Sweden-Number/msdos/int25.c

65 lines
1.6 KiB
C

/*
* DOS interrupt 25h handler
*/
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include "msdos.h"
#include "ldt.h"
#include "miscemu.h"
#include "drive.h"
#include "debug.h"
/**********************************************************************
* INT_Int25Handler
*
* Handler for int 25h (absolute disk read).
*/
void WINAPI INT_Int25Handler( CONTEXT *context )
{
BYTE *dataptr = CTX_SEG_OFF_TO_LIN( context, DS_reg(context), EBX_reg(context) );
DWORD begin, length;
int fd;
if (!DRIVE_IsValid(AL_reg(context)))
{
SET_CFLAG(context);
AX_reg(context) = 0x0101; /* unknown unit */
return;
}
if (CX_reg(context) == 0xffff)
{
begin = *(DWORD *)dataptr;
length = *(WORD *)(dataptr + 4);
dataptr = (BYTE *)CTX_SEG_OFF_TO_LIN( context,
*(WORD *)(dataptr + 8), *(DWORD *)(dataptr + 6) );
}
else
{
begin = DX_reg(context);
length = CX_reg(context);
}
TRACE(int, "int25: abs diskread, drive %d, sector %ld, "
"count %ld, buffer %d\n",
AL_reg(context), begin, length, (int) dataptr);
if ((fd = DRIVE_OpenDevice( AL_reg(context), O_RDONLY )) != -1)
{
lseek( fd, begin * 512, SEEK_SET );
/* FIXME: check errors */
read( fd, dataptr, length * 512 );
close( fd );
}
else
{
memset(dataptr, 0, length * 512);
if (begin == 0 && length > 1) *(dataptr + 512) = 0xf8;
if (begin == 1) *dataptr = 0xf8;
}
RESET_CFLAG(context);
}