msdos/int25.c

   1 /*
   2  * DOS interrupt 25h handler
   3  */
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <fcntl.h>
   9 #include <unistd.h>
  10 #include "msdos.h"
  11 #include "ldt.h"
  12 #include "miscemu.h"
  13 #include "drive.h"
  14 #include "stddebug.h"
  15 /* #define DEBUG_INT */
  16 #include "debug.h"
  17
  18 /**********************************************************************
  19  *          INT_Int25Handler
  20  *
  21  * Handler for int 25h (absolute disk read).
  22  */
  23 void WINAPI INT_Int25Handler( CONTEXT *context )
  24 {
  25     BYTE *dataptr = PTR_SEG_OFF_TO_LIN( DS_reg(context), BX_reg(context) );
  26     DWORD begin, length;
  27     int fd;
  28
  29     if (!DRIVE_IsValid(AL_reg(context)))
  30     {
  31         SET_CFLAG(context);
  32         AX_reg(context) = 0x0101;        /* unknown unit */
  33         return;
  34     }
  35
  36     if (CX_reg(context) == 0xffff)
  37     {
  38         begin   = *(DWORD *)dataptr;
  39         length  = *(WORD *)(dataptr + 4);
  40         dataptr = (BYTE *)PTR_SEG_TO_LIN( *(SEGPTR *)(dataptr + 6) );
  41     }
  42     else
  43     {
  44         begin  = DX_reg(context);
  45         length = CX_reg(context);
  46     }
  47     dprintf_int( stdnimp, "int25: abs diskread, drive %d, sector %ld, "
  48                  "count %ld, buffer %d\n",
  49                  AL_reg(context), begin, length, (int) dataptr);
  50
  51     if ((fd = DRIVE_OpenDevice( AL_reg(context), O_RDONLY )) != -1)
  52     {
  53         lseek( fd, begin * 512, SEEK_SET );
  54         /* FIXME: check errors */
  55         read( fd, dataptr, length * 512 );
  56         close( fd );
  57     }
  58     else
  59     {
  60         memset(dataptr, 0, length * 512);
  61         if (begin == 0 && length > 1) *(dataptr + 512) = 0xf8;
  62         if (begin == 1) *dataptr = 0xf8;
  63     }
  64     RESET_CFLAG(context);
  65 }