version 1.27, 1995/12/04 16:38:53
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version 1.32, 1996/02/19 18:57:26
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@comment %**end of header (This is for running Texinfo on a region.) |
@comment %**end of header (This is for running Texinfo on a region.) |
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@ifinfo |
@ifinfo |
This file documents Gforth 0.1 |
This file documents Gforth 0.2 |
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Copyright @copyright{} 1995 Free Software Foundation, Inc. |
Copyright @copyright{} 1995,1996 Free Software Foundation, Inc. |
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Permission is granted to make and distribute verbatim copies of |
Permission is granted to make and distribute verbatim copies of |
this manual provided the copyright notice and this permission notice |
this manual provided the copyright notice and this permission notice |
Line 41 Copyright @copyright{} 1995 Free Softwar
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Line 41 Copyright @copyright{} 1995 Free Softwar
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@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 |
@center Bernd Paysan |
Line 51 Copyright @copyright{} 1995 Free Softwar
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Line 51 Copyright @copyright{} 1995 Free Softwar
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@comment The following two commands start the copyright page. |
@comment The following two commands start the copyright page. |
@page |
@page |
@vskip 0pt plus 1filll |
@vskip 0pt plus 1filll |
Copyright @copyright{} 1995 Free Software Foundation, Inc. |
Copyright @copyright{} 1995,1996 Free Software Foundation, Inc. |
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@comment !! Published by ... or You can get a copy of this manual ... |
@comment !! Published by ... or You can get a copy of this manual ... |
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Line 77 Copyright @copyright{} 1995 Free Softwar
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Line 77 Copyright @copyright{} 1995 Free Softwar
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@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 |
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@menu |
@menu |
Line 91 personal machines. This manual correspon
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Line 91 personal machines. This manual correspon
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* 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 1141 system that only supplies @code{THEN} is
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Line 1141 system that only supplies @code{THEN} is
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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.] |
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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 |
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efficient than using @code{?dup}. Definitions in plain standard Forth |
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for @code{ENDIF}, @code{?DUP-IF} and @code{?DUP-0=-IF} are provided in |
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@file{compat/control.fs}. |
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@example |
@example |
@var{n} |
@var{n} |
Line 1234 arithmetic). This behaviour is usually n
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Line 1237 arithmetic). This behaviour is usually n
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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 |
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port; e.g.: |
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@example |
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: +DO ( compile-time: -- do-sys; run-time: n1 n2 -- ) |
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POSTPONE over POSTPONE min POSTPONE ?DO ; immediate |
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@end example |
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@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 1268 between @var{limit+1} and @var{limit} is
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Line 1265 between @var{limit+1} and @var{limit} is
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@code{ 0 0 -DO i . 1 -LOOP} prints nothing |
@code{ 0 0 -DO i . 1 -LOOP} prints nothing |
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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 |
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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}. |
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The loop is terminated when the border between @var{limit@minus{}sgn(n)} |
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and @var{limit} is crossed. Unfortunately, neither @code{-LOOP} nor |
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@code{S+LOOP} are part of the ANS Forth standard, and they are not easy |
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to implement using standard words. If you want to write standard |
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programs, just avoid counting down. |
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@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 1300 This is the preferred loop of native cod
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Line 1291 This is the preferred loop of native cod
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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} |
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loops. |
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@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 1336 doc-else
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Line 1328 doc-else
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doc-while |
doc-while |
doc-repeat |
doc-repeat |
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Gforth adds some more control-structure words: |
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doc-endif |
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doc-?dup-if |
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doc-?dup-0=-if |
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Counted loop words constitute a separate group of words: |
Counted loop words constitute a separate group of words: |
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doc-?do |
doc-?do |
Line 1346 doc-u-do
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Line 1344 doc-u-do
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doc-do |
doc-do |
doc-for |
doc-for |
doc-loop |
doc-loop |
doc-s+loop |
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doc-+loop |
doc-+loop |
doc--loop |
doc--loop |
doc-next |
doc-next |
Line 1411 while
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Line 1408 while
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repeat |
repeat |
@end example |
@end example |
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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. |
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Line 1736 E.g., a definition using @code{TO} might
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Line 1733 E.g., a definition using @code{TO} might
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: strcmp @{ addr1 u1 addr2 u2 -- n @} |
: strcmp @{ addr1 u1 addr2 u2 -- n @} |
u1 u2 min 0 |
u1 u2 min 0 |
?do |
?do |
addr1 c@ addr2 c@ - ?dup |
addr1 c@ addr2 c@ - |
if |
?dup-if |
unloop exit |
unloop exit |
then |
then |
addr1 char+ TO addr1 |
addr1 char+ TO addr1 |
Line 1759 are initialized with the right value for
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Line 1756 are initialized with the right value for
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addr1 addr2 |
addr1 addr2 |
u1 u2 min 0 |
u1 u2 min 0 |
?do @{ s1 s2 @} |
?do @{ s1 s2 @} |
s1 c@ s2 c@ - ?dup |
s1 c@ s2 c@ - |
if |
?dup-if |
unloop exit |
unloop exit |
then |
then |
s1 char+ s2 char+ |
s1 char+ s2 char+ |
Line 1939 name produces their value. Their value c
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Line 1936 name produces their value. Their value c
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Since this syntax is supported by Gforth directly, you need not do |
Since this syntax is supported by Gforth directly, you need not do |
anything to use it. If you want to port a program using this syntax to |
anything to use it. If you want to port a program using this syntax to |
another ANS Forth system, use @file{anslocal.fs} to implement the syntax |
another ANS Forth system, use @file{compat/anslocal.fs} to implement the |
on the other system. |
syntax on the other system. |
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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 3243 Also, if you @code{include} @file{etags.
