, we p
 locals wordset, but also our own, more powerful locals wordset (we  locals wordset, but also our own, more powerful locals wordset (we
 implemented the ANS Forth locals wordset through our locals wordset).  implemented the ANS Forth locals wordset through our locals wordset).
   
   The ideas in this section have also been published in the paper
   @cite{Automatic Scoping of Local Variables} by M. Anton Ertl, presented
   at EuroForth '94; it is available at
   @*@file{http://www.complang.tuwien.ac.at/papers/ertl94l.ps.gz}.
   
 @menu  @menu
 * Gforth locals::                 * Gforth locals::               
 * ANS Forth locals::              * ANS Forth locals::            
Line 1489  Gforth currently supports cells (@code{W Line 1510  Gforth currently supports cells (@code{W
 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
 with @code{TO}. A variable-flavoured local (defined with @code{W^} etc.)  with @code{TO}. A variable-flavoured local (defined with @code{W^} etc.)
 produces its address (which becomes invalid when the variable's scope is  produces its address (which becomes invalid when the variable's scope is
 left). E.g., the standard word @code{emit} can be defined in therms of  left). E.g., the standard word @code{emit} can be defined in terms of
 @code{type} like this:  @code{type} like this:
   
 @example  @example
Line 1548  definition? Which local is meant, if the Line 1569  definition? Which local is meant, if the
 two independent control flow paths?  two independent control flow paths?
   
 This should be enough detail for nearly all users, so you can skip the  This should be enough detail for nearly all users, so you can skip the
 rest of this section. If you relly must know all the gory details and  rest of this section. If you really must know all the gory details and
 options, read on.  options, read on.
   
 In order to implement this rule, the compiler has to know which places  In order to implement this rule, the compiler has to know which places
Line 1601  are entered only through the @code{BEGIN Line 1622  are entered only through the @code{BEGIN
 @code{BEGIN}...@code{UNTIL} loops and it is implemented in our  @code{BEGIN}...@code{UNTIL} loops and it is implemented in our
 compiler. When the branch to the @code{BEGIN} is finally generated by  compiler. When the branch to the @code{BEGIN} is finally generated by
 @code{AGAIN} or @code{UNTIL}, the compiler checks the guess and  @code{AGAIN} or @code{UNTIL}, the compiler checks the guess and
 warns the user if it was too optimisitic:  warns the user if it was too optimistic:
 @example  @example
 IF  IF
   @{ x @}    @{ x @}
Line 1720  E.g., a definition using @code{TO} might Line 1741  E.g., a definition using @code{TO} might
 : 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@ - ?dup     addr1 c@@ addr2 c@@ -
    if     ?dup-if
      unloop exit       unloop exit
    then     then
    addr1 char+ TO addr1     addr1 char+ TO addr1
Line 1743  are initialized with the right value for Line 1764  are initialized with the right value for
  addr1 addr2   addr1 addr2
  u1 u2 min 0    u1 u2 min 0 
  ?do @{ s1 s2 @}   ?do @{ s1 s2 @}
    s1 c@ s2 c@ - ?dup      s1 c@@ s2 c@@ -
    if     ?dup-if
      unloop exit       unloop exit
    then     then
    s1 char+ s2 char+     s1 char+ s2 char+
Line 1917  stack easier. Line 1938  stack easier.
 The whole definition must be in one line.  The whole definition must be in one line.
 @end itemize  @end itemize
   
 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}.
   
 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{compat/anslocal.fs} to implement the
 on the other system.  syntax on the other system.
   
 Note that a syntax shown in the standard, section A.13 looks  Note that a syntax shown in the standard, section A.13 looks
 similar, but is quite different in having the order of locals  similar, but is quite different in having the order of locals
Line 1943  programs harder to read, and easier to m Line 1964  programs harder to read, and easier to m
 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.
   
 @node Defining Words, Wordlists, Locals, Words  @node Defining Words, Tokens for Words, Locals, Words
 @section Defining Words  @section Defining Words
   
 @menu  @menu
 * Values::                        * Simple Defining Words::       
   * Colon Definitions::           
   * User-defined Defining Words::  
   * Supplying names::             
   * Interpretation and Compilation Semantics::  
 @end menu  @end menu
   
 @node Values,  , Defining Words, Defining Words  @node Simple Defining Words, Colon Definitions, Defining Words, Defining Words
 @subsection Values  @subsection Simple Defining Words
   
   doc-constant
   doc-2constant
   doc-fconstant
   doc-variable
   doc-2variable
   doc-fvariable
   doc-create
   doc-user
   doc-value
   doc-to
   doc-defer
   doc-is
   
   @node Colon Definitions, User-defined Defining Words, Simple Defining Words, Defining Words
   @subsection Colon Definitions
   
   @example
   : name ( ... -- ... )
       word1 word2 word3 ;
   @end example
   
   creates a word called @code{name}, that, upon execution, executes
   @code{word1 word2 word3}. @code{name} is a @dfn{(colon) definition}.
   
   The explanation above is somewhat superficial. @xref{Interpretation and
   Compilation Semantics} for an in-depth discussion of some of the issues
   involved.
   
   doc-:
   doc-;
   
   @node User-defined Defining Words, Supplying names, Colon Definitions, Defining Words
   @subsection User-defined Defining Words
   
   You can create new defining words simply by wrapping defining-time code
   around existing defining words and putting the sequence in a colon
   definition.
   
   If you want the words defined with your defining words to behave
   differently from words defined with standard defining words, you can
   write your defining word like this:
   
   @example
   : def-word ( "name" -- )
       Create @var{code1}
   DOES> ( ... -- ... )
       @var{code2} ;
   
   def-word name
   @end example
   
   Technically, this fragment defines a defining word @code{def-word}, and
   a word @code{name}; when you execute @code{name}, the address of the
   body of @code{name} is put on the data stack and @var{code2} is executed
   (the address of the body of @code{name} is the address @code{HERE}
   returns immediately after the @code{CREATE}).
   
