--- gforth/Attic/gforth.ds 1995/11/07 18:06:41 1.21 +++ gforth/Attic/gforth.ds 1996/01/07 17:22:09 1.29 @@ -36,6 +36,7 @@ Copyright @copyright{} 1995 Free Softwar of in the original English. @end ifinfo +@finalout @titlepage @sp 10 @center @titlefont{Gforth Manual} @@ -43,6 +44,7 @@ Copyright @copyright{} 1995 Free Softwar @center for version 0.1 @sp 2 @center Anton Ertl +@center Bernd Paysan @sp 3 @center This manual is under construction @@ -89,7 +91,7 @@ personal machines. This manual correspon * Emacs and Gforth:: The Gforth Mode * Internals:: Implementation details * Bugs:: How to report them -* Pedigree:: Ancestors of Gforth +* Origin:: Authors and ancestors of Gforth * Word Index:: An item for each Forth word * Node Index:: An item for each node @end menu @@ -487,7 +489,10 @@ library. If this is what you want to do Public License instead of this License. @iftex +@node Preface +@comment node-name, next, previous, up @unnumbered Preface +@cindex Preface This manual documents Gforth. The reader is expected to know Forth. This manual is primarily a reference manual. @xref{Other Books} for introductory material. @@ -555,7 +560,7 @@ can also get it from Global Engineering for publication is available electronically and for free in some MS Word format, and it has been converted to HTML. Some pointers to these 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 introductory book based on a draft version of the standard. It does not @@ -642,6 +647,12 @@ Forth words, you have to quote them or u after processing the command line (instead of entering interactive mode) 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: On startup the system first executes the system initialization file (unless the option @code{--no-init-file} is given; note that the system @@ -1434,6 +1445,11 @@ laden with restrictions. Therefore, we p locals wordset, but also our own, more powerful locals wordset (we 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 * Gforth locals:: * ANS Forth locals:: @@ -2073,9 +2089,9 @@ machine code), and for defining the the nature of Gforth poses a few problems: First of all. Gforth runs on several architectures, so it can provide no standard assembler. What's 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 Gforth. If you do not have an assembler, you can compile machine code directly with @code{,} and @code{c,}. @@ -2093,10 +2109,42 @@ These words are rarely used. Therefore t which is usually not loaded (except @code{flush-icache}, which is always 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 is: adding the wanted functionality to the source of Gforth. For normal words you just have to edit @file{primitives}, defining words (for fast -defined words) probably require changes in @file{engine.c}, +defined words) may require changes in @file{engine.c}, @file{kernal.fs}, @file{prims2x.fs}, and possibly @file{cross.fs}. @@ -2369,7 +2417,7 @@ characters is determined by the locale y @item division rounding: 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{/}). @item values of @code{STATE} when true: @@ -2480,9 +2528,14 @@ The next invocation of a parsing word re 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}: -!!???If the argument input source is a valid input source then it gets -restored. Otherwise causes @code{-12 THROW}, which, unless caught, issues -the message "argument type mismatch" and aborts. +@code{-12 THROW}. Note that, once an input file is closed (e.g., because +the end of the file was reached), its source-id may be +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 retore input source specifications +from other than the current input soruce. @item data space containing definitions gets de-allocated: Deallocation with @code{allot} is not checked. This typically resuls in @@ -2554,14 +2607,17 @@ Not checked. As usual, you can expect me None. @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: @code{sp@ here - .} gives the space remaining for dictionary and data stack together. @item return stack space available: -!!?? +By default 16 KBytes. The default can be overridden with the @code{-r} +switch (@pxref{Invocation}) when Gforth starts up. @item stack space available: @code{sp@ here - .} gives the space remaining for dictionary and data @@ -2882,7 +2938,10 @@ System dependent; @code{REPRESENT} is im function @code{ecvt()} and inherits its behaviour in this respect. @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: @code{s" FLOATING-STACK" environment? drop .}. Can be changed at startup @@ -3184,7 +3243,10 @@ Also, if you @code{include} @file{etags. 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 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/TAGS}). To get all these benefits, add the following lines to your @file{.emacs} file: @@ -3200,6 +3262,12 @@ file: Reading this section is not necessary for programming with Gforth. It 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 * Portability:: * Threading:: @@ -3587,32 +3655,38 @@ Sieve benchmark on a 486DX2/66 than Gfor However, this potential advantage of assembly language implementations is not necessarily realized in complete Forth systems: We compared -Gforth (compiled with @code{gcc-2.6.3} and @code{-DFORCE_REG}) with -Win32Forth 1.2093 and LMI's NT Forth (Beta, May 1994), two systems -written in assembly, and with two systems written in C: PFE-0.9.11 -(compiled with @code{gcc-2.6.3} with the default configuration for -Linux: @code{-O2 -fomit-frame-pointer -DUSE_REGS}) and ThisForth Beta -(compiled with gcc-2.6.3 -O3 -fomit-frame-pointer). We benchmarked -Gforth, PFE and ThisForth on a 486DX2/66 under Linux. Kenneth O'Heskin -kindly provided the results for Win32Forth and NT Forth on a 486DX2/66 -with similar memory performance under Windows NT. +Gforth (direct threaded, compiled with @code{gcc-2.6.3} and +@code{-DFORCE_REG}) with Win32Forth 1.2093, LMI's NT Forth (Beta, May +1994) and Eforth (with and without peephole (aka pinhole) optimization +of the threaded code); all these systems were written in assembly +language. We also compared Gforth with two systems written in C: +PFE-0.9.11 (compiled with @code{gcc-2.6.3} with the default +configuration for Linux: @code{-O2 -fomit-frame-pointer -DUSE_REGS}) and +ThisForth Beta (compiled with gcc-2.6.3 -O3 -fomit-frame-pointer; +ThisForth employs peephole optimization of the threaded code). We +benchmarked Gforth, PFE and ThisForth on a 486DX2/66 under +Linux. Kenneth O'Heskin kindly provided the results for Win32Forth and +NT Forth on a 486DX2/66 with similar memory performance under Windows +NT. 