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Line 3240 Also, if you @code{include} @file{etags.
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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 |
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Table,emacs, Emacs Manual}). The TAGS file for the preloaded words is |
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@file{$(datadir)/gforth/$(VERSION)/TAGS} (e.g., |
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@file{/usr/local/share/gforth/0.2/TAGS}). |
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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 3299 GNU C Manual}). Its labels as values fea
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Line 3299 GNU C Manual}). Its labels as values fea
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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 Forths |
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 |
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C Manual}). So, we had to implement doubles in C after all. Still, on |
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most machines we can use long longs and achieve better performance than |
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with the emulation package.}. GNU C is available for free on all |
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important (and many unimportant) UNIX machines, VMS, 80386s running |
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MS-DOS, the Amiga, and the Atari ST, so a Forth written in GNU C can run |
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on all these machines. |
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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 3656 Gforth (direct threaded, compiled with @
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Line 3662 Gforth (direct threaded, compiled with @
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@code{-DFORCE_REG}) with Win32Forth 1.2093, LMI's NT Forth (Beta, May |
@code{-DFORCE_REG}) with Win32Forth 1.2093, LMI's NT Forth (Beta, May |
1994) and Eforth (with and without peephole (aka pinhole) optimization |
1994) and Eforth (with and without peephole (aka pinhole) optimization |
of the threaded code); all these systems were written in assembly |
of the threaded code); all these systems were written in assembly |
language. We also compared Gforth with two systems written in C: |
language. We also compared Gforth with three systems written in C: |
PFE-0.9.11 (compiled with @code{gcc-2.6.3} with the default |
PFE-0.9.14 (compiled with @code{gcc-2.6.3} with the default |
configuration for Linux: @code{-O2 -fomit-frame-pointer -DUSE_REGS}) and |
configuration for Linux: @code{-O2 -fomit-frame-pointer -DUSE_REGS |
ThisForth Beta (compiled with gcc-2.6.3 -O3 -fomit-frame-pointer; |
-DUNROLL_NEXT}), ThisForth Beta (compiled with gcc-2.6.3 -O3 |
ThisForth employs peephole optimization of the threaded code). We |
-fomit-frame-pointer; ThisForth employs peephole optimization of the |
benchmarked Gforth, PFE and ThisForth on a 486DX2/66 under |
threaded code) and TILE (compiled with @code{make opt}). We benchmarked |
Linux. Kenneth O'Heskin kindly provided the results for Win32Forth and |
Gforth, PFE, ThisForth and TILE on a 486DX2/66 under Linux. Kenneth |
NT Forth on a 486DX2/66 with similar memory performance under Windows |
O'Heskin kindly provided the results for Win32Forth and NT Forth on a |
NT. Marcel Hendrix ported Eforth to Linux, then extended it to run the |
486DX2/66 with similar memory performance under Windows NT. Marcel |
benchmarks, added the peephole optimizer, ran the benchmarks and |
Hendrix ported Eforth to Linux, then extended it to run the benchmarks, |
reported the results. |
added the peephole optimizer, ran the benchmarks and reported the |
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results. |
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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 benchmarking 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). |
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@example |
@example |
relative Win32- NT eforth This- |
relative Win32- NT eforth This- |
time Gforth Forth Forth eforth +opt PFE Forth |
time Gforth Forth Forth eforth +opt PFE Forth TILE |
sieve 1.00 1.39 1.14 1.39 0.85 1.78 3.18 |
sieve 1.00 1.39 1.14 1.39 0.85 1.58 3.18 8.58 |
bubble 1.00 1.33 1.43 1.51 0.89 1.70 |
bubble 1.00 1.31 1.41 1.48 0.88 1.50 3.88 |
matmul 1.00 1.43 1.31 1.42 1.12 2.28 |
matmul 1.00 1.47 1.35 1.46 1.16 1.58 4.09 |
fib 1.00 1.55 1.36 1.24 1.15 1.97 3.04 |
fib 1.00 1.52 1.34 1.22 1.13 1.74 2.99 4.30 |
@end example |
@end example |
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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 3700 Gforth. The speedups achieved with peeph
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Line 3707 Gforth. The speedups achieved with peeph
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code are quite remarkable. Adding a peephole optimizer to Gforth should |
code are quite remarkable. Adding a peephole optimizer to Gforth should |
cause similar speedups. |
cause similar speedups. |
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The speedup of Gforth over PFE and ThisForth can be easily explained |
The speedup of Gforth over PFE, ThisForth and TILE can be easily |
