Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!dartvax!eleazar.dartmouth.edu!earleh
From: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Question about Bison
Summary: Alloca() source!
Message-ID: <10329@dartvax.Dartmouth.EDU>
Date: 10 Oct 88 01:18:38 GMT
References: <8246@cit-vax.Caltech.Edu>
Sender: news@dartvax.Dartmouth.EDU
Reply-To: earleh@eleazar.dartmouth.edu (Earle R. Horton)
Organization: Thayer School of Engineering
Lines: 52

In article <8246@cit-vax.Caltech.Edu> janin@tybalt.caltech.edu 
	(Adam L. Janin) writes:
>I just installed Bison on a Mac II and I'm having a problem when linking.
>Using bison.simple, I get a link error (missing functions alloca and bcopy).
>When I use bison.hairy (using the %semantic_parser command), I get other link
>errors (several missing functions).  I assume I should simply replace 
>alloca with NewPtr and bcopy with MemCopy.  Is this correct?  Also, under
>what conditions would I want to use bison.hairy as apposed to bison.simple?

Alloca() is a non-portable function that allocates storage in the
local stack frame of the caller.  Said storage vanishes when the
caller of alloca() returns.  The stack frame convention used in MPW
high level languages makes implementation of alloca() trivial, as
shown below.  Bcopy() is similar to BlockMove() and to memcpy().
Memcpy() is more portable to use because I think it is in ANSI C(?).

I compiled the original GNU sources for Bison from prep.ai.mit.edu on
my Mac II with little difficulty.  However, I have yet to use the
"%semantic_parser" command or to figure out what it is for, although I
did notice that it generates link errors.  I also got the posted
sources by Pierce T. Wetter, and compiled them.  I notice that
bison.hairy does not work there either.  My feeling is that Pierce did
not get it working, but you might ask him, since his mail address is
also at Tybalt.Caltech.Edu.

This is the assembler source to alloca() for use with Macintosh
Programmer's Workshop C.  Notice that it must be assembled with MPW
assembler.  If you do not have the assembler, then I can whip up a C
version using InLines if you like.

;;
;; Alloca() for Macintosh Programmer's Workshop C.
;; alloca(n) allocates n bytes of storage in the stack
;; frame of the caller.
;;
	CASE ON
	
alloca PROC EXPORT
        move.l  (sp)+,a0        ; pop return address
        move.l  (sp)+,d0        ; pop parameter = size in bytes
        add.l   #3,d0       	; round size up to long word
        and.l   #-4,d0        	; mask out lower two bits of size
        sub.l   d0,sp           ; allocate by moving stack pointer
        move.l  sp,d0           ; return pointer
        add.l   #-4,sp          ; new top of stack
        jmp     (a0)            ; return to caller
        ENDP
	END
		
Earle R. Horton. 23 Fletcher Circle, Hanover, NH 03755
(603) 643-4109
Sorry, no fancy stuff, since this program limits my .signature to three