msdos/int25.c

   1 /*
   2  * DOS interrupt 25h handler
   3  */
   4
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <fcntl.h>
   8 #include <unistd.h>
   9 #include "msdos.h"
  10 #include "ldt.h"
  11 #include "miscemu.h"
  12 #include "drive.h"
  13 #include "debugtools.h"
  14
  15 DEFAULT_DEBUG_CHANNEL(int)
  16
  17
  18 /**********************************************************************
  19  *          INT_Int25Handler
  20  *
  21  * Handler for int 25h (absolute disk read).
  22  */
  23 void WINAPI INT_Int25Handler( CONTEXT86 *context )
  24 {
  25     BYTE *dataptr = CTX_SEG_OFF_TO_LIN( context, DS_reg(context), EBX_reg(context) );
  26     DWORD begin, length;
  27
  28     if (!DRIVE_IsValid(AL_reg(context)))
  29     {
  30         SET_CFLAG(context);
  31         AX_reg(context) = 0x0201;        /* unknown unit */
  32         return;
  33     }
  34
  35     if (CX_reg(context) == 0xffff)
  36     {
  37         begin   = *(DWORD *)dataptr;
  38         length  = *(WORD *)(dataptr + 4);
  39         dataptr = (BYTE *)CTX_SEG_OFF_TO_LIN( context,
  40                                         *(WORD *)(dataptr + 8), *(DWORD *)(dataptr + 6) );
  41     }
  42     else
  43     {
  44         begin  = DX_reg(context);
  45         length = CX_reg(context);
  46     }
  47     TRACE("int25: abs diskread, drive %d, sector %ld, "
  48                  "count %ld, buffer %p\n",
  49                  AL_reg(context), begin, length, dataptr);
  50
  51         DRIVE_RawRead(AL_reg(context), begin, length, dataptr, TRUE);
  52     RESET_CFLAG(context);
  53 }
  54