253 lines
6.9 KiB
ArmAsm
253 lines
6.9 KiB
ArmAsm
#
|
|
# Copyright (c) 1998 Robert Nordier
|
|
# All rights reserved.
|
|
#
|
|
# Redistribution and use in source and binary forms are freely
|
|
# permitted provided that the above copyright notice and this
|
|
# paragraph and the following disclaimer are duplicated in all
|
|
# such forms.
|
|
#
|
|
# This software is provided "AS IS" and without any express or
|
|
# implied warranties, including, without limitation, the implied
|
|
# warranties of merchantability and fitness for a particular
|
|
# purpose.
|
|
#
|
|
|
|
# $Id: boot0.s,v 1.5 1998/11/29 14:09:00 rnordier Exp $
|
|
|
|
# A 512-byte boot manager.
|
|
|
|
.set NHRDRV,0x475 # Number of hard drives
|
|
.set ORIGIN,0x600 # Execution address
|
|
.set DSKPKT,0x800 # Disk packet
|
|
.set FAKE,0x810 # Partition entry
|
|
.set LOAD,0x7c00 # Load address
|
|
|
|
.set PRT_OFF,0x1be # Partition table
|
|
|
|
.set TBL0SZ,0x3 # Table 0 size
|
|
.set TBL1SZ,0xa # Table 1 size
|
|
|
|
.set MAGIC,0xaa55 # Magic: bootable
|
|
|
|
.set KEY_ENTER,0x1c # Enter key scan code
|
|
.set KEY_F1,0x3b # F1 key scan code
|
|
|
|
.set _NXTDRV,-0x47 # Drive number
|
|
.set _OPT,-0x46 # Default option
|
|
.set _FLAGS,-0x45 # Flags
|
|
.set _TICKS,-0x44 # Timeout ticks
|
|
.set _FAKE,0x10 # Fake partition entry
|
|
.set _MNUOPT,0x1c # Menu options
|
|
|
|
.globl start # Entry point
|
|
|
|
start: cld # String ops inc
|
|
xorl %eax,%eax # Zero
|
|
movl %eax,%es # Address
|
|
movl %eax,%ds # data
|
|
movl %eax,%ss # Set up
|
|
movwir(LOAD,_sp) # stack
|
|
movl %esp,%esi # Source
|
|
movwir(start,_di) # Destination
|
|
movwir(0x100,_cx) # Word count
|
|
rep # Relocate
|
|
movsl # code
|
|
movl %edi,%ebp # Address variables
|
|
movb $0x10,%cl # Words to clear
|
|
rep # Zero
|
|
stosl # them
|
|
incb1(-0xe,_di_) # Sector number
|
|
jmpnwi(main-LOAD+ORIGIN) # To relocated code
|
|
|
|
main: movbr1(_dl,_FAKE,_bp_) # Save drive number
|
|
callwi(putn) # To new line
|
|
movwir(partbl,_bx) # Partition table
|
|
xorl %edx,%edx # Item
|
|
main.1: movbr0(_dh,_bx_) # Mark inactive
|
|
movb1r(0x4,_bx_,_al) # Load type
|
|
movwir(tables,_di) # Lookup tables
|
|
movb $TBL0SZ,%cl # Entries
|
|
repne # Exclude
|
|
scasb # partition?
|
|
je main.3 # Yes
|
|
movb $TBL1SZ,%cl # Entries
|
|
repne # Known
|
|
scasb # type?
|
|
jne main.2 # No
|
|
addwir(TBL1SZ,_di) # Adjust
|
|
main.2: movb0r(_di_,_cl) # Partition
|
|
addl %ecx,%edi # description
|
|
callwi(putx) # Display it
|
|
main.3: addwir(0x10,_bx) # Next entry
|
|
incl %edx # Next item
|
|
cmpb $0x4,%dl # Done?
