mirror of
https://github.com/xcat2/xNBA.git
synced 2024-12-15 15:51:44 +00:00
302 lines
6.7 KiB
ArmAsm
302 lines
6.7 KiB
ArmAsm
#warning "Needs fixing up for gpxe"
|
|
|
|
#if 0
|
|
|
|
/****************************************************************\
|
|
|
|
hdprefix.S Copyright (C) 2005 Per Dalgas Jakobsen
|
|
|
|
This code has been inspired/derived by the OSLoader by Vladislav Aleksandrov.
|
|
http://www.programmersheaven.com/zone5/cat469/40546.htm.
|
|
|
|
This software may be used and distributed according to the terms
|
|
of the GNU Public License (GPL), incorporated herein by reference.
|
|
|
|
hdprefix.S is loaded at 0x0000:0x7c00 by the bios-startup routines.
|
|
|
|
Actions performed by hdprefix:
|
|
1) Load the MBR to LOADSEG:0
|
|
2) Check which partition is active (or try first partition if none active)
|
|
3) Check wether LBA is supported.
|
|
3a) LBA
|
|
3a1) Load PAYLOAD_SECTS sectors from chosen partition to LOADSEG:0
|
|
3b) CHS (standard)
|
|
3b1) Load PAYLOAD_SECTS sectors from chosen partition to LOADSEG:0
|
|
4) Check loaded bootsector for BOOTMAGIC code.
|
|
5) Jump to payload LOADSEG:ENTRYPOINT.
|
|
|
|
Output with failure points (!#):
|
|
---
|
|
Loading (!1)partition #
|
|
Std. BIOS(!2) | Ext. BIOS(!3)
|
|
Booting...(!4)
|
|
(!5)
|
|
---
|
|
|
|
!1: Failed to load MBR with Int13,ah=2.
|
|
!2: Failed to load bootrecord+payload with Int13,ah=2.
|
|
!3: Failed to load bootrecord+payload with Int13,ah=42.
|
|
!4: Invalid BOOTMAGIC in loaded bootrecord.
|
|
!5: Jumping to payload.
|
|
|
|
\*****************************************************************/
|
|
|
|
.equ BOOTSEG, 0x07c0
|
|
.equ LOADSEG, 0x1000
|
|
.equ ENTRYPOINT, _start
|
|
|
|
.equ BOOTMAGIC, 0x0aa55
|
|
|
|
.equ partition_table, 0x1be
|
|
.equ partition_rec_size, 0x10
|
|
|
|
.equ boot_ind, 0 /* 80h=active */
|
|
.equ start_head, 1
|
|
.equ start_sector, 2 /* bits 0-5 */
|
|
.equ start_cyl, 3 /* bits 8,9 in bits 6,7 of sector */
|
|
.equ os_ind, 4 /* os indicator */
|
|
.equ end_head, 5
|
|
.equ end_sector, 6 /* bits 0-5 */
|
|
.equ end_track, 7 /* bits 8,9 in bits 6,7 of sector */
|
|
.equ nsect, 8 /* sectors preceding partition */
|
|
.equ lenght, 0x0c /* length of partition in sectors */
|
|
|
|
/-------------------------------------------------------------
|
|
|
|
.arch i386
|
|
.text
|
|
.section ".prefix", "ax", @progbits
|
|
.code16
|
|
|
|
bootstart:
|
|
jmp $BOOTSEG,$_go /* reload cs:ip */
|
|
|
|
|
|
/****************************************************************/
|
|
/* support routines. */
|
|
/*--------------------------------------------------------------*/
|
|
_failed:
|
|
movw $BOOTSEG,%ax
|
|
movw %ax,%ds
|
|
movw $_failed_msg_end-_failed_msg,%cx
|
|
movw $_failed_msg,%si
|
|
call _print_str
|
|
|
|
/* stop execution - should probably have option to auto-reboot after delay. */
|
|
_failed_loop:
|
|
jmp _failed_loop
|
|
|
|
/*--------------------------------------------------------------*/
|
|
_print_str:
|
|
/* cx = count, ds:si = string. */
|
|
movw $0x0007,%bx
|
|
movb $0x0e,%ah
|
|
_print_loop:
|
|
lodsb
|
|
int $0x10
|
|
loop _print_loop
|
|
ret
|
|
|
|
/*--------------------------------------------------------------*/
|
|
_print_char:
|
|
/* al = char. */
|
|
movw $0x0007,%bx
|
|
movb $0x0e,%ah
|
|
int $0x10
|
|
ret
|
|
|
|
/*--------------------------------------------------------------*/
|
|
_print_nl:
|
|
/* - */
|
|
movb $0x0d,%al
|
|
call _print_char
|
|
movb $0x0a,%al
|
|
call _print_char
|
|
ret
|
|
|
|
/*--------------------------------------------------------------*/
|
|
_print_hex:
|
|
/* dx = value */
|
|
movb $0x0e,%ah /* write char, tty mode */
|
|
movw $0x0007,%bx /* page 0, attribute 7 (normal) */
|
|
call _print_digit
|
|
call _print_digit
|
|
call _print_digit
|
|
/* fall through */
|
|
_print_digit:
|
|
rolw $4,%dx /* rotate so that lowest 4 bits are used */
|
|
movb $0x0f,%al /* mask for nibble */