   In other words, if you make the following definitions:
   
   @example
   : def-word1 ( "name" -- )
       Create @var{code1} ;
   
   : action1 ( ... -- ... )
       @var{code2} ;
   
   def-word name1
   @end example
   
   Using @code{name1 action1} is equivalent to using @code{name}.
   
   E.g., you can implement @code{Constant} in this way:
   
   @example
   : constant ( w "name" -- )
       create ,
   DOES> ( -- w )
       @@ ;
   @end example
   
   When you create a constant with @code{5 constant five}, first a new word
   @code{five} is created, then the value 5 is laid down in the body of
   @code{five} with @code{,}. When @code{five} is invoked, the address of
   the body is put on the stack, and @code{@@} retrieves the value 5.
   
   In the example above the stack comment after the @code{DOES>} specifies
   the stack effect of the defined words, not the stack effect of the
   following code (the following code expects the address of the body on
   the top of stack, which is not reflected in the stack comment). This is
   the convention that I use and recommend (it clashes a bit with using
   locals declarations for stack effect specification, though).
   
   @subsubsection Applications of @code{CREATE..DOES>}
   
   You may wonder how to use this feature. Here are some usage patterns:
   
   When you see a sequence of code occurring several times, and you can
   identify a meaning, you will factor it out as a colon definition. When
   you see similar colon definitions, you can factor them using
   @code{CREATE..DOES>}. E.g., an assembler usually defines several words
   that look very similar:
   @example
   : ori, ( reg-target reg-source n -- )
       0 asm-reg-reg-imm ;
   : andi, ( reg-target reg-source n -- )
       1 asm-reg-reg-imm ;
   @end example
   
   This could be factored with:
   @example
   : reg-reg-imm ( op-code -- )
       create ,
   DOES> ( reg-target reg-source n -- )
       @@ asm-reg-reg-imm ;
   
   0 reg-reg-imm ori,
   1 reg-reg-imm andi,
   @end example
   
   Another view of @code{CREATE..DOES>} is to consider it as a crude way to
   supply a part of the parameters for a word (known as @dfn{currying} in
   the functional language community). E.g., @code{+} needs two
   parameters. Creating versions of @code{+} with one parameter fixed can
   be done like this:
   @example
   : curry+ ( n1 -- )
       create ,
   DOES> ( n2 -- n1+n2 )
       @@ + ;
   
    3 curry+ 3+
   -2 curry+ 2-
   @end example
   
   @subsubsection The gory details of @code{CREATE..DOES>}
   
   doc-does>
   
   This means that you need not use @code{CREATE} and @code{DOES>} in the
   same definition; E.g., you can put the @code{DOES>}-part in a separate
   definition. This allows us to, e.g., select among different DOES>-parts:
   @example
   : does1 
   DOES> ( ... -- ... )
       ... ;
   
   : does2
   DOES> ( ... -- ... )
       ... ;
   
   : def-word ( ... -- ... )
       create ...
       IF
          does1
       ELSE
          does2
       ENDIF ;
   @end example
   
   In a standard program you can apply a @code{DOES>}-part only if the last
   word was defined with @code{CREATE}. In Gforth, the @code{DOES>}-part
   will override the behaviour of the last word defined in any case. In a
   standard program, you can use @code{DOES>} only in a colon
   definition. In Gforth, you can also use it in interpretation state, in a
   kind of one-shot mode:
   @example
   CREATE name ( ... -- ... )
     @var{initialization}
   DOES>
     @var{code} ;
   @end example
   This is equivalent to the standard
   @example
   :noname
   DOES>
       @var{code} ;
   CREATE name EXECUTE ( ... -- ... )
       @var{initialization}
   @end example
   
   You can get the address of the body of a word with
   
   doc->body
   
   @node Supplying names, Interpretation and Compilation Semantics, User-defined Defining Words, Defining Words
   @subsection Supplying names for the defined words
   
   By default, defining words take the names for the defined words from the
   input stream. Sometimes you want to supply the name from a string. You
   can do this with
   
   doc-nextname
   
   E.g.,
   
   @example
   s" foo" nextname create
   @end example
   is equivalent to
   @example
   create foo
   @end example
   
   Sometimes you want to define a word without a name. You can do this with
   
   doc-noname
   
   To make any use of the newly defined word, you need its execution
   token. You can get it with
   
   doc-lastxt
   
   E.g., you can initialize a deferred word with an anonymous colon
   definition:
   @example
   Defer deferred
   noname : ( ... -- ... )
     ... ;
   lastxt IS deferred
   @end example
   
   @code{lastxt} also works when the last word was not defined as
   @code{noname}. 
   
   The standard has also recognized the need for anonymous words and
   provides
   
   doc-:noname
   
   This leaves the execution token for the word on the stack after the
   closing @code{;}. You can rewrite the last example with @code{:noname}:
   @example
   Defer deferred
   :noname ( ... -- ... )
     ... ;
   IS deferred
   @end example
   
   @node Interpretation and Compilation Semantics,  , Supplying names, Defining Words
   @subsection Interpretation and Compilation Semantics
   
   The @dfn{interpretation semantics} of a word are what the text
   interpreter does when it encounters the word in interpret state. It also
   appears in some other contexts, e.g., the execution token returned by
   @code{' @var{word}} identifies the interpretation semantics of
   @var{word} (in other words, @code{' @var{word} execute} is equivalent to
   interpret-state text interpretation of @code{@var{word}}).
   
   The @dfn{compilation semantics} of a word are what the text interpreter
   does when it encounters the word in compile state. It also appears in
   other contexts, e.g, @code{POSTPONE @var{word}} compiles@footnote{In
   standard terminology, ``appends to the current definition''.} the
   compilation semantics of @var{word}.
   