|
|
jb main.1 # No
|
|
movb1r(_FAKE,_bp_,_al) # Drive number
|
|
subb $0x80-0x1,%al # Does next
|
|
cmpbmr(NHRDRV,_al) # drive exist?
|
|
jb main.4 # Yes
|
|
decb %al # Already drive 0?
|
|
jz main.5 # Yes
|
|
xorb %al,%al # Drive 0
|
|
main.4: addb $'0'|0x80,%al # Save
|
|
movbr1(_al,_NXTDRV,_bp_) # it
|
|
movwir(drive,_di) # Display
|
|
callwi(putx) # item
|
|
main.5: movwir(prompt,_si) # Display
|
|
callwi(putstr) # prompt
|
|
movb1r(_OPT,_bp_,_dl) # Display
|
|
decl %esi # default
|
|
callwi(putkey) # key
|
|
xorb %ah,%ah # BIOS: Get
|
|
int $0x1a # system time
|
|
movl %edx,%edi # Save ticks
|
|
main.6: movb $0x1,%ah # BIOS: Check
|
|
int $0x16 # for keypress
|
|
jnz main.9 # Have one
|
|
xorb %ah,%ah # BIOS: Get
|
|
int $0x1a # system time
|
|
subl %edi,%edx # Elapsed time
|
|
cmpw1r(_TICKS,_bp_,_dx) # Timeout?
|
|
jb main.6 # No
|
|
main.7: movb1r(_OPT,_bp_,_al) # Load default
|
|
jmp main.10 # Join common code
|
|
main.8: movb $0x7,%al # Signal
|
|
callwi(putchr) # error
|
|
main.9: xorb %ah,%ah # BIOS: Get
|
|
int $0x16 # keypress
|
|
movb %ah,%al # Scan code
|
|
cmpb $KEY_ENTER,%al # Enter pressed?
|
|
je main.7 # No
|
|
subb $KEY_F1,%al # Less F1 scan code
|
|
cmpb $0x4,%al # F1..F5?
|
|
ja main.8 # No
|
|
main.10: cwtl # Option
|
|
btwr1(_ax,_MNUOPT,_bp_) # enabled?
|
|
jnc main.8 # No
|
|
movwir(FAKE,_si) # Partition entry
|
|
movb1r(_NXTDRV,_bp_,_dl) # Next drive
|
|
subb $'0',%dl # number
|
|
cmpb $0x4,%al # F5 pressed?
|
|
je main.11 # Yes
|
|
movb0r(_si_,_dl) # Drive number
|
|
movbr1(_al,_OPT,_bp_) # Save option
|
|
shlb $0x4,%al # Point to
|
|
addwia(partbl) # partition
|
|
xchgl %esi,%eax # entry
|
|
tstbi1(0x40,_FLAGS,_bp_) # No updates?
|
|
jnz main.11 # Yes
|
|
movbi0(0x80,_si_) # Flag active
|
|
pushl %esi # Save
|
|
xchgl %esi,%eax # Fake partition entry
|
|
movwir(start,_bx) # Data to write
|
|
movwir(0x301,_ax) # Write sector
|
|
callwi(intx13) # to disk
|
|
popl %esi # Restore
|
|
main.11: movwir(LOAD,_bx) # Address for read
|
|
movwir(0x201,_ax) # Read sector
|
|
callwi(intx13) # from disk
|
|
jc main.8 # If error
|
|
cmpwi2(MAGIC,0x1fe,_bx_) # Bootable?
|
|
jne main.8 # No
|
|
movwir(crlf,_si) # Leave some
|
|
callwi(puts) # space
|
|
jmp *%ebx # Invoke bootstrap
|
|
|
|
# Display routines
|
|
|
|
putkey: movb $'F',%al # Display
|
|
callwi(putchr) # 'F'
|
|
movb $'1',%al # Prepare
|
|
addb %dl,%al # digit
|
|
jmp putstr.1 # Display the rest
|
|
|
|
putx: btswr1(_dx,_MNUOPT,_bp_) # Enable menu option
|
|
movwir(item,_si) # Display
|
|
callwi(putkey) # key
|
|
movl %edi,%esi # Display the rest
|
|
|
|
puts: callwi(putstr) # Display string
|
|
|
|
putn: movwir(crlf,_si) # To next line
|
|
|
|
putstr: lodsb # Get byte
|
|
testb $0x80,%al # End of string?
