From: "Carlos Alfredo Barahona FrenÁNdez" <CARLOSABF AT terra DOT es>
Newsgroups: comp.os.msdos.djgpp
Subject: Problems with Allegro
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Date: Sun, 30 Jul 2000 21:51:08 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hi, my name is Carlos Barahona,i´m working in my final career´s project and
i´m using DJGPP with ALLEGRO libraries, and i´m in a trouble:

I´m using a Pentium 200 MMX with a 1M video card,and i´m working on MS-DOS,
and when i compile and run an Allegro´s program i have a Segmentation
Fault.It happens inside Allegro code, always in set_gfx_mode, i have
followed the trace and i when i arrive to 88th line in vga.c file, it
crashes.

Here is a piece of my code:
void main(void){
int eleccion,color=0;
PALETTE defecto;
allegro_init();
eleccion='0'&0xFF;

while((eleccion=='1'&0xFF) || (eleccion=='0'&0xFF))
  {
   install_keyboard();
   printf("\n\nVAMOS A CAMBIAR EL MODO GRµFICO ...\n\n");
   printf("\nQue modo desea poner:\n\t\t0->Modo Texto\n\t\t1->Modo
13\n\t\tCualquiera->Salir\n\t\t");
   eleccion=readkey();
   if((eleccion & 0xff)=='0')
        modo_texto();
     else if((eleccion & 0xff)=='1')
             modo_13();
   else
     {
  modo_texto();
  allegro_exit();
     }
  }
}
END_OF_MAIN();
void modo_texto(void)
{
int error=0;
error=set_gfx_mode(GFX_TEXT,0,0,0,0);
if(error==-1)
  {
  printf("\nNO SE HA PODIDO PONER EL MODO TEXTO\n");
  remove_keyboard();
  }
else
    {
    remove_keyboard();
    printf("\nSE HA PUESTO CON EXITO EL MODO TEXTO\n");
    }
getch();
clrscr();
}

void modo_13(void)
{
int error=0,onda=0,opval=0,i=0,j=0;
PALETTE defecto;
error=set_gfx_mode(GFX_VGA,320,200,0,0);//Here it crashes
if(error==-1)
  {
  printf("\nNO SE HA PODIDO PONER EL MODO 13\n");
  remove_keyboard();
  }
else
    {



And here the piece of code where it crashes(inside Allegro´s code):

   if ((w == 320) && (h == 200) && (v_w <= 320) && (v_h <= 200)) {
      /* standard mode 13h */
      b = _make_bitmap(320, 200, 0xA0000, &gfx_vga, 8, 320);
      if (!b)
  return NULL;

      r.x.ax = 0x13;
      __dpmi_int(0x10, &r);//Here it crashes


I have recompile Allegro as the FAQ says:


Note: if the crash happens deep inside an Allegro function, this traceback
may not be so useful. When this happens you can recompile Allegro with
debugging information (in your Allegro directory, run "make clean", "set
DEBUGMODE=1", and "make install", but note that this requires the GNU
fileutils package to be installed), and then recompile your program to use
the debugging library. Don't forget to rebuild a normal Allegro version (as
above, but "set DEBUGMODE=") when you are done, because the debugging lib is
very slow.


And i have the same results.I don´t know why it always crashes.

Sorry for my bad English(i have forgotten it as you can read)

Carlos Barahona.(Spain).