   The standard also talks about @dfn{execution semantics}. They are used
   only for defining the interpretation and compilation semantics of many
   words. By default, the interpretation semantics of a word are to
   @code{execute} its execution semantics, and the compilation semantics of
   a word are to @code{compile,} its execution semantics.@footnote{In
   standard terminology: The default interpretation semantics are its
   execution semantics; the default compilation semantics are to append its
   execution semantics to the execution semantics of the current
   definition.}
   
   You can change the compilation semantics into @code{execute}ing the
   execution semantics with
   
   doc-immediate
   
   You can remove the interpretation semantics of a word with
   
   doc-compile-only
   doc-restrict
   
   Note that ticking (@code{'}) compile-only words gives an error
   (``Interpreting a compile-only word'').
   
 @node Wordlists, Files, Defining Words, Words  Gforth also allows you to define words with arbitrary combinations of
   interpretation and compilation semantics.
   
   doc-interpret/compile:
   
   This feature was introduced for implementing @code{TO} and @code{S"}. I
   recommend that you do not define such words, as cute as they may be:
   they make it hard to get at both parts of the word in some contexts.
   E.g., assume you want to get an execution token for the compilation
   part. Instead, define two words, one that embodies the interpretation
   part, and one that embodies the compilation part.
   
   There is, however, a potentially useful application of this feature:
   Providing differing implementations for the default semantics. While
   this introduces redundancy and is therefore usually a bad idea, a
   performance improvement may be worth the trouble. E.g., consider the
   word @code{foobar}:
   
   @example
   : foobar
       foo bar ;
   @end example
   
   Let us assume that @code{foobar} is called so frequently that the
   calling overhead would take a significant amount of the run-time. We can
   optimize it with @code{interpret/compile:}:
   
   @example
   :noname
      foo bar ;
   :noname
      POSTPONE foo POSTPONE bar ;
   interpret/compile: foobar
   @end example
   
   This definition has the same interpretation semantics and essentially
   the same compilation semantics as the simple definition of
   @code{foobar}, but the implementation of the compilation semantics is
   more efficient with respect to run-time.
   
   Some people try to use state-smart words to emulate the feature provided
   by @code{interpret/compile:} (words are state-smart if they check
   @code{STATE} during execution). E.g., they would try to code
   @code{foobar} like this:
   
   @example
   : foobar
     STATE @@
     IF ( compilation state )
       POSTPONE foo POSTPONE bar
     ELSE
       foo bar
     ENDIF ; immediate
   @end example
   
   While this works if @code{foobar} is processed only by the text
   interpreter, it does not work in other contexts (like @code{'} or
   @code{POSTPONE}). E.g., @code{' foobar} will produce an execution token
   for a state-smart word, not for the interpretation semantics of the
   original @code{foobar}; when you execute this execution token (directly
   with @code{EXECUTE} or indirectly through @code{COMPILE,}) in compile
   state, the result will not be what you expected (i.e., it will not
   perform @code{foo bar}). State-smart words are a bad idea. Simply don't
   write them!
   
   It is also possible to write defining words that define words with
   arbitrary combinations of interpretation and compilation semantics (or,
   preferably, arbitrary combinations of implementations of the default
   semantics). In general, this looks like:
   
   @example
   : def-word
       create-interpret/compile
       @var{code1}
   interpretation>
       @var{code2}
   <interpretation
   compilation>
       @var{code3}
   <compilation ;
   @end example
   
   For a @var{word} defined with @code{def-word}, the interpretation
   semantics are to push the address of the body of @var{word} and perform
   @var{code2}, and the compilation semantics are to push the address of
   the body of @var{word} and perform @var{code3}. E.g., @code{constant}
   can also be defined like this:
   
   @example
   : constant ( n "name" -- )
       create-interpret/compile
       ,
   interpretation> ( -- n )
       @@
   <interpretation
   compilation> ( compilation. -- ; run-time. -- n )
       @@ postpone literal
   <compilation ;
   @end example
   
   doc-create-interpret/compile
   doc-interpretation>
   doc-<interpretation
   doc-compilation>
   doc-<compilation
   
   Note that words defined with @code{interpret/compile:} and
   @code{create-interpret/compile} have an extended header structure that
   differs from other words; however, unless you try to access them with
   plain address arithmetic, you should not notice this. Words for
   accessing the header structure usually know how to deal with this; e.g.,
   @code{' word >body} also gives you the body of a word created with
   @code{create-interpret/compile}.
   
   @node Tokens for Words, Wordlists, Defining Words, Words
   @section Tokens for Words
   
   This chapter describes the creation and use of tokens that represent
   words on the stack (and in data space).
   
   Named words have interpretation and compilation semantics. Unnamed words
   just have execution semantics.
   
   An @dfn{execution token} represents the execution semantics of an
   unnamed word. An execution token occupies one cell. As explained in
   section @ref{Supplying names}, the execution token of the last words
   defined can be produced with
   
   short-lastxt
   
   You can perform the semantics represented by an execution token with
   doc-execute
   You can compile the word with
   doc-compile,
   
   In Gforth, the abstract data type @emph{execution token} is implemented
   as CFA (code field address).
   
   The interpretation semantics of a named word are also represented by an
   execution token. You can get it with
   
   doc-[']
   doc-'
   
   For literals, you use @code{'} in interpreted code and @code{[']} in
   compiled code. Gforth's @code{'} and @code{[']} behave somewhat unusual
   by complaining about compile-only words. To get an execution token for a
   compiling word @var{X}, use @code{COMP' @var{X} drop} or @code{[COMP']
   @var{X} drop}.
   
   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 knowledge, 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 1981  are meant to support a different style o Line 2464  are meant to support a different style o
 tracing/stepping debuggers used in languages with long turn-around  tracing/stepping debuggers used in languages with long turn-around
 times.  times.
   
 A much better (faster) way in fast-compilig languages is to add  A much better (faster) way in fast-compiling languages is to add
 printing code at well-selected places, let the program run, look at  printing code at well-selected places, let the program run, look at
 the output, see where things went wrong, add more printing code, etc.,  the output, see where things went wrong, add more printing code, etc.,
 until the bug is found.  until the bug is found.
Line 2070  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 gcc version and options used.  but also on the @code{gcc} version and options used.
   
