/* $NetBSD: bios_disk.S,v 1.23 2022/09/10 12:14:17 rillig Exp $ */ /* * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992 * * Mach Operating System * Copyright (c) 1992, 1991 Carnegie Mellon University * All Rights Reserved. * * Permission to use, copy, modify and distribute this software and its * documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie Mellon * the rights to redistribute these changes. */ /* Copyright 1988, 1989, 1990, 1991, 1992 by Intel Corporation, Santa Clara, California. All Rights Reserved Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies and that both the copyright notice and this permission notice appear in supporting documentation, and that the name of Intel not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* extracted from netbsd:sys/arch/i386/boot/bios.S */ #include <machine/asm.h> /* * BIOS call "INT 0x13 Function 0x0" to reset the disk subsystem * Call with %ah = 0x0 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) * Return: * %al = 0x0 on success; err code on failure */ ENTRY(biosdisk_reset) pusha movb %al, %dl # device call _C_LABEL(prot_to_real) # enter real mode .code16 movb $0x0, %ah # subfunction int $0x13 setc %bl movb %ah, %bh # save error code calll _C_LABEL(real_to_prot) # back to protected mode .code32 movzwl %bx, %eax # return value in %eax movl %eax, 28(%esp) popa ret /* * BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory * Call with %ah = 0x2 * %al = number of sectors * %ch = cylinder * %cl = sector * %dh = head * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) * %es:%bx = segment:offset of buffer * Return: * %al = 0x0 on success; err code on failure * * biosdisk_read(dev, cyl, head, sect, count, buff_addr); * * Note: On failure, you must reset the disk with biosdisk_reset() before * sending another command. */ ENTRY(biosdisk_read) pusha movb 44(%esp), %dh movw 40(%esp), %cx xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl rorb $2, %cl movb 48(%esp), %al orb %al, %cl incb %cl # sector; sec starts from 1, not 0 movb 36(%esp), %dl # device movl 56(%esp), %ebx # buffer address (may be >64k) movb 52(%esp), %al # number of sectors call _C_LABEL(prot_to_real) # enter real mode .code16 push %bx shrl $4, %ebx # max segment mov %ds, %si add %si, %bx mov %bx, %es # %es:%bx now valid buffer address pop %bx and $0xf, %bx # and min offset - to avoid overrun movb $0x2, %ah # subfunction int $0x13 setc %al # error code is in %ah calll _C_LABEL(real_to_prot) # back to protected mode .code32 andl $0x0000FFFF, %eax # Some bioses set high bits in %eax # on success, interfering with our # return value. Clear those out. movl %eax, 28(%esp) popa ret /* * biosdisk_getinfo(int dev): return a word that represents the * max number of sectors, heads and cylinders for this device */ ENTRY(biosdisk_getinfo) push %es pusha movb %al, %dl # diskinfo(drive #) call _C_LABEL(prot_to_real) # enter real mode .code16 push %dx # save drive # movb $0x08, %ah # ask for disk info int $0x13 pop %bx # restore drive # jnc ok testb $0x80, %bl # is it a hard disk? jnz ok /* * Urk. Call failed. It is not supported for floppies by old BIOS's. * Guess it's a 15-sector floppy. Initialize all the registers for * documentation, although we only need head and sector counts. */ xorw %ax, %ax # set status to success # movb %ah, %bh # %bh = 0 # movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M movb $79, %ch # max track movb $15, %cl # max sector movb $1, %dh # max head # movb $1, %dl # # floppy drives installed # es:di = parameter table # carry = 0 ok: calll _C_LABEL(real_to_prot) # back to protected mode .code32 /* form a longword representing all this gunk */ shrl $8, %eax # clear unnecessary bits shll $24, %eax shll $16, %ecx # do the same for %ecx shrl $8, %ecx movb %dh, %cl # max head orl %ecx, %eax # return value in %eax movl %eax, 28(%esp) popa pop %es ret /* * int biosdisk_int13ext(int dev): * check for availability of int13 extensions. */ ENTRY(biosdisk_int13ext) pusha movb %al, %dl # drive # movw $0x55aa, %bx call _C_LABEL(prot_to_real) # enter real mode .code16 movb $0x41, %ah # ask for disk info int $0x13 setnc %dl calll _C_LABEL(real_to_prot) # switch back .code32 movzbl %dl, %eax # return value in %eax cmpw $0xaa55, %bx sete %dl andb %dl, %al andb %cl, %al movl %eax, 28(%esp) popa ret /* * BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory * Call with %ah = 0x42 * %ds:%si = parameter block (data buffer address * must be a real mode physical address). * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) * Return: * %al = 0x0 on success; err code on failure */ ENTRY(biosdisk_extread) pusha movl %edx, %esi # parameter block movb %al, %dl # device call _C_LABEL(prot_to_real) # enter real mode .code16 push %ds movl %esi, %eax shrl $4, %eax movw %ds, %bx addw %bx, %ax movw %ax, %ds andw $0xf, %si movb $0x42, %ah # subfunction int $0x13 setc %bl movb %ah, %bh # save error code pop %ds calll _C_LABEL(real_to_prot) # back to protected mode .code32 movzwl %bx, %eax # return value in %eax movl %eax, 28(%esp) popa ret ENTRY(biosdisk_getextinfo) pusha movl %edx, %esi # parameter block movb %al, %dl # device call _C_LABEL(prot_to_real) # enter real mode .code16 push %ds movl %esi, %eax shrl $4, %eax andw $0xf, %si movw %ds, %bx addw %bx, %ax movw %ax, %ds movb $0x48, %ah # subfunction int $0x13 setc %bl pop %ds calll _C_LABEL(real_to_prot) # back to protected mode .code32 movzbl %bl, %eax # return value in %eax movl %eax, 28(%esp) popa ret
