From 194e3f36f539ff90540bfb780cfbd424d7f6aaec Mon Sep 17 00:00:00 2001 From: rich Date: Wed, 26 Sep 2007 22:47:49 +0000 Subject: [PATCH] Just comment updates --- jonesforth.S | 44 +++++++++++++++++++++++++++----------------- 1 file changed, 27 insertions(+), 17 deletions(-) diff --git a/jonesforth.S b/jonesforth.S index 3409cb8..681f9a8 100644 --- a/jonesforth.S +++ b/jonesforth.S @@ -1,7 +1,7 @@ /* A sometimes minimal FORTH compiler and tutorial for Linux / i386 systems. -*- asm -*- By Richard W.M. Jones http://annexia.org/forth This is PUBLIC DOMAIN (see public domain release statement below). - $Id: jonesforth.S,v 1.32 2007-09-26 22:20:52 rich Exp $ + $Id: jonesforth.S,v 1.33 2007-09-26 22:47:49 rich Exp $ gcc -m32 -nostdlib -static -Wl,-Ttext,0 -o jonesforth jonesforth.S */ @@ -45,7 +45,8 @@ over every other element in a list of numbers? You can add it to the language. What about an operator which pulls in variables directly from a configuration file and makes them available as FORTH variables? Or how about adding Makefile-like dependencies to - the language? No problem in FORTH. This concept isn't common in programming languages, + the language? No problem in FORTH. How about modifying the FORTH compiler to allow + complex inlining strategies -- simple. This concept isn't common in programming languages, but it has a name (in fact two names): "macros" (by which I mean LISP-style macros, not the lame C preprocessor) and "domain specific languages" (DSLs). @@ -74,8 +75,14 @@ This code draws heavily on the design of LINA FORTH (http://home.hccnet.nl/a.w.m.van.der.horst/lina.html) by Albert van der Horst. Any similarities in the code are probably not accidental. - Also I used this document (http://ftp.funet.fi/pub/doc/IOCCC/1992/buzzard.2.design) which really - defies easy explanation. + Some parts of this FORTH are also based on this IOCCC entry from 1992: + http://ftp.funet.fi/pub/doc/IOCCC/1992/buzzard.2.design. + I was very proud when Sean Barrett, the original author of the IOCCC entry, commented in the LtU thread + http://lambda-the-ultimate.org/node/2452#comment-36818 about this FORTH. + + And finally I'd like to acknowledge the (possibly forgotten?) authors of ARTIC FORTH because their + original program which I still have on original cassette tape kept nagging away at me all these years. + http://en.wikipedia.org/wiki/Artic_Software PUBLIC DOMAIN ---------------------------------------------------------------------- @@ -600,7 +607,7 @@ bufftop: /* BUILT-IN WORDS ---------------------------------------------------------------------- - Remember our dictionary entries (headers). Let's bring those together with the codeword + Remember our dictionary entries (headers)? Let's bring those together with the codeword and data words to see how : DOUBLE DUP + ; really looks in memory. pointer to previous word @@ -784,8 +791,8 @@ code_\label : // assembler code follows NEXT /* - In this FORTH, only /MOD is primitive. We define the / and MOD words in - terms of /MOD. + In this FORTH, only /MOD is primitive. Later we will define the / and MOD words in + terms of the primitive /MOD. */ defcode "/MOD",4,,DIVMOD @@ -875,7 +882,7 @@ code_\label : // assembler code follows 1: pushl $1 NEXT - defcode "0<",2,,ZLT + defcode "0<",2,,ZLT // comparisons with 0 pop %eax test %eax,%eax jl 1f @@ -911,22 +918,22 @@ code_\label : // assembler code follows 1: pushl $1 NEXT - defcode "AND",3,,AND + defcode "AND",3,,AND // bitwise AND pop %eax andl %eax,(%esp) NEXT - defcode "OR",2,,OR + defcode "OR",2,,OR // bitwise OR pop %eax orl %eax,(%esp) NEXT - defcode "XOR",3,,XOR + defcode "XOR",3,,XOR // bitwise XOR pop %eax xorl %eax,(%esp) NEXT - defcode "INVERT",6,,INVERT // this is the FORTH bitwise "NOT" function + defcode "INVERT",6,,INVERT // this is the FORTH bitwise "NOT" function (cf. NEGATE) notl (%esp) NEXT @@ -975,7 +982,7 @@ code_\label : // assembler code follows | addr of EXIT | +------------------+ - And NEXT just completes the job by, well in this case just by calling DOUBLE again :-) + And NEXT just completes the job by, well, in this case just by calling DOUBLE again :-) LITERALS ---------------------------------------------------------------------- @@ -1043,10 +1050,13 @@ code_\label : // assembler code follows subl %eax,(%ebx) // add it NEXT -/* ! and @ (STORE and FETCH) store 32-bit words. It's also useful to be able to read and write bytes. - * Byte-oriented operations only work on architectures which permit them (i386 is one of those). - * UPDATE: writing a byte to the dictionary pointer is called C, (CCOMMA) in FORTH. +/* + ! and @ (STORE and FETCH) store 32-bit words. It's also useful to be able to read and write bytes + so we also define standard words C@ and C!. + + Byte-oriented operations only work on architectures which permit them (i386 is one of those). */ + defcode "C!",2,,STOREBYTE pop %ebx // address to store at pop %eax // data to store there @@ -1120,7 +1130,7 @@ var_\name : DOCOL Pointer to DOCOL. F_IMMED The IMMEDIATE flag's actual value. F_HIDDEN The HIDDEN flag's actual value. - F_LENMASK The length mask. + F_LENMASK The length mask in the flags/len byte. */ .macro defconst name, namelen, flags=0, label, value -- 1.8.3.1