|
|
jnz putstr.2 # Yes
|
|
putstr.1: callwi(putchr) # Display char
|
|
jmp putstr # Continue
|
|
putstr.2: andb $~0x80,%al # Clear MSB
|
|
|
|
putchr: pushl %ebx # Save
|
|
movwir(0x7,_bx) # Page:attribute
|
|
movb $0xe,%ah # BIOS: Display
|
|
int $0x10 # character
|
|
popl %ebx # Restore
|
|
ret # To caller
|
|
|
|
# Disk I/O routine
|
|
|
|
intx13: cli # Disable interrupts
|
|
movb1r(0x1,_si_,_dh) # Load head
|
|
movw1r(0x2,_si_,_cx) # Load cylinder:sector
|
|
o16 # Load
|
|
movw1r(0x8,_si_,_di) # offset
|
|
movwir(DSKPKT,_si) # Packet pointer
|
|
movbi0(0x10,_si_) # Packet size
|
|
movbr1(_al,0x2,_si_) # Block count
|
|
movwr1(_bx,0x4,_si_) # Transfer
|
|
movws1(_es,0x6,_si_) # buffer
|
|
o16 # LBA
|
|
movwr1(_di,0x8,_si_) # address
|
|
sti # Enable interrupts
|
|
tstbi1(0x80,_FLAGS,_bp_) # Use packet interface?
|
|
jz intx13.1 # No
|
|
orb $0x40,%ah # Use disk packet
|
|
decl %eax # Verify off
|
|
intx13.1: int $0x13 # BIOS: Disk I/O
|
|
ret # To caller
|
|
|
|
# Menu strings
|
|
|
|
item: .ascii " "; .byte ' '|0x80
|
|
prompt: .ascii "\nDefault:"; .byte ' '|0x80
|
|
crlf: .ascii "\r"; .byte '\n'|0x80
|
|
|
|
# Partition type tables
|
|
|
|
tables:
|
|
.byte 0x0, 0x5, 0xf
|
|
|
|
.byte 0x1, 0x4, 0x6, 0xb, 0xc, 0xe, 0x63, 0x83
|
|
.byte 0xa5, 0xa6
|
|
|
|
.byte os_misc-. # Unknown
|
|
.byte os_dos-. # DOS
|
|
.byte os_dos-. # DOS
|
|
.byte os_dos-. # DOS
|
|
.byte os_dos-. # Windows
|
|
.byte os_dos-. # Windows
|
|
.byte os_dos-. # Windows
|
|
.byte os_unix-. # UNIX
|
|
.byte os_linux-. # Linux
|
|
.byte os_freebsd-. # FreeBSD
|
|
.byte os_bsd-. # OpenBSD
|
|
|
|
os_misc: .ascii "?"; .byte '?'|0x80
|
|
os_dos: .ascii "DO"; .byte 'S'|0x80
|
|
os_unix: .ascii "UNI"; .byte 'X'|0x80
|
|
os_linux: .ascii "Linu"; .byte 'x'|0x80
|
|
os_freebsd: .ascii "Free"
|
|
os_bsd: .ascii "BS"; .byte 'D'|0x80
|
|
|
|
.org PRT_OFF-0xb,0x90
|
|
|
|
drive: .ascii "Drive "
|
|
nxtdrv: .byte 0x0 # Next drive number
|
|
opt: .byte 0x0 # Option
|
|
flags: .byte FLAGS # Flags
|
|
ticks: .word TICKS # Delay
|
|
|
|
partbl: .fill 0x40,0x1,0x0 # Partition table
|
|
.word MAGIC # Magic number
|