 The words Gforth offers encapsulate some system dependences (e.g., the  The words that Gforth offers encapsulate some system dependences (e.g., the
 header structure), so a system-independent assembler may be used in  header structure), so a system-independent assembler may be used in
 Gforth. If you do not have an assembler, you can compile machine code  Gforth. If you do not have an assembler, you can compile machine code
 directly with @code{,} and @code{c,}.  directly with @code{,} and @code{c,}.
Line 2093  These words are rarely used. Therefore t Line 2576  These words are rarely used. Therefore t
 which is usually not loaded (except @code{flush-icache}, which is always  which is usually not loaded (except @code{flush-icache}, which is always
 present). You can load them with @code{require code.fs}.  present). You can load them with @code{require code.fs}.
   
   In the assembly code you will want to refer to the inner interpreter's
   registers (e.g., the data stack pointer) and you may want to use other
   registers for temporary storage. Unfortunately, the register allocation
   is installation-dependent.
   
   The easiest solution is to use explicit register declarations
   (@pxref{Explicit Reg Vars, , Variables in Specified Registers, gcc.info,
   GNU C Manual}) for all of the inner interpreter's registers: You have to
   compile Gforth with @code{-DFORCE_REG} (configure option
   @code{--enable-force-reg}) and the appropriate declarations must be
   present in the @code{machine.h} file (see @code{mips.h} for an example;
   you can find a full list of all declarable register symbols with
   @code{grep register engine.c}). If you give explicit registers to all
   variables that are declared at the beginning of @code{engine()}, you
   should be able to use the other caller-saved registers for temporary
   storage. Alternatively, you can use the @code{gcc} option
   @code{-ffixed-REG} (@pxref{Code Gen Options, , Options for Code
   Generation Conventions, gcc.info, GNU C Manual}) to reserve a register
   (however, this restriction on register allocation may slow Gforth
   significantly).
   
   If this solution is not viable (e.g., because @code{gcc} does not allow
   you to explicitly declare all the registers you need), you have to find
   out by looking at the code where the inner interpreter's registers
   reside and which registers can be used for temporary storage. You can
   get an assembly listing of the engine's code with @code{make engine.s}.
   
   In any case, it is good practice to abstract your assembly code from the
   actual register allocation. E.g., if the data stack pointer resides in
   register @code{$17}, create an alias for this register called @code{sp},
   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) probably 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 2128  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
   
   @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, Words, Top  @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
   
 ANS Forth System  ANS Forth System
 @itemize  @itemize @bullet
 @item providing the Core Extensions word set  @item providing the Core Extensions word set
 @item providing the Block word set  @item providing the Block word set
 @item providing the Block Extensions word set  @item providing the Block Extensions word set
Line 2158  ANS Forth System Line 2725  ANS Forth System
 @item providing the Memory-Allocation word set  @item providing the Memory-Allocation word set
 @item providing the Memory-Allocation Extensions word set (that one's easy)  @item providing the Memory-Allocation Extensions word set (that one's easy)
 @item providing the Programming-Tools word set  @item providing the Programming-Tools word set
 @item providing @code{;code}, @code{AHEAD}, @code{ASSEMBLER}, @code{BYE}, @code{CODE}, @code{CS-PICK}, @code{CS-ROLL}, @code{STATE}, @code{[ELSE]}, @code{[IF]}, @code{[THEN]} from the Programming-Tools Extensions word set  @item providing @code{;CODE}, @code{AHEAD}, @code{ASSEMBLER}, @code{BYE}, @code{CODE}, @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 word set
 @item providing the Search-Order Extensions word set  @item providing the Search-Order Extensions word set
 @item providing the String word set  @item providing the String word set
Line 2216  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 2236  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 2280  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 2303  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 2343  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 2355  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.
   
 @item division rounding:  @item division rounding:
 installation dependent. @code{s" floored" environment? drop .}. We leave  installation dependent. @code{s" floored" environment? drop .}. We leave
 the choice to gcc (what to use for @code{/}) and to you (whether to use  the choice to @code{gcc} (what to use for @code{/}) and to you (whether to use
 @code{fm/mod}, @code{sm/rem} or simply @code{/}).  @code{fm/mod}, @code{sm/rem} or simply @code{/}).
   
 @item values of @code{STATE} when true:  @item values of @code{STATE} when true:
Line 2379  the choice to gcc (what to use for @code Line 2947  the choice to gcc (what to use for @code
 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 2396  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 2413  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 2435  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 2467  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
 names with @code{nextname} (should it not?).  names with @code{nextname} (should it not?).
   
 @item @code{>IN} greater than input buffer:  @item @code{>IN} greater than input buffer:
 The next invocation of a parsing word returns a string wih length 0.  The next invocation of a parsing word returns a string with 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}:
 !!???If the argument input source is a valid input source then it gets  @code{-12 THROW}. Note that, once an input file is closed (e.g., because
 restored. Otherwise causes @code{-12 THROW}, which, unless caught, issues  the end of the file was reached), its source-id may be
 the message "argument type mismatch" and aborts.  reused. Therefore, restoring an input source specification referencing a
   closed file may lead to unpredictable results instead of a @code{-12
   THROW}.
   
   In the future, Gforth may be able to restore input source specifications
   from other than the current input source.
   
 @item data space containing definitions gets de-allocated:  @item data space containing definitions gets de-allocated:
 Deallocation with @code{allot} is not checked. This typically resuls in  Deallocation with @code{allot} is not checked. This typically results in
 memory access faults or execution of illegal instructions.  memory access faults or execution of illegal instructions.
   
 @item data space read/write with incorrect alignment:  @item data space read/write with incorrect alignment:
Line 2509  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 2519  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 2554  Not checked. As usual, you can expect me Line 3126  Not checked. As usual, you can expect me
 None.  None.
   
