175 lines
4.2 KiB
ArmAsm
175 lines
4.2 KiB
ArmAsm
|
# Copyright (c) KATO Takenori, 1999, 2000.
|
||
|
|
#
|
||
|
|
# All rights reserved. Unpublished rights reserved under the copyright
|
||
|
|
# laws of Japan.
|
||
|
|
#
|
||
|
|
# 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 as
|
||
|
|
# the first lines of this file unmodified.
|
||
|
|
# 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 AUTHOR ``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 AUTHOR 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.
|
||
|
|
#
|
||
|
|
# $FreeBSD$
|
||
|
|
#
|
||
|
|
|
||
|
|
.code16
|
||
|
|
|
||
|
|
.text
|
||
|
|
.global boot
|
||
|
|
#
|
||
|
|
# Read bootstrap program and jump to it.
|
||
|
|
#
|
||
|
|
boot:
|
||
|
|
# Step 1: Save parameters
|
||
|
|
movw curdevice, %si
|
||
|
|
movb daua(%si), %al
|
||
|
|
movb %al, b_daua
|
||
|
|
shlw %si
|
||
|
|
movw secsize(%si), %ax
|
||
|
|
movw %ax, b_secsize
|
||
|
|
|
||
|
|
movw curpartition, %si
|
||
|
|
movb partnum(%si), %al # %al = real partition number
|
||
|
|
xorb %ah, %ah
|
||
|
|
movw %ax, b_partn # save real parttion number
|
||
|
|
movb $5, %cl
|
||
|
|
shlw %cl, %si # %si = offset to parttable
|
||
|
|
addw $4, %si
|
||
|
|
movb parttable(%si), %al # IPLS
|
||
|
|
movb %al, b_sector
|
||
|
|
incw %si
|
||
|
|
movb parttable(%si), %al # IPLH
|
||
|
|
movb %al, b_head
|
||
|
|
incw %si # IPLC
|
||
|
|
movw parttable(%si), %ax
|
||
|
|
movw %ax, b_cylinder
|
||
|
|
|
||
|
|
# Step 2: Calculate egment address of bootstrap routine
|
||
|
|
movw $0x1d00, %ax
|
||
|
|
movw b_secsize, %cx
|
||
|
|
shrw %cx
|
||
|
|
shrw %cx
|
||
|
|
subw %cx, %ax
|
||
|
|
subw $0x100, %ax
|
||
|
|
movw %ax, b_bootseg
|
||
|
|
|
||
|
|
# Step 3: Read bootstrap code
|
||
|
|
movb $6, %ah
|
||
|
|
movb b_daua, %al
|
||
|
|
movw b_secsize, %bx
|
||
|
|
shlw %bx # 2 sectors
|
||
|
|
movw b_cylinder, %cx
|
||
|
|
movb b_head, %dh
|
||
|
|
movb b_sector, %dl
|
||
|
|
movw b_bootseg, %es
|
||
|
|
xorw %bp, %bp
|
||
|
|
int $0x1b
|
||
|
|
jc boot_error
|
||
|
|
|
||
|
|
# Step 4: Set DA/UA into BIOS work area
|
||
|
|
xorw %ax, %ax
|
||
|
|
movw %ax, %es
|
||
|
|
movw $0x584, %bx # DISK_BOOT
|
||
|
|
movb b_daua, %dl
|
||
|
|
call write_biosparam
|
||
|
|
|
||
|
|
call sc_clean
|
||
|
|
# Step 5: Set registers
|
||
|
|
# %ah: 00
|
||
|
|
# %al: DA/UA
|
||
|
|
# %bx: Sector size * 2
|
||
|
|
# %cx: cylinder number of boot partition
|
||
|
|
# %si: pointer to partition table
|
||
|
|
movw b_partn, %ax
|
||
|
|
movb $10, %cl
|
||
|
|
shl %cl, %ax # %ax = partition number * 32 * 32
|
||
|
|
addw b_secsize, %ax
|
||
|
|
movw %ax, %si # %si = pointer to partition table
|
||
|
|
movw b_cylinder, %cx # %cx = cylinder
|
||
|
|
movb b_head, %dh # %dh = head
|
||
|
|
movb b_sector, %dl # %dl = sector
|
||
|
|
movw b_bootseg, %es # %es = boot segment
|
||
|
|
movb b_daua, %al # %al = DA/UA
|
||
|
|
movw b_secsize, %bx
|
||
|
|
shlw %bx # %bx = sector size * 2
|
||
|
|
cli
|
||
|
|
movw %cs:iniss, %ss # Restore stack pointer
|
||
|
|
movw %cs:inisp, %sp
|
||
|
|
push %es # Boot segment
|
||
|
|
xorw %bp, %bp
|
||
|
|
push %bp # 0
|
||
|
|
movw %ax, %di # Save %ax
|
||
|
|
xorw %ax, %ax
|
||
|
|
movw %ax, %ds # %ds = 0
|
||
|
|
movw %di, %ax # Restore %ax
|
||
|
|
xorb %ah, %ah # %di = 0
|
||
|
|
xorw %di, %di # %di = 0
|
||
|
|
sti
|
||
|
|
|
||
|
|
# Jump to bootstrap code
|
||
|
|
lret
|
||
|
|
# NOTREACHED
|
||
|
|
|
||
|
|
boot_error:
|
||
|
|
ret
|
||
|
|
|
||
|
|
#
|
||
|
|
# Try to boot from default partition.
|
||
|
|
#
|
||
|
|
.global trydefault
|
||
|
|
trydefault:
|
||
|
|
movw ndevice, %cx
|
||
|
|
xorw %si, %si
|
||
|
|
trydefault_loop:
|
||
|
|
movw %si, curdevice
|
||
|
|
push %cx
|
||
|
|
push %si
|
||
|
|
call read_ipl
|
||
|
|
pop %si
|
||
|
|
pop %cx
|
||
|
|
cmpb $0x80, defpartflag
|
||
|
|
jne nodefpart
|
||
|
|
# Default partition is defined.
|
||
|
|
push %cx
|
||
|
|
movw npartition, %cx
|
||
|
|
srch_part:
|
||
|
|
movw %cx, %bx
|
||
|
|
decw %bx
|
||
|
|
movb defpartnum, %al # %al = real partition number
|
||
|
|
cmpb partnum(%bx), %al
|
||
|
|
jne not_match
|
||
|
|
movw %bx, curpartition # Store partition number
|
||
|
|
call boot
|
||
|
|
not_match:
|
||
|
|
loop srch_part
|
||
|
|
pop %cx
|
||
|
|
nodefpart:
|
||
|
|
incw %si
|
||
|
|
loop trydefault_loop
|
||
|
|
ret
|
||
|
|
|
||
|
|
.data
|
||
|
|
b_daua: .byte 0 # DA/UA
|
||
|
|
b_head: .byte 0 # SYSH
|
||
|
|
b_sector: .byte 0 # SYSS
|
||
|
|
b_cylinder: .word 0 # SYSC
|
||
|
|
b_bootseg: .word 0
|
||
|
|
b_secsize: .word 0
|
||
|
|
b_partn: .word 0 # Real partition number
|