with the self-imposed restriction to standard C (although the measured |
explained with the self-imposed restriction to standard C, which makes |
implementation of PFE uses a GNU C extension: global register |
efficient threading impossible (however, the measured implementation of |
variables), which makes efficient threading impossible. Moreover, |
PFE uses a GNU C extension: @ref{Global Reg Vars, , Defining Global |
current C compilers have a hard time optimizing other aspects of the |
Register Variables, gcc.info, GNU C Manual}). Moreover, current C |
ThisForth source. |
compilers have a hard time optimizing other aspects of the ThisForth |
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and the TILE source. |
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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 3723 used here. The paper available at
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Line 3731 used here. The paper available at
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it also contains numbers for some native code systems. You can find |
it also contains numbers for some native code systems. You can find |
numbers for Gforth on various machines in @file{Benchres}. |
numbers for Gforth on various machines in @file{Benchres}. |
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@node Bugs, Pedigree, Internals, Top |
@node Bugs, Origin, Internals, Top |
@chapter Bugs |
@chapter Bugs |
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Known bugs are described in the file BUGS in the Gforth distribution. |
Known bugs are described in the file BUGS in the Gforth distribution. |
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If you find a bug, please send a bug report to |
If you find a bug, please send a bug report to |
@code{gforth-bugs@@mips.complang.tuwien.ac.at}. A bug report should |
@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 |
Line 3743 For a thorough guide on reporting bugs r
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Line 3751 For a thorough guide on reporting bugs r
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to Report Bugs, gcc.info, GNU C Manual}. |
to Report Bugs, gcc.info, GNU C Manual}. |
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@node Pedigree, Word Index, Bugs, Top |
@node Origin, Word Index, Bugs, Top |
@chapter Pedigree |
@chapter Authors and Ancestors of Gforth |
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@section Authors and Contributors |
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The Gforth project was started in mid-1992 by Bernd Paysan and Anton |
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Ertl. The third major author was Jens Wilke. Lennart Benschop (who was |
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one of Gforth's first users, in mid-1993) and Stuart Ramsden inspired us |
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with their continuous feedback. Lennart Benshop contributed |
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@file{glosgen.fs}, while Stuart Ramsden has been working on automatic |
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support for calling C libraries. Helpful comments also came from Paul |
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Kleinrubatscher, Christian Pirker, Dirk Zoller and Marcel Hendrix. |
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Gforth also owes a lot to the authors of the tools we used (GCC, CVS, |
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and autoconf, among others), and to the creators of the Internet: Gforth |
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was developed across the Internet, and its authors have not met |
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physically yet. |
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@section Pedigree |
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Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by |
Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by |
Dirk Zoller) will cross-fertilize each other. Of course, a significant |
Dirk Zoller) will cross-fertilize each other. Of course, a significant |
Line 3771 the 1802, and subsequently implemented o
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Line 3796 the 1802, and subsequently implemented o
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Z80. |
Z80. |
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All earlier Forth systems were custom-made, usually by Charles Moore, |
All earlier Forth systems were custom-made, usually by Charles Moore, |
who discovered (as he puts it) Forth in the late 60s. |
who discovered (as he puts it) Forth during the late 60s. The first full |
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Forth existed in 1971. |
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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 3779 H. Moore, presented at the HOPL-II confe
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Line 3805 H. Moore, presented at the HOPL-II confe
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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. |
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@node Word Index, Node Index, Pedigree, Top |
@node Word Index, Node Index, Origin, Top |
@chapter Word Index |
@chapter Word Index |
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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 |