 @item operator's terminal facilities available:  @item operator's terminal facilities available:
 !!??  After processing the command line, Gforth goes into interactive mode,
   and you can give commands to Gforth interactively. The actual facilities
   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{UNUSED .} gives the remaining dictionary space. The total
 stack together.  dictionary space can be specified with the @code{-m} switch
   (@pxref{Invocation}) when Gforth starts up.
   
 @item return stack space available:  @item return stack space available:
 !!??  You can compute the total return stack space in cells with
   @code{s" RETURN-STACK-CELLS" environment? drop .}. You can specify it at
   startup time with the @code{-r} switch (@pxref{Invocation}).
   
 @item stack space available:  @item stack space available:
 @code{sp@ here - .} gives the space remaining for dictionary and data  You can compute the total data stack space in cells with
 stack together.  @code{s" STACK-CELLS" environment? drop .}. You can specify it at
   startup time with the @code{-d} switch (@pxref{Invocation}).
   
 @item system dictionary space required, in address units:  @item system dictionary space required, in address units:
 Type @code{here forthstart - .} after startup. At the time of this  Type @code{here forthstart - .} after startup. At the time of this
 writing, this gives 70108 (bytes) on a 32-bit system.  writing, this gives 80080 (bytes) on a 32-bit system.
 @end table  @end table
   
   
Line 2690  The least significant cell of @var{d} is Line 3268  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 2715  strange number; e.g., @code{-1000 THROW} Line 3293  strange number; e.g., @code{-1000 THROW}
 @table @i  @table @i
   
 @item encoding of keyboard events (@code{EKEY}):  @item encoding of keyboard events (@code{EKEY}):
 Not yet implemeted.  Not yet implemented.
   
 @item duration of a system clock tick  @item duration of a system clock tick
 System dependent. With respect to @code{MS}, the time is specified in  System dependent. With respect to @code{MS}, the time is specified in
Line 2739  other single-tasking systems, it should Line 3317  other single-tasking systems, it should
 @table @i  @table @i
   
 @item @code{AT-XY} can't be performed on user output device:  @item @code{AT-XY} can't be performed on user output device:
 Largely terminal dependant. No range checks are done on the arguments.  Largely terminal dependent. No range checks are done on the arguments.
 No errors are reported. You may see some garbage appearing, you may see  No errors are reported. You may see some garbage appearing, you may see
 simply nothing happen.  simply nothing happen.
   
Line 2788  System dependent. Gforth just uses the f Line 3366  System dependent. Gforth just uses the f
 @code{FILE-STATUS} returns the most powerful file access mode allowed  @code{FILE-STATUS} returns the most powerful file access mode allowed
 for the file: Either @code{R/O}, @code{W/O} or @code{R/W}. If the file  for the file: Either @code{R/O}, @code{W/O} or @code{R/W}. If the file
 cannot be accessed, @code{R/O BIN} is returned. @code{BIN} is applicable  cannot be accessed, @code{R/O BIN} is returned. @code{BIN} is applicable
 along with the retured mode.  along with the returned mode.
   
 @item input file state after an exception when including source:  @item input file state after an exception when including source:
 All files that are left via the exception are closed.  All files that are left via the exception are closed.
Line 2807  of open files available. This should not Line 3385  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 2882  System dependent; @code{REPRESENT} is im Line 3459  System dependent; @code{REPRESENT} is im
 function @code{ecvt()} and inherits its behaviour in this respect.  function @code{ecvt()} and inherits its behaviour in this respect.
   
 @item rounding or truncation of floating-point numbers:  @item rounding or truncation of floating-point numbers:
 What's the question?!!  System dependent; the rounding behaviour is inherited from the hosting C
   compiler. IEEE-FP-based (i.e., most) systems by default round to
   nearest, and break ties by rounding to even (i.e., such that the last
   bit of the mantissa is 0).
   
 @item size of floating-point stack:  @item size of floating-point stack:
 @code{s" FLOATING-STACK" environment? drop .}. Can be changed at startup  @code{s" FLOATING-STACK" environment? drop .} gives the total size of
 with the command-line option @code{-f}.  the floating-point stack (in floats). You can specify this on startup
   with the command-line option @code{-f} (@pxref{Invocation}).
   
 @item width of floating-point stack:  @item width of floating-point stack:
 @code{1 floats}.  @code{1 floats}.
Line 2902  with the command-line option @code{-f}. Line 3483  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 3054  intended as throw codes. They typically Line 3635  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 3090  unlucky, this ambiguous condition is not Line 3672  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 3142  Not implemented (yet). Line 3724  Not implemented (yet).
 @table @i  @table @i
   
 @item changing the compilation wordlist (during compilation):  @item changing the compilation wordlist (during compilation):
 The definition is put into the wordlist that is the compilation wordlist  The word is entered into the wordlist that was the compilation wordlist
 when @code{REVEAL} is executed (by @code{;}, @code{DOES>},  at the start of the definition. Any changes to the name field (e.g.,
 @code{RECURSIVE}, etc.).  @code{immediate}) or the code field (e.g., when executing @code{DOES>})
   are applied to the latest defined word (as reported by @code{last} or
   @code{lastxt}), if possible, irrespective of the compilation wordlist.
   
 @item search order empty (@code{previous}):  @item search order empty (@code{previous}):
 @code{abort" Vocstack empty"}.  @code{abort" Vocstack empty"}.
Line 3154  when @code{REVEAL} is executed (by @code Line 3738  when @code{REVEAL} is executed (by @code
   
 @end table  @end table
   
   @node Model, Integrating Gforth, ANS conformance, Top
 @node Model, Emacs and Gforth, ANS conformance, Top  
 @chapter Model  @chapter Model
   
 @node Emacs and Gforth, Internals, Model, Top  This chapter has yet to be written. It will contain information, on
   which internal structures you can rely.
   
   @node Integrating Gforth, Emacs and Gforth, Model, Top
   @chapter Integrating Gforth into C programs
   
   This is not yet implemented.
   
