/* ----------------------------------------------------------------------- *
*
* Copyright 2009 Shao Miller - All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
* Boston MA 02111-1307, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* dskprobe.c
*
* Routines for probing BIOS disk drives
*/
/* Change to 1 for debugging */
#define DBG_DSKPROBE 0
#include <stdint.h>
#include "memdisk.h"
#include "bda.h"
#include "conio.h"
/* Function type for printf() */
typedef int (f_printf) (const char *, ...);
/* Dummy printf() that does nothing */
static f_printf no_printf;
static f_printf *dskprobe_printfs[] = { no_printf, printf };
#define dskprobe_printf (dskprobe_printfs[DBG_DSKPROBE])
static void dskprobe_pause(com32sys_t *);
/* Probe routine function type */
typedef int (f_probe) (uint8_t, com32sys_t *);
static f_probe probe_int13h_08h, probe_int13h_15h, probe_int13h_41h;
/* We will probe a BIOS drive number using INT 0x13, AH == func */
static void probe_any(uint8_t func, uint8_t drive, com32sys_t * regs)
{
regs->eax.b[1] = func; /* AH == sub-function for probe */
regs->edx.b[0] = drive; /* DL == drive number to probe */
intcall(0x13, regs, regs);
return;
}
/**
* Determine if the return from probe_int13h_01h indicates a failure; a
* return of zero indicates no known failure.
*/
static int probe_int13h_01h_fail(int istatus)
{
int status = 0;
if (istatus >= 256)
status = istatus;
else
switch (istatus) {
case 1: status = istatus;
}
return status;
}
/**
* INT 0x13, AH == 0x01: Get status of last command.
*/
static int probe_int13h_01h(uint8_t drive)
{
int status;
com32sys_t regs;
memset(®s, 0, sizeof regs);
probe_any(0x01, drive, ®s);
status = (regs.eflags.l & 1) * 256 + regs.eax.b[1];
dskprobe_printf(" AH01: CF%d AH%02x", regs.eflags.l & 1, regs.eax.b[1]);
return status;
}
/**
* INT 0x13, AH == 0x08: Get drive parameters.
*/
static int probe_int13h_08h(uint8_t drive, com32sys_t * regs)
{
int present;
int status;
memset(regs, 0, sizeof *regs);
probe_any(0x08, drive, regs);
dskprobe_printf(" AH08: CF%d AH%02x AL%02x BL%02x DL%02x ",
regs->eflags.l & 1, regs->eax.b[1], regs->eax.b[0],
regs->ebx.b[0], regs->edx.b[0]);
present = !(regs->eflags.l & 1) && !regs->eax.b[1];
status = probe_int13h_01h(drive);
present = present && !(probe_int13h_01h_fail(status));
dskprobe_printf(" P%d\n", present);
return present;
}
/**
* INT 0x13, AH == 0x15: Get disk type.
*/
static int probe_int13h_15h(uint8_t drive, com32sys_t * regs)
{
int present;
int status;
memset(regs, 0, sizeof *regs);
probe_any(0x15, drive, regs);
dskprobe_printf(" AH15: CF%d AH%02x AL%02x CX%04x DX%04x",
regs->eflags.l & 1, regs->eax.b[1], regs->eax.b[0],
regs->ecx.w[0], regs->edx.w[0]);
present = !(regs->eflags.l & 1) && regs->eax.b[1];
status = probe_int13h_01h(drive);
present = present && !(probe_int13h_01h_fail(status));
dskprobe_printf(" P%d\n", present);
return present;
}
/**
* INT 0x13, AH == 0x41: INT 0x13 extensions installation check.
*/
static int probe_int13h_41h(uint8_t drive, com32sys_t * regs)
{
int present;
int status;
memset(regs, 0, sizeof *regs);
regs->ebx.w[0] = 0x55AA; /* BX == 0x55AA */
probe_any(0x41, drive, regs);
dskprobe_printf(" AH41: CF%d AH%02x BX%04x CX%04x DH%02x",
regs->eflags.l & 1, regs->eax.b[1], regs->ebx.w[0],
regs->ecx.w[0], regs->edx.b[1]);
present = !(regs->eflags.l & 1) && (regs->ebx.w[0] == 0xAA55);
status = probe_int13h_01h(drive);
present = present && !(probe_int13h_01h_fail(status));
dskprobe_printf(" P%d\n", present);
return present;
}
/*
* We will probe the BIOS Data Area and count the drives found there.
* This heuristic then assumes that all drives of 'drive's type are
* found in a contiguous range, and returns 1 if the probed drive
* is less than or equal to the BDA count.
* This particular function's code is derived from code in setup.c by
* H. Peter Anvin. Please respect that file's copyright for this function
*/
int probe_bda_drive(uint8_t drive)
{
int bios_drives;
int err;
if (drive & 0x80) {
bios_drives = rdz_8(BIOS_HD_COUNT); /* HDD count */
} else {
uint8_t equip = rdz_8(BIOS_EQUIP);
if (equip & 1)
bios_drives = (equip >> 6) + 1; /* Floppy count */
else
bios_drives = 0;
}
err = (drive - (drive & 0x80)) >= bios_drives ? 0 : 1;
dskprobe_printf("BDA drive %02x? %d, total count: %d\n", drive, err,
bios_drives);
return err;
}
/*
* We will probe a drive with a few different methods, returning
* the count of succesful probes
*/
int multi_probe_drive(uint8_t drive)
{
int c = 0;
com32sys_t regs;
dskprobe_printf("INT 13 DL%02x:\n", drive);
/* Only probe the BDA for floppies */
if (drive & 0x80) {
c += probe_int13h_08h(drive, ®s);
c += probe_int13h_15h(drive, ®s);
c += probe_int13h_41h(drive, ®s);
}
c += probe_bda_drive(drive);
dskprobe_pause(®s);
return c;
}
/*
* We will probe a contiguous range of BIOS drive, starting with drive
* number 'start'. We probe with a few different methods, and return
* the first drive which doesn't respond to any of the probes.
*/
uint8_t probe_drive_range(uint8_t start)
{
uint8_t drive = start;
while (multi_probe_drive(drive)) {
drive++;
/* Check for passing the floppy/HDD boundary */
if ((drive & 0x7F) == 0)
break;
}
return drive;
}
/* Dummy printf() that does nothing */
static int no_printf(const char *ignored, ...)
{
(void)ignored;
return 0;
}
/* Pause if we are in debug-mode */
static void dskprobe_pause(com32sys_t * regs)
{
if (!DBG_DSKPROBE)
return;
dskprobe_printf("Press a key to continue...\n");
memset(regs, 0, sizeof *regs);
regs->eax.w[0] = 0;
intcall(0x16, regs, NULL);
return;
}