miscemu/int25.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include "registers.h"
   5 #include "msdos.h"
   6 #include "ldt.h"
   7 #include "wine.h"
   8 #include "miscemu.h"
   9 #include "drive.h"
  10 #include "stddebug.h"
  11 /* #define DEBUG_INT */
  12 #include "debug.h"
  13
  14 /**********************************************************************
  15  *          INT_Int25Handler
  16  *
  17  * Handler for int 25h (absolute disk read).
  18  */
  19 void INT_Int25Handler( struct sigcontext_struct context )
  20 {
  21     BYTE *dataptr = PTR_SEG_OFF_TO_LIN( DS_reg(&context), BX_reg(&context) );
  22     DWORD begin, length;
  23
  24     if (!DRIVE_IsValid(AL_reg(&context)))
  25     {
  26         SET_CFLAG(&context);
  27         AX_reg(&context) = 0x0101;        /* unknown unit */
  28         return;
  29     }
  30
  31     if (CX_reg(&context) == 0xffff)
  32     {
  33         begin   = *(DWORD *)dataptr;
  34         length  = *(WORD *)(dataptr + 4);
  35         dataptr = (BYTE *)PTR_SEG_TO_LIN( *(SEGPTR *)(dataptr + 6) );
  36     }
  37     else
  38     {
  39         begin = DX_reg(&context);
  40         length = CX_reg(&context);
  41     }
  42     dprintf_int( stdnimp, "int25: abs diskread, drive %d, sector %ld, "
  43                  "count %ld, buffer %d\n",
  44                  AL_reg(&context), begin, length, (int) dataptr);
  45
  46     memset(dataptr, 0, length * 512);
  47
  48     if (begin == 0 && length > 1) *(dataptr + 512) = 0xf8;
  49
  50     if (begin == 1) *dataptr = 0xf8;
  51
  52     RESET_CFLAG(&context);
  53 }