From: "Tan" <j_tan AT sympatico DOT bc DOT ca>
Newsgroups: comp.os.msdos.djgpp
Subject: General Protection Fault After 2000 movedata();
Date: 17 Jan 1997 05:54:14 GMT
Organization: Home
Lines: 111
Message-ID: <01bc0384$26a2c860$8713c2cf@586>
NNTP-Posting-Host: vanc07m02-135.bctel.ca
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

I was doing a graphics rotine, copying bitmap from one virtual memory to
linear buffer frame. I used movedata() to move memory, but after about 2000
movedata()'s, I got 

General Protection Fault at eip=000a161
eax=000000df ebx=000520e0 ecx=fff8848c edx=0000fa64 esi=00082b82
edi=00097000
ebp=000507dc esp=000507cc program=F:\GRA\TEST1.EXE
cs: sel=00af  base=82ca2000  limit=0005ffff
ds: sel=00df  base=83086000  limit=00096fff
es: sel=00d7  base=c2afa000  limit=00096fff
fs: sel=00df  base=83086000  limit=00096fff
gs: sel=00c7  base=00000000  limit=ffffffff
ss: sel=00b7  base=82ca2000  limit=0005ffff

Call frame traceback EIPs:
  0x0000a161
  0x00001e60
  0x00002fd9
  0x00003766



The function I used was:


typedef struct
{
        int id;
        int x1;
        int y1;
        int x2;
        int y2;
        int clip_flag;
        int clip_x1;
        int clip_y1;
        int clip_x2;
        int clip_y2;

        int bytes_per_pixel;
	  
	  unsigned int pal_id;	
        unsigned long linear;
        unsigned long handle;
        unsigned long size;
        int segment;
} bitmap;

AFTER I USE THIS FUNCTION FOR 146 TIMES, I WILL GET PROBLEM FOR SURE!!
I have no idea why.

int CopyBMP(bitmap s_BMP, int s_x1, int s_y1, int s_x2, int s_y2,
            bitmap d_BMP, int d_x, int d_y)
{
        int length, height, i;
        unsigned int s_offset, d_offset;
        int temp;
**********************************************************************
		Below is the clipping part which shouldn't be wrong
**********************************************************************
        if(s_x1 > s_x2) { temp = s_x1; s_x1 = s_x2; s_x2 = temp; };
        if(s_y1 > s_y2) { temp = s_y1; s_y1 = s_y2; s_y2 = temp; };

        if((s_x1 >= s_BMP.x2) || (s_y1 >= s_BMP.y2) ||
          (d_x >= d_BMP.clip_x2) || (d_y >=d_BMP.clip_y2) ||
          (s_x1 == s_x2) || (s_y1 == s_y2))
          return;

        if(s_x1 < 0) { d_x = d_x - s_x1; s_x1 = 0; }
        if(s_y1 < 0) { d_y = d_y - s_y1; s_y1 = 0; }
        if(s_x2 > s_BMP.x2) { s_x2 = s_BMP.x2; }
        if(s_y2 > s_BMP.y2) { s_y2 = s_BMP.y2; }

        if (d_x < d_BMP.clip_x1)
        {
            s_x1 = s_x1 + (d_BMP.clip_x1 - d_x);
            d_x = d_BMP.clip_x1;
        }

        if (d_y < d_BMP.clip_y1)
        {
            s_y1 = s_y1 + (d_BMP.clip_y1 - d_y);
            d_y = d_BMP.clip_y1;
        }

        if( (s_x2 - s_x1) > (d_BMP.clip_x2 - d_x) )
            s_x2 = d_BMP.clip_x2 - d_x + s_x1 + 1;
        if( (s_y2 - s_y1) > (d_BMP.clip_y2 - d_y) )
            s_y2 = d_BMP.clip_y2 - d_y + s_y1 + 1;

        s_offset = (s_BMP.x2 * s_y1 + s_x1) * s_BMP.bytes_per_pixel;
        d_offset = (d_BMP.x2 * d_y + d_x) * d_BMP.bytes_per_pixel;

        length = (s_x2 - s_x1) * s_BMP.bytes_per_pixel;
        height = s_y2 - s_y1;
**********************************************************************
	The problem after here; but I dont know why
**********************************************************************

        for (i=0; i<height; i++)
        {
          movedata(s_BMP.segment, s_offset, d_BMP.segment, d_offset,
length);
          s_offset = s_offset + s_BMP.x2 * bytes_per_pixel;
          d_offset = d_offset + d_BMP.x2 * bytes_per_pixel;
        }
}



If you know some how can solve please help me. HELP ME!!