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hdipl.S
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hdipl.S
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/* Copyright (c) 2017, Piotr Durlej
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
.globl _start
.code16
.org 0
_start:
ljmp $0x7c0, $1f
1:
movw $0x0000, %ax
movw %ax, %ss
movw $0x7c00, %sp
movw $0x7c0, %ax
movw %ax, %ds
movw $0x800, %ax
movw %ax, %es
cld
movw $0, %si
movw $0, %di
movw $128, %cx
rep
movsl
ljmp $0x800, $1f
1: movw $0x800, %ax
movw %ax, %ds
movw %ax, %fs
movw %ax, %gs
movw %ax, %es
cmpb $0, 0x1be
je 1f
movl 0x1be + 8, %eax
movl %eax, first_sector
jmp load
1: cmpb $0, 0x1ce
je 1f
movl 0x1ce + 8, %eax
movl %eax, first_sector
jmp load
1: cmpb $0, 0x1de
je 1f
movl 0x1de + 8, %eax
movl %eax, first_sector
jmp load
1: cmpb $0, 0x1ee
je 1f
movl 0x1ee + 8, %eax
movl %eax, first_sector
jmp load
1: movw $msg_noact, %si
call bios_puts
jmp halt
load:
movl first_sector, %eax
movl %eax, lba_packet_block
movb $0x42, %ah
movb $0x80, %dl
movw $lba_packet, %si
int $0x13
jc load_chs
movb $0x80, %dl
ljmp $0x7c0, $0
lba_packet:
.byte 16
.byte 0
.byte 1
.byte 0
.word 0, 0x7c0
lba_packet_block:
.quad 0
load_chs:
movb $0x08, %ah
movb $0x80, %dl
int $0x13
jc error
movb %ch, nr_cyl
movb %cl, nr_sect
andb $63, nr_sect
shrb $6, %cl
movb %cl, nr_cyl + 1
movb %dh, nr_head
incw nr_cyl
incw nr_head
movl first_sector, %eax
movl nr_sect, %edx
divl %edx
movl %edx, sect_i
movl nr_head, %edx
divl %edx
movl %edx, head_i
movl %eax, cyl_i
movw $0x7c0, %ax
movw %ax, %es
movw $0, %bx
movw $0x0201, %ax
movb cyl_i, %ch
movb sect_i, %cl
incb %cl
movb head_i, %dh
movb $0x80, %dl
int $0x13
jc error
movb $0x80, %dl
ljmp $0x7c0, $0
error:
movw $msg_ioerr, %si
call bios_puts
halt: movw $msg_halt, %si
call bios_puts
1: hlt
jmp 1b
bios_puts:
movw $0x0007, %bx
bios_puts_loop:
lodsb
cmpb $0x00,%al
jz bios_puts_end
movb $0x0e, %ah
int $0x10
jmp bios_puts_loop
bios_puts_end:
ret
cyl_i: .long 0
head_i: .long 0
sect_i: .long 0
nr_cyl: .long 0
nr_head: .long 0
nr_sect: .long 0
first_sector: .long 0
msg_noact: .asciz "No active partitions.\r\n"
msg_ioerr: .asciz "Disk error.\r\n"
msg_halt: .asciz "System halted.\r\n"