   Several people like to use Forth as scripting language for applications
   that are otherwise written in C, C++, or some other language.
   
   The Forth system ATLAST provides facilities for embedding it into
   applications; unfortunately it has several disadvantages: most
   importantly, it is not based on ANS Forth, and it is apparently dead
   (i.e., not developed further and not supported). The facilities
   provided by Gforth in this area are inspired by ATLASTs facilities, so
   making the switch should not be hard.
   
   We also tried to design the interface such that it can easily be
   implemented by other Forth systems, so that we may one day arrive at a
   standardized interface. Such a standard interface would allow you to
   replace the Forth system without having to rewrite C code.
   
   You embed the Gforth interpreter by linking with the library
   @code{libgforth.a} (give the compiler the option @code{-lgforth}).  All
   global symbols in this library that belong to the interface, have the
   prefix @code{forth_}. (Global symbols that are used internally have the
   prefix @code{gforth_}).
   
   You can include the declarations of Forth types and the functions and
   variables of the interface with @code{#include <forth.h>}.
   
   Types.
   
   Variables.
   
   Data and FP Stack pointer. Area sizes.
   
   functions.
   
   forth_init(imagefile)
   forth_evaluate(string) exceptions?
   forth_goto(address) (or forth_execute(xt)?)
   forth_continue() (a corountining mechanism)
   
   Adding primitives.
   
   No checking.
   
   Signals?
   
   Accessing the Stacks
   
   @node Emacs and Gforth, Internals, Integrating Gforth, 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 (included 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}),
 commenting (@kbd{C-x \}) and uncommenting (@kbd{C-u C-x \}) regions and  commenting (@kbd{C-x \}) and uncommenting (@kbd{C-u C-x \}) regions and
Line 3184  Also, if you @code{include} @file{etags. Line 3820  Also, if you @code{include} @file{etags.
 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, @pxref{Select Tags Table,,Selecting a Tags
   Table,emacs, Emacs Manual}). The TAGS file for the preloaded words is
   @file{$(datadir)/gforth/$(VERSION)/TAGS} (e.g.,
   @file{/usr/local/share/gforth/0.2.0/TAGS}).
   
 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}
 file:  file:
Line 3200  file: Line 3839  file:
 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.
   
   The ideas in this section have also been published in the papers
   @cite{ANS fig/GNU/??? Forth} (in German) by Bernd Paysan, presented at
   the Forth-Tagung '93 and @cite{A Portable Forth Engine} by M. Anton
   Ertl, presented at EuroForth '93; the latter is available at
   @*@file{http://www.complang.tuwien.ac.at/papers/ertl93.ps.Z}.
   
 @menu  @menu
 * Portability::                   * Portability::                 
 * Threading::                     * Threading::                   
Line 3233  limitations: GNU C, the version of C pro Line 3878  limitations: GNU C, the version of C pro
 GNU C Manual}). Its labels as values feature (@pxref{Labels as Values, ,  GNU C Manual}). Its labels as values feature (@pxref{Labels as Values, ,
 Labels as Values, gcc.info, GNU C Manual}) makes direct and indirect  Labels as Values, gcc.info, GNU C Manual}) makes direct and indirect
 threading possible, its @code{long long} type (@pxref{Long Long, ,  threading possible, its @code{long long} type (@pxref{Long Long, ,
 Double-Word Integers, gcc.info, GNU C Manual}) corresponds to Forths  Double-Word Integers, gcc.info, GNU C Manual}) corresponds to Forth's
 double numbers. GNU C is available for free on all important (and many  double numbers@footnote{Unfortunately, long longs are not implemented
 unimportant) UNIX machines, VMS, 80386s running MS-DOS, the Amiga, and  properly on all machines (e.g., on alpha-osf1, long longs are only 64
 the Atari ST, so a Forth written in GNU C can run on all these  bits, the same size as longs (and pointers), but they should be twice as
 machines.  long according to @ref{Long Long, , Double-Word Integers, gcc.info, GNU
   C Manual}). So, we had to implement doubles in C after all. Still, on
   most machines we can use long longs and achieve better performance than
   with the emulation package.}. GNU C is available for free on all
   important (and many 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 machines.
   
 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 3365  lies in the body (which is illegal in th Line 4016  lies in the body (which is illegal in th
 making the code field larger for all words this solution becomes legal  making the code field larger for all words this solution becomes legal
 again. We use this approach for the indirect threaded version. Leaving  again. We use this approach for the indirect threaded version. Leaving
 a cell unused in most words is a bit wasteful, but on the machines we  a cell unused in most words is a bit wasteful, but on the machines we
 are targetting this is hardly a problem. The other reason for having a  are targeting this is hardly a problem. The other reason for having a
 code field size of two cells is to avoid having different image files  code field size of two cells is to avoid having different image files
 for direct and indirect threaded systems (@pxref{System Architecture}).  for direct and indirect threaded systems (@pxref{System Architecture}).
   