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 matrix multiplication come from the Stanford integer benchmarks and have been translated into Forth by Martin Fraeman; we used the versions included in the TILE Forth package; and a recursive Fibonacci number -computation for benchmark calling performance. The following table shows +computation for benchmarking calling performance. The following table shows the time taken for the benchmarks scaled by the time taken by Gforth (in other words, it shows the speedup factor that Gforth achieved over the other systems). @example -relative Win32- NT This- - time Gforth Forth Forth PFE Forth -sieve 1.00 1.30 1.07 1.67 2.98 -bubble 1.00 1.30 1.40 1.66 -matmul 1.00 1.40 1.29 2.24 -fib 1.00 1.44 1.26 1.82 2.82 +relative Win32- NT eforth This- +time Gforth Forth Forth eforth +opt PFE Forth +sieve 1.00 1.39 1.14 1.39 0.85 1.78 3.18 +bubble 1.00 1.33 1.43 1.51 0.89 1.70 +matmul 1.00 1.43 1.31 1.42 1.12 2.28 +fib 1.00 1.55 1.36 1.24 1.15 1.97 3.04 @end example You may find the good performance of Gforth compared with the systems @@ -3624,6 +3698,11 @@ method for relocating the Forth image: l the actual addresses at run time, resulting in two address computations per NEXT (@pxref{System Architecture}). +Only Eforth with the peephole optimizer performs comparable to +Gforth. The speedups achieved with peephole optimization of threaded +code are quite remarkable. Adding a peephole optimizer to Gforth should +cause similar speedups. + The speedup of Gforth over PFE and ThisForth can be easily explained with the self-imposed restriction to standard C (although the measured implementation of PFE uses a GNU C extension: global register @@ -3638,43 +3717,76 @@ machine registers by itself and would no register declarations, giving a 1.3 times slower engine (on a 486DX2/66 running the Sieve) than the one measured above. -@node Bugs, Pedigree, Internals, Top +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 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{gforth-bugs@@mips.complang.tuwien.ac.at}. A bug report should describe the Gforth version used (it is announced at the start of an interactive Gforth session), the machine and operating system (on Unix systems you can use @code{uname -a} to produce this information), the -installation options (!! a way to find them out), and a complete list of -changes you (or your installer) have made to the Gforth sources (if -any); it should contain a program (or a sequence of keyboard commands) -that reproduces the bug and a description of what you think constitutes -the buggy behaviour. +installation options (send the @code{config.status} file), and a +complete list of changes you (or your installer) have made to the Gforth +sources (if any); it should contain a program (or a sequence of keyboard +commands) that reproduces the bug and a description of what you think +constitutes the buggy behaviour. For a thorough guide on reporting bugs read @ref{Bug Reporting, , How to Report Bugs, gcc.info, GNU C Manual}. -@node Pedigree, Word Index, Bugs, Top -@chapter Pedigree +@node Origin, Word Index, Bugs, Top +@chapter Authors and Ancestors of Gforth -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. +@section Authors and Contributors + +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 +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 and Marcel Hendrix. -Bernd Paysan wrote BigForth, a child of VolksForth. +@section Pedigree -VolksForth descends from F83. !! Authors? When? +Gforth descends from BigForth (1993) and fig-Forth. Gforth and PFE (by +Dirk Zoller) will cross-fertilize each other. Of course, a significant +part of the design of Gforth was prescribed by ANS Forth. + +Bernd Paysan wrote BigForth, a 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 +Hennry Laxen and Mike Perry wrote F83 as a model implementation of the Forth-83 standard. !! Pedigree? When? A team led by Bill Ragsdale implemented fig-Forth on many processors in -1979. Dean Sanderson and Bill Ragsdale developed the original -implementation of fig-Forth based on microForth. +1979. Robert Selzer and Bill Ragsdale developed the original +implementation of fig-Forth for the 6502 based on microForth. + +The principal architect of microForth was Dean Sanderson. microForth was +FORTH, Inc.'s first off-the-shelf product. It was developped in 1976 for +the 1802, and subsequently implemented on the 8080, the 6800 and the +Z80. -!! microForth pedigree +All earlier Forth systems were custom-made, usually by Charles Moore, +who discovered (as he puts it) Forth in the late 60s. A part of the information in this section comes from @cite{The Evolution of Forth} by Elizabeth D. Rather, Donald R. Colburn and Charles @@ -3682,7 +3794,7 @@ H. Moore, presented at the HOPL-II confe Notices 28(3), 1993. You can find more historical and genealogical information about Forth there. -@node Word Index, Node Index, Pedigree, Top +@node Word Index, Node Index, Origin, Top @chapter Word Index This index is as incomplete as the manual. Each word is listed with