Message-ID:	<386E0E85.6925D65@connection.com>
Date:	Sat, 01 Jan 2000 09:26:17 -0500
From:	sam <samirw AT connection DOT com>
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Spilling registers - inline asm?
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X-Trace:	1 Jan 2000 09:40:07 -0500, pm4-25.connection.com
Lines:	176
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

Sorry, if this is not the right place to ask this but I have e-mailed
the author several days ago but no response, and soon  it's back to
work.

First, I will ask where can I get some info on inline assembler (if any,
I couldn't find anything in RHIDE/help stdlib or djgpp text
documentation.)

My immediate problem is with one of the GRX23 library source and I don't
even have a clue what I am looking at, although I do know assembler.
----------------------------
/**
 ** SHIFTSCL.C ---- shift and copy an array (scanline)
 **                 for 1bpp and 4bpp frame driver blit operations
 **
 ** Copyright (c) 1998 Hartmut Schirmer
 **
 **/

#include "libgrx.h"
#include "highlow.h"

#ifdef __TURBOC__
#pragma inline
#endif

void _GR_shift_scanline(GR_int8u far **dst,
   GR_int8u far **src,
   int ws, int shift, int planes) {
  int plane;

  GRX_ENTER();
  if (shift <= 0) {
    shift = -shift;
    for (plane = 0; plane < planes; ++plane) {
      GR_int8u far *s = *(src++) + ws;
      GR_int8u far *d = *(dst++) + ws;
#     if defined(__GNUC__) && defined(__i386__)
 int w = ws;
 /* sad but true: the x86 bytesex forces this inefficient code :( */
 asm volatile ("\n"
   "   movb    (%3),%%ch    \n"
   "   jmp     1f           \n"
   "   .align  4,0x90       \n"
   "1: decl    %3           \n"
   "   movb    %%ch,%%al    \n"
   "   movb    (%3),%%ah    \n"
   "   movb    %%ah,%%ch    \n"
   "   shrl    %%cl,%%eax   \n"
   "   movb    %%al,(%4)    \n"
   "   decl    %4           \n"
   "   decl    %5           \n"
   "   jne     1b           \n"
   "   shrb    %%cl,%%ch    \n"
   "   movb    %%ch,(%4)      "
   : "=r" ((void *)s), "=r" ((void *)d), "=r" ((int)w)
   : "0" ((void *)s), "1" ((void *)d), "2" ((int)w), "c" ((int)shift)
   : "ax", "cx"
 );
??/* HERE problem */
#     elif defined(__TURBOC__)
 asm     push  ds           ;
 asm     mov   bx, ws       ;
 asm     mov   cl, shift    ;
 asm     les   di, d        ;
 asm     lds   si, s        ;
 asm     mov   ch,[si]      ;
 asm     std                ;
  looprv:
 asm     dec   si           ;
 asm     mov   al, ch       ;
 asm     mov   ah, [si]     ;
 asm     mov   ch, ah       ;
 asm     shr   ax, cl       ;
 asm     stosb              ;
 asm     dec   bx           ;
 asm     jnz   short looprv ;
 asm     mov   al, ch       ;
 asm     shr   al, cl       ;
 asm     stosb              ;
 asm     pop   ds           ;
#     else
 int w = ws;
 do {
   --s;
   *(d--) = highlowP(s)>>shift;
 } while (--w);
 *d = *s >> shift;
#     endif
    }
  } else {
    shift = 8-shift;
    for (plane = 0; plane < planes; ++plane) {
      GR_int8u far *s = *(src++);
      GR_int8u far *d = *(dst++);
#     if defined(__GNUC__) && defined(__i386__)
 int w = ws;
 asm volatile ("\n"
   "   movb    (%3),%%ch    \n"
   "   jmp     1f           \n"
   "   .align  4,0x90       \n"
   "1: incl    %3           \n"
   "   movb    %%ch,%%ah    \n"
   "   movb    (%3),%%al    \n"
   "   movb    %%al,%%ch    \n"
   "   shrl    %%cl,%%eax   \n"
   "   movb    %%al,(%4)    \n"
   "   incl    %4           \n"
   "   decl    %5           \n"
   "   jne     1b             "
   : "=r" ((void *)s), "=r" ((void *)d), "=r" ((int)w)
   : "0" ((void *)s), "1" ((void *)d), "2" ((int)w), "c" ((int)shift)
   : "ax", "cx"
 );
#     elif defined(__TURBOC__)
 asm     push  ds           ;
 asm     mov   bx, ws       ;
 asm     mov   cl, shift    ;
 asm     les   di, d        ;
 asm     lds   si, s        ;
 asm     mov   ch,[si]      ;
 asm     cld                ;
  loopfw:
 asm     inc   si           ;
 asm     mov   ah, ch       ;
 asm     mov   al, [si]     ;
 asm     mov   ch, al       ;
 asm     shr   ax, cl       ;
 asm     stosb              ;
 asm     dec   bx           ;
 asm     jnz   short loopfw ;
 asm     pop   ds           ;
#     else
 int w = ws;
 do {
   *(d++) = highlowP(s)>>shift /* sh */;
   s++;
 } while (--w);
#     endif
    }
  }
  GRX_LEAVE();
}

------------------------------------
The following is a screen dump of the error I am getting when compiling
the library for djgpp 2 from a DOS shell from RHIDE (32 Mb ram).

 2:54:19.68
D:\DJGPP\CONTRIB\grx23\src>make -f makefdj2.mak
gcc -c -O6 -Wall -fomit-frame-pointer -I. -I./include -I../include
-I../addons/p
rint -I../addons/bmp utils/shiftscl.c -o utils/shiftscl.o
utils/shiftscl.c: In function `_GR_shift_scanline':
utils/shiftscl.c:48: Invalid `asm' statement:
utils/shiftscl.c:48: fixed or forbidden register 2 (cx) was spilled for
class CR
EG.
utils/shiftscl.c:102: Invalid `asm' statement:
utils/shiftscl.c:102: fixed or forbidden register 2 (cx) was spilled for

class C
REG.
make.exe: *** [utils/shiftscl.o] Error 1

Sounds like parser limitation, but I have no idea what to do about it.
Any help grately appreciated.

Cheers and happy new (1K-24)
Oh ya, I am using 486 (no MMX registers) if that makes any difference.

-----------------------------------------------
I guess I better start liking mainframes, can't have all this s--t
spilling all over the place.

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