Line 3476  An important optimization for stack mach Line 4127  An important optimization for stack mach
 engines, is keeping  one or more of the top stack items in  engines, is keeping  one or more of the top stack items in
 registers.  If a word has the stack effect @var{in1}...@var{inx} @code{--}  registers.  If a word has the stack effect @var{in1}...@var{inx} @code{--}
 @var{out1}...@var{outy}, keeping the top @var{n} items in registers  @var{out1}...@var{outy}, keeping the top @var{n} items in registers
 @itemize  @itemize @bullet
 @item  @item
 is better than keeping @var{n-1} items, if @var{x>=n} and @var{y>=n},  is better than keeping @var{n-1} items, if @var{x>=n} and @var{y>=n},
 due to fewer loads from and stores to the stack.  due to fewer loads from and stores to the stack.
Line 3510  The TOS optimization makes the automatic Line 4161  The TOS optimization makes the automatic
 bit more complicated. Just replacing all occurrences of @code{sp[0]} by  bit more complicated. Just replacing all occurrences of @code{sp[0]} by
 @code{TOS} is not sufficient. There are some special cases to  @code{TOS} is not sufficient. There are some special cases to
 consider:  consider:
 @itemize  @itemize @bullet
 @item In the case of @code{dup ( w -- w w )} the generator must not  @item In the case of @code{dup ( w -- w w )} the generator must not
 eliminate the store to the original location of the item on the stack,  eliminate the store to the original location of the item on the stack,
 if the TOS optimization is turned on.  if the TOS optimization is turned on.
Line 3559  comply to some restrictions: addresses h Line 4210  comply to some restrictions: addresses h
 special words (@code{A!}, @code{A,}, etc.) in order to make the code  special words (@code{A!}, @code{A,}, etc.) in order to make the code
 relocatable. Cells, floats, etc., have to be stored at the natural  relocatable. Cells, floats, etc., have to be stored at the natural
 alignment boundaries@footnote{E.g., store floats (8 bytes) at an address  alignment boundaries@footnote{E.g., store floats (8 bytes) at an address
 dividable by~8. This happens automatically in our system when you use  divisible by~8. This happens automatically in our system when you use
 the ANS Forth alignment words.}, in order to avoid alignment faults on  the ANS Forth alignment words.}, in order to avoid alignment faults on
 machines with stricter alignment. The image file is produced by a  machines with stricter alignment. The image file is produced by a
 metacompiler (@file{cross.fs}).  metacompiler (@file{cross.fs}).
Line 3587  Sieve benchmark on a 486DX2/66 than Gfor Line 4238  Sieve benchmark on a 486DX2/66 than Gfor
   
 However, this potential advantage of assembly language implementations  However, this potential advantage of assembly language implementations
 is not necessarily realized in complete Forth systems: We compared  is not necessarily realized in complete Forth systems: We compared
 Gforth (compiled with @code{gcc-2.6.3} and @code{-DFORCE_REG}) with  Gforth (direct threaded, compiled with @code{gcc-2.6.3} and
 Win32Forth 1.2093 and LMI's NT Forth (Beta, May 1994), two systems  @code{-DFORCE_REG}) with Win32Forth 1.2093, LMI's NT Forth (Beta, May
 written in assembly, and with two systems written in C: PFE-0.9.11  1994) and Eforth (with and without peephole (aka pinhole) optimization
 (compiled with @code{gcc-2.6.3} with the default configuration for  of the threaded code); all these systems were written in assembly
 Linux: @code{-O2 -fomit-frame-pointer -DUSE_REGS}) and ThisForth Beta  language. We also compared Gforth with three systems written in C:
 (compiled with gcc-2.6.3 -O3 -fomit-frame-pointer). We benchmarked  PFE-0.9.14 (compiled with @code{gcc-2.6.3} with the default
 Gforth, PFE and ThisForth on a 486DX2/66 under Linux. Kenneth O'Heskin  configuration for Linux: @code{-O2 -fomit-frame-pointer -DUSE_REGS
 kindly provided the results for Win32Forth and NT Forth on a 486DX2/66  -DUNROLL_NEXT}), ThisForth Beta (compiled with gcc-2.6.3 -O3
 with similar memory performance under Windows NT.  -fomit-frame-pointer; ThisForth employs peephole optimization of the
   threaded code) and TILE (compiled with @code{make opt}). We benchmarked
   Gforth, PFE, ThisForth and TILE 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. Marcel
   Hendrix ported Eforth to Linux, then extended it to run the benchmarks,
   added the peephole optimizer, ran the benchmarks and reported the
   results.
     
 We used four small benchmarks: the ubiquitous Sieve; bubble-sorting and  We used four small benchmarks: the ubiquitous Sieve; bubble-sorting and
 matrix multiplication come from the Stanford integer benchmarks and have  matrix multiplication come from the Stanford integer benchmarks and have
 been translated into Forth by Martin Fraeman; we used the versions  been translated into Forth by Martin Fraeman; we used the versions
 included in the TILE Forth package; and a recursive Fibonacci number  included in the TILE Forth package, but with bigger data set sizes; and
 computation for benchmark calling performance. The following table shows  a recursive Fibonacci number computation for benchmarking calling
 the time taken for the benchmarks scaled by the time taken by Gforth (in  performance. The following table shows the time taken for the benchmarks
 other words, it shows the speedup factor that Gforth achieved over the  scaled by the time taken by Gforth (in other words, it shows the speedup
 other systems).  factor that Gforth achieved over the other systems).
   
 @example  @example
 relative             Win32-        NT               This-  relative      Win32-    NT       eforth       This-
   time     Gforth     Forth     Forth       PFE     Forth    time  Gforth Forth Forth eforth  +opt   PFE Forth  TILE
 sieve        1.00      1.30      1.07      1.67      2.98  sieve     1.00  1.39  1.14   1.39  0.85  1.58  3.18  8.58
 bubble       1.00      1.30      1.40      1.66  bubble    1.00  1.31  1.41   1.48  0.88  1.50        3.88
 matmul       1.00      1.40      1.29      2.24  matmul    1.00  1.47  1.35   1.46  0.74  1.58        4.09
 fib          1.00      1.44      1.26      1.82      2.82  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 3624  method for relocating the Forth image: l Line 4282  method for relocating the Forth image: l
 the actual addresses at run time, resulting in two address computations  the actual addresses at run time, resulting in two address computations
 per NEXT (@pxref{System Architecture}).  per NEXT (@pxref{System Architecture}).
   
 The speedup of Gforth over PFE and ThisForth can be easily explained  Only Eforth with the peephole optimizer performs comparable to
 with the self-imposed restriction to standard C (although the measured  Gforth. The speedups achieved with peephole optimization of threaded
 implementation of PFE uses a GNU C extension: global register  code are quite remarkable. Adding a peephole optimizer to Gforth should
 variables), which makes efficient threading impossible.  Moreover,  cause similar speedups.
 current C compilers have a hard time optimizing other aspects of the  
 ThisForth source.  The speedup of Gforth over PFE, ThisForth and TILE can be easily
   explained with the self-imposed restriction to standard C, which makes
   efficient threading impossible (however, the measured implementation of
   PFE uses a GNU C extension: @ref{Global Reg Vars, , Defining Global
   Register Variables, gcc.info, GNU C Manual}).  Moreover, current C
   compilers have a hard time optimizing other aspects of the ThisForth
   and the TILE source.
   
