version 1.29, 1996/01/07 17:22:09
|
version 1.30, 1996/01/25 16:45:50
|
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 Free Software Foundation, Inc. |
|
|
Line 41 Copyright @copyright{} 1995 Free Softwar
|
Line 41 Copyright @copyright{} 1995 Free Softwar
|
@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 77 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 1234 arithmetic). This behaviour is usually n
|
Line 1234 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 1268 between @var{limit+1} and @var{limit} is
|
Line 1262 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 1300 This is the preferred loop of native cod
|
Line 1288 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 1346 doc-u-do
|
Line 1335 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 1411 while
|
Line 1399 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 1939 name produces their value. Their value c
|
Line 1927 name produces their value. Their value c
|
|
|
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 3659 Gforth (direct threaded, compiled with @
|
Line 3647 Gforth (direct threaded, compiled with @
|
@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-0.9.11 (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; |
ThisForth Beta (compiled with gcc-2.6.3 -O3 -fomit-frame-pointer; |
ThisForth employs peephole optimization of the threaded code). We |
ThisForth employs peephole optimization of the threaded code) and TILE |
benchmarked Gforth, PFE and ThisForth on a 486DX2/66 under |
(compiled with @code{make opt}). We benchmarked Gforth, PFE, ThisForth |
Linux. Kenneth O'Heskin kindly provided the results for Win32Forth and |
and TILE on a 486DX2/66 under Linux. Kenneth O'Heskin kindly provided |
NT Forth on a 486DX2/66 with similar memory performance under Windows |
the results for Win32Forth and NT Forth on a 486DX2/66 with similar |
NT. Marcel Hendrix ported Eforth to Linux, then extended it to run the |
memory performance under Windows NT. Marcel Hendrix ported Eforth to |
benchmarks, added the peephole optimizer, ran the benchmarks and |
Linux, then extended it to run the benchmarks, added the peephole |
reported the results. |
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 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). |
|
|
@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 1.78 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 1.67 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 2.36 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 1.93 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 3703 Gforth. The speedups achieved with peeph
|
Line 3691 Gforth. The speedups achieved with peeph
|
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. |
|
|
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 |
|
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 3752 to Report Bugs, gcc.info, GNU C Manual}.
|
Line 3741 to Report Bugs, gcc.info, GNU C Manual}.
|
@section Authors and Contributors |
@section Authors and Contributors |
|
|
The Gforth project was started in mid-1992 by Bernd Paysan and Anton |
The Gforth project was started in mid-1992 by Bernd Paysan and Anton |
Ertl. The third major author was Jens Wilke. Lennart Benschop (who also |
Ertl. The third major author was Jens Wilke. Lennart Benschop (who was |
was one of Gforth's first users, in mid-1993) and Stuart Ramsden |
one of Gforth's first users, in mid-1993) and Stuart Ramsden inspired us |
inspired us with their continuous feedback. Lennart Benshop contributed |
with their continuous feedback. Lennart Benshop contributed |
@file{glosgen.fs}, while Stuart Ramsden has been working on automatic |
@file{glosgen.fs}, while Stuart Ramsden has been working on automatic |
support for calling C libraries. Helpful comments also came from Paul |
support for calling C libraries. Helpful comments also came from Paul |
Kleinrubatscher, Christian Pirker, Dirk Zoller and Marcel Hendrix. |
Kleinrubatscher, Christian Pirker, Dirk Zoller and Marcel Hendrix. |
|
|
|
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 |
@section Pedigree |
|
|
Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by |
Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by |
Line 3786 the 1802, and subsequently implemented o
|
Line 3780 the 1802, and subsequently implemented o
|
Z80. |
Z80. |
|
|
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 |
|
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 |