Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!munnari.oz.au!uhccux!mikem
From: mikem@uhccux.uhcc.hawaii.edu (Mike Morton)
Newsgroups: comp.sys.mac.programmer
Subject: Re: alloca for Think C 4.0: here it is
Keywords: alloca Think C
Message-ID: <6521@uhccux.uhcc.hawaii.edu>
Date: 9 Feb 90 05:38:06 GMT
References: <11376@attctc.Dallas.TX.US>
Reply-To: mikem@uhccux.UUCP (Mike Morton)
Organization: University of Hawaii
Lines: 19

Jay Finger writes:
>pascal void *alloca(long size) =
>  {
>    0x201F,            /* MOVE.L  (SP)+,D0   ;get size                */
>    0x5680,            /* ADDQ.L  #3,D0      ;make it a multiple of 4 */
>    0x0240, 0xFFFC,    /* ANDI.W  #-4,D0                              */
>    0x9FC0,            /* SUB.L   D0,SP      ;allocate it             */
>    0x2F0F             /* MOVE.L  SP,-(SP)   ;return value on stack   */
>  };

Since the "calling" C code has already done something like a:
       SUBQ #4, SP
to make room for a Pascal-style returned value, then isn't this
allocating 4 bytes more than needed?  I think changing -(SP) to
just (SP) would work, but haven't tried it.

 -- Mike Morton // P.O. Box 11299, Honolulu, HI  96828, (808) 676-6966 HST
      Internet: mikem@uhccux.uhcc.hawaii.edu
    (anagrams): Mr. Machine Tool; Ethical Mormon; Chosen Immortal; etc.