Xref: news2.mv.net comp.os.msdos.djgpp:3731
From: 004277a AT news DOT acadiau DOT ca (Hafiz Awang Pon)
Newsgroups: comp.os.msdos.djgpp
Subject: inline assmembly error problem
Date: 12 May 96 05:46:04 GMT
Organization: Dalhousie University
Lines: 58
Message-ID: <31957b1c.0@131.162.2.91>
NNTP-Posting-Host: iceberg.acadiau.ca
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp


i've got a couple question:

i) I've written this inline assembly procedure for drawing a groud shaded line

void gline(unsigned char *dest, int val, int step, int length) {
   
   asm ("movw %0,%%dx":: "g" (step):"%dx");
   asm ("movw %0,%%cx":: "g" (length):"%cx");
   asm ("movl %0,%%edi":: "g" (dest):"%edi");
   asm ("movw %0,%%ax":: "g" (val):"%ax");
   asm ("grdagain: movb %ah, (%edi)");
   asm ("addw %dx, %ax");
   asm ("inc %edi");
   asm ("dec %cx");
   asm ("jnz grdagain");
   }

I use this routine to draw to a screen buffer which later will
be copied to the screen. On my previous version of (written
in djgppv1) the program it works. My question is when compiled,
it gives the error that the opcode is not understood(operands 
dont't match any 386 instructions, symbol grdagain already 
defined, etc). The thing is (this question might be relevant 
or not to answer the question). When the program is compiled 
without any part of the program using that procedure, no 
error is reported. But when compile with a program that 
uses it such as

  gline(&((*v).line[y][x1]), colorvalue, step, length);

it gives the previously mentioned error. What basically i'm
attempting to do is to use the allegro library, so that 
my engine will also have svga capabilites. My first hunch
was that maybe such manipulation is not allowed but when i test
the same method on my flat shaded line drawing procedure;

void bstore(unsigned char *dest, unsigned char val, int size) {
   
   asm ("cld");
   asm ("movl %0,%%ecx":: "g" (size):"%ecx");
   asm ("movb %0,%%al":: "g" (val):"%al");
   asm ("movl %0,%%edi":: "g" (dest):"%edi");
   asm ("rep");
   asm ("stosb %al, (%edi)");
   }

bstore(&((*v).line[y][x1]), polyc, (x2 - x1 + 1));

it works. This is a very confusing problem. I spend nights
trying to get around it but to no avail. I need to get this
procedure to work because it's a very crucial part of my 
engine. I also have an inline procedure which draws a textured
line but i don't dare to test it yet until this problem is solved
thanks in advance

004277a AT dragon DOT acadiau DOT ca
http://dragon.acadiau.ca/~004277a