 Note that the performance of Gforth on 386 architecture processors  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}  varies widely with the version of @code{gcc} used. E.g., @code{gcc-2.5.8}
Line 3638  machine registers by itself and would no Line 4302  machine registers by itself and would no
 register declarations, giving a 1.3 times slower engine (on a 486DX2/66  register declarations, giving a 1.3 times slower engine (on a 486DX2/66
 running the Sieve) than the one measured above.  running the Sieve) than the one measured above.
   
 @node Bugs, Pedigree, Internals, Top  In @cite{Translating Forth to Efficient C} by M. Anton Ertl and Martin
   Maierhofer (presented at EuroForth '95), an indirect threaded version of
   Gforth is compared with Win32Forth, NT Forth, PFE, and ThisForth; that
   version of Gforth is 2\%@minus{}8\% slower on a 486 than the version
   used here. The paper available at
   @*@file{http://www.complang.tuwien.ac.at/papers/ertl&maierhofer95.ps.gz};
   it also contains numbers for some native code systems. You can find
   numbers for Gforth on various machines in @file{Benchres}.
   
   @node Bugs, Origin, Internals, Top
 @chapter Bugs  @chapter Bugs
   
 Known bugs are described in the file BUGS in the Gforth distribution.  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  If you find a bug, please send a bug report to
   @code{bug-gforth@@gnu.ai.mit.edu}. A bug report should
 describe the Gforth version used (it is announced at the start of an  describe the Gforth version used (it is announced at the start of an
 interactive Gforth session), the machine and operating system (on Unix  interactive Gforth session), the machine and operating system (on Unix
 systems you can use @code{uname -a} to produce this information), the  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  installation options (send the @code{config.status} file), and a
 changes you (or your installer) have made to the Gforth sources (if  complete list of changes you (or your installer) have made to the Gforth
 any); it should contain a program (or a sequence of keyboard commands)  sources (if any); it should contain a program (or a sequence of keyboard
 that reproduces the bug and a description of what you think constitutes  commands) that reproduces the bug and a description of what you think
 the buggy behaviour.  constitutes the buggy behaviour.
   
 For a thorough guide on reporting bugs read @ref{Bug Reporting, , How  For a thorough guide on reporting bugs read @ref{Bug Reporting, , How
 to Report Bugs, gcc.info, GNU C Manual}.  to Report Bugs, gcc.info, GNU C Manual}.
   
   
 @node Pedigree, Word Index, Bugs, Top  @node Origin, Word Index, Bugs, Top
 @chapter Pedigree  @chapter Authors and Ancestors of Gforth
   
 Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by  @section Authors and Contributors
 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.  The Gforth project was started in mid-1992 by Bernd Paysan and Anton
   Ertl. The third major author was Jens Wilke.  Lennart Benschop (who was
   one of Gforth's first users, in mid-1993) and Stuart Ramsden inspired us
   with their continuous feedback. Lennart Benshop contributed
   @file{glosgen.fs}, while Stuart Ramsden has been working on automatic
   support for calling C libraries. Helpful comments also came from Paul
   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,
   and autoconf, among others), and to the creators of the Internet: Gforth
   was developed across the Internet, and its authors have not met
   physically yet.
   
   @section 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.
   
 VolksForth descends from F83. !! Authors? When?  Bernd Paysan wrote BigForth, a descendent from TurboForth, an unreleased
   32 bit native code version of VolksForth for the Atari ST, written
   mostly by Dietrich Weineck.
   
   VolksForth descends from F83. It was written by Klaus Schleisiek, Bernd
   Pennemann, Georg Rehfeld and Dietrich Weineck for the C64 (called
   UltraForth there) in the mid-80s and ported to the Atari ST in 1986.
   
 Laxen and Perry wrote F83 as a model implementation of the  Henry Laxen and Mike Perry wrote F83 as a model implementation of the
 Forth-83 standard. !! Pedigree? When?  Forth-83 standard. !! Pedigree? When?
   
 A team led by Bill Ragsdale implemented fig-Forth on many processors in  A team led by Bill Ragsdale implemented fig-Forth on many processors in
 1979. Dean Sanderson and Bill Ragsdale developed the original  1979. Robert Selzer and Bill Ragsdale developed the original
 implementation of fig-Forth based on microForth.  implementation of fig-Forth for the 6502 based on microForth.
   
 !! microForth pedigree  The principal architect of microForth was Dean Sanderson. microForth was
   FORTH, Inc.'s first off-the-shelf product. It was developed in 1976 for
   the 1802, and subsequently implemented on the 8080, the 6800 and the
   Z80.
   
   All earlier Forth systems were custom-made, usually by Charles Moore,
   who discovered (as he puts it) Forth during the late 60s. The first full
   Forth existed in 1971.
   
 A part of the information in this section comes from @cite{The Evolution  A part of the information in this section comes from @cite{The Evolution
 of Forth} by Elizabeth D. Rather, Donald R. Colburn and Charles  of Forth} by Elizabeth D. Rather, Donald R. Colburn and Charles
Line 3682  H. Moore, presented at the HOPL-II confe Line 4386  H. Moore, presented at the HOPL-II confe
 Notices 28(3), 1993.  You can find more historical and genealogical  Notices 28(3), 1993.  You can find more historical and genealogical
 information about Forth there.  information about Forth there.
   
 @node Word Index, Node Index, Pedigree, Top  @node Word Index, Node Index, Origin, Top
 @chapter Word Index  @chapter Word Index
   
 This index is as incomplete as the manual. Each word is listed with  This index is as incomplete as the manual. Each word is listed with

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