/* Non-DOS formats count as formats as well! (Eric) */
char Check_For_Format(void)
{
union REGS regs;
regs.h.ah = 0x0d; /* this is in Check_For_Format */
intdos(®s,®s); /* flush buffers, reset disk system */
if (debug_prog==TRUE) printf("[DEBUG] Test-reading boot sector.\n");
/* as int 21.32 does not work for FAT32, we ALWAYS read the boot sector */
param.fat_type = FAT16; /* Check_For_Format: guess "not FAT32" first */
regs.x.ax = Drive_IO(READ, 0, -1);
if ((regs.x.ax != 0) && (param.drive_type != FLOPPY))
{
/*
* if (debug_prog==TRUE) printf("[DEBUG] Trying again in FAT32 mode.\n");
*/
if (debug_prog==TRUE) printf(" maybe FAT32?\n");
param.fat_type = FAT32; /* Check_ForFormat: try FAT32 Drive_IO next */
regs.x.ax = Drive_IO(READ, 0, -1);
if (regs.x.ax != 0)
param.fat_type = FAT16; /* Check_For_Format: revert to FAT1x Drive_IO */
}
if (regs.x.ax != 0) /* could not even read boot sector */
{
if (debug_prog==TRUE) printf("[DEBUG] Error code: 0x%x\n", regs.x.ax);
/* bits: 80 timeout 40 seek 20 controller fail 10 CRC error */
/* 8 DMA error 4 sector not found 2 bad address mark 1 bad command */
/* (int 26 would have special extra code 3, write protect error) */
printf(" Boot sector unreadable, disk not yet formatted\n");
return FALSE;
}
/* test if sectors per track are 1..63, if the 55 aa magic is, */
/* present and if the bytes per sector word has the value 512 */
/* added 0.91v as MS DOS criterrs on int 21.32 if no FAT file- */
/* system is present on disk. problem found by Alain Mouette. */
if ((sector_buffer[0x18]>63) || (sector_buffer[0x18]==0) ||
(sector_buffer[0x1fe]!=0x55) || (sector_buffer[0x1ff]!=0xaa) ||
(sector_buffer[0x0b]!=0) || (sector_buffer[0x0c]!=2))
{
printf(" Boot sector contents implausible, disk not yet FAT formatted\n");
return FALSE;
}
if (param.fat_type == FAT32)
{
/* if (debug_prog==TRUE) printf("[DEBUG] Checking xBPB (FAT32)\n"); */
regs.x.ax = 0x7302; /* this is in Check_For_Format */ /* read xBPB */
regs.h.dl = param.drive_number + 1; /* 0 default 1 A: 2 B: ... */
regs.x.di = FP_OFF(§or_buffer[0]);
sregs.es = FP_SEG(§or_buffer[0]);
regs.x.cx = 0x3f; /* amount of to-be-used buffer size */
regs.x.si = 0; /* (can be a magic value to get more data) */
regs.x.cflag = 0;
intdosx(®s,®s,&sregs); /* read xBPB for that drive */
if (regs.x.cflag == 0)
regs.x.ax = 0; /* call worked */
}
else
{
/* if (debug_prog==TRUE) printf("[DEBUG] Checking DPB/BPB (FAT1x)\n"); */
regs.h.ah = 0x32; /* this is in Check_For_Format */ /* read BPB/DPB */
regs.h.dl = param.drive_number + 1; /* 0 default 1 A: 2 B: ... */
intdosx(®s,®s,&sregs); /* re-read info for that drive */
/* this can cause a critical error if boot sector not readable! */
regs.h.ah = 0;
}
if (regs.x.ax == 0)
{
/* could analyze returned DPB - pointer is DS:BX if FAT16/FAT12 */
/* could analyze returned xBPB - it is in sector_buffer if FAT32 */
if (debug_prog==TRUE) printf("[DEBUG] Existing format detected.\n");
return TRUE;
}
else
{
printf("Invalid %sBPB (code 0x%x). NOT yet formatted.\n",
((param.fat_type == FAT32) ? "x" : ""), regs.x.ax);
return FALSE; /* is this is a network drive or something? */
}
} /* Check_For_Format */
/* Non-DOS formats count as formats as well! (Eric) */
static char Check_For_Format(void)
{
regs.h.ah = 0x0d; /* this is in Check_For_Format */
__dpmi_int(0x21, ®s);; /* flush buffers, reset disk system */
#ifdef __FORMAT_DEBUG__
puts("[DEBUG] Test-reading boot sector.");
#endif
/* as int 21.32 does not work for FAT32, we ALWAYS read the boot sector */
param.fat_type = FAT16; /* Check_For_Format: guess "not FAT32" first */
regs.x.ax = Drive_IO(READ, 0, -1);
if ((regs.x.ax != 0) && (param.drive_type != FLOPPY)) {
#ifdef __FORMAT_DEBUG__
printf(" maybe FAT32?\n");
#endif
param.fat_type = FAT32; /* Check_ForFormat: try FAT32 Drive_IO next */
regs.x.ax = Drive_IO(READ, 0, -1);
if (regs.x.ax != 0)
param.fat_type = FAT16; /* Check_For_Format: revert to FAT1x Drive_IO */
}
if (regs.x.ax != 0) { /* could not even read boot sector */
#ifdef __FORMAT_DEBUG__
printf("[DEBUG] Error code: 0x%x\n", regs.x.ax);
#endif
/* bits: 80 timeout 40 seek 20 controller fail 10 CRC error */
/* 8 DMA error 4 sector not found 2 bad address mark 1 bad command */
/* (int 26 would have special extra code 3, write protect error) */
printf(" Boot sector unreadable, disk not yet formatted\n");
return FALSE;
}
if (param.fat_type == FAT32) {
/* if (debug_prog==TRUE) printf("[DEBUG] Checking xBPB (FAT32)\n"); */
regs.x.ax = 0x7302; /* this is in Check_For_Format */ /* read xBPB */
regs.h.dl = param.drive_number + 1; /* 0 default 1 A: 2 B: ... */
regs.x.es = FP_SEG(sector_buffer);
regs.x.di = FP_OFF(sector_buffer);
regs.x.cx = 0x3f; /* amount of to-be-used buffer size */
regs.x.si = 0; /* (can be a magic value to get more data) */
regs.x.flags &= ~CARRY_FLAG;
__dpmi_int(0x21, ®s);; /* read xBPB for that drive */
if (!(regs.x.flags&CARRY_FLAG))
regs.x.ax = 0; /* call worked */
} else {
regs.h.ah = 0x32; /* this is in Check_For_Format */ /* read BPB/DPB */
regs.h.dl = param.drive_number + 1; /* 0 default 1 A: 2 B: ... */
__dpmi_int(0x21, ®s);; /* re-read info for that drive */
/* this can cause a critical error if boot sector not readable! */
regs.h.ah = 0;
}
if (regs.x.ax == 0) {
/* could analyze returned DPB - pointer is DS:BX if FAT16/FAT12 */
/* could analyze returned xBPB - it is in sector_buffer if FAT32 */
#ifdef __FORMAT_DEBUG__
printf("[DEBUG] Existing format detected.\n");
#endif
return TRUE;
} else {
printf("Invalid %sBPB (code 0x%x). NOT yet formatted. Or network / CD-ROM?\n",
((param.fat_type == FAT32) ? "x" : ""), regs.x.ax);
return FALSE; /* this is a network drive or something */
}
}