|
|
andb %dl,%al
|
|
addb $0x90,%al /* convert al to ascii hex (four instructions) */
|
|
daa
|
|
adcb $0x40,%al
|
|
daa
|
|
int $0x10
|
|
ret
|
|
|
|
/****************************************************************/
|
|
|
|
|
|
_go:
|
|
cli
|
|
movw $BOOTSEG,%ax
|
|
movw %ax,%ds
|
|
movw %ax,%ss
|
|
movw $0x2000,%sp /* good large stack. */
|
|
sti
|
|
cld
|
|
movw $LOADSEG,%ax
|
|
movw %ax,%es
|
|
|
|
movw $_load_msg_end-_load_msg,%cx
|
|
movw $_load_msg,%si
|
|
call _print_str
|
|
|
|
/*--- load MBR so we can use its partition table. ---*/
|
|
xorw %bx,%bx
|
|
movw $0x0001,%cx /* chs: 0,0,1 */
|
|
movb %bh,%dh /* - */
|
|
movb $0x80,%dl
|
|
movw $0x0201,%ax /* read one sector (MBR) */
|
|
int $0x13
|
|
jc _failed
|
|
|
|
/*--- find the active partition ---*/
|
|
movw $_part_msg_end-_part_msg,%cx
|
|
movw $_part_msg,%si
|
|
call _print_str
|
|
|
|
movw $partition_table,%di
|
|
movw $4,%cx
|
|
_partition_loop:
|
|
cmpb $0x80,%es:(%di) /* active? */
|
|
je _partition_found
|
|
addw $partition_rec_size,%di
|
|
loop _partition_loop
|
|
|
|
/*- no partitions marked active - use 1. partition. */
|
|
movw $partition_table,%di
|
|
movw $4,%cx
|
|
|
|
_partition_found:
|
|
movb $'5',%al /* convert to ascii */
|
|
subb %cl,%al
|
|
call _print_char
|
|
call _print_nl
|
|
|
|
/*--- check for lba support ---*/
|
|
movw $0x55aa,%bx
|
|
movb $0x80,%dl
|
|
movb $0x41,%ah
|
|
int $0x13
|
|
jc __bios
|
|
cmpw $0x0aa55,%bx
|
|
jnz __bios
|
|
testb $1,%cl
|
|
jz __bios
|
|
|
|
/*--- use lba bios calls to read sectors ---*/
|
|
_lba:
|
|
movw $_extbios_msg_end-_extbios_msg,%cx
|
|
movw $_extbios_msg,%si
|
|
call _print_str
|
|
|
|
movw %es:nsect(%di),%ax
|
|
movw %ax,_bios_lba_low
|
|
movw %es:nsect+2(%di),%ax
|
|
movw %ax,_bios_lba_high
|
|
movb $0x80,%dl
|
|
movw $_disk_address_packet,%si
|
|
movw $0x4200,%ax /* read */
|
|
int $0x13
|
|
jc _failed
|
|
jmp __loaded
|
|
|
|
/*--- use standard bios calls to read sectors ---*/
|
|
__bios:
|
|
movw $_stdbios_msg_end-_stdbios_msg,%cx
|
|
movw $_stdbios_msg,%si
|
|
call _print_str
|
|
|
|
movw _disk_address_packet+2(,1),%ax /* only low byte is used. */
|
|
xorw %bx,%bx
|
|
movw %es:start_sector(%di),%cx
|
|
movb %es:start_head(%di),%dh
|
|
movb $0x80,%dl
|
|
movb $0x02,%ah
|
|
int $0x13
|
|
jc _failed
|
|
|
|
__loaded:
|
|
movw $_boot_msg_end-_boot_msg,%cx
|
|
movw $_boot_msg,%si
|
|
call _print_str
|
|
|
|
/* check if it has a valid bootrecord. */
|
|
cmpw $BOOTMAGIC,%es:510(,1)
|
|
jne _failed
|
|
call _print_nl
|
|
|
|
/* call the payload. */
|
|
pushl $0 /* No parameters to preserve for exit path */
|
|
pushw $0 /* Use prefix exit path mechanism */
|
|
jmp $LOADSEG,$ENTRYPOINT
|
|
|
|
.section ".text16", "ax", @progbits
|
|
.globl prefix_exit
|
|
prefix_exit:
|
|
int $0x19 /* should try to boot machine */
|
|
.globl prefix_exit_end
|
|
prefix_exit_end:
|
|
.previous
|
|
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
_load_msg: .ascii "Loading "
|
|
_load_msg_end:
|
|
_part_msg: .ascii "partition "
|
|
_part_msg_end:
|
|
_boot_msg: .ascii "Booting..."
|
|
_boot_msg_end:
|
|
_stdbios_msg: .ascii "Std. BIOS\r\n"
|
|
_stdbios_msg_end:
|
|
_extbios_msg: .ascii "Ext. BIOS\r\n"
|
|
_extbios_msg_end:
|
|
_failed_msg: .ascii "FAILED!!!\r\n"
|
|
_failed_msg_end:
|
|
|
|
|
|
/*--------------------------------------------------------------*/
|
|
|
|
_disk_address_packet:
|
|
.byte 0x10 /* size of the packet */
|
|
.byte 0 /* reserved */
|
|
.word _verbatim_size_sct /* number of sectors to read */
|
|
.word 0x0000 /* offset */
|
|
.word LOADSEG /* segment of buffer */
|
|
_bios_lba_low: .word 0
|
|
_bios_lba_high: .word 0
|
|
.word 0
|
|
.word 0
|
|
|
|
.rept 32
|
|
.byte 0
|
|
.endr
|
|
|
|
|
|
/*--- Partition table ------------------------------------------*/
|
|
|
|
.org 446, 0
|
|
.rept 64
|
|
.byte 0
|
|
.endr
|
|
|
|
|
|
/*--- Magic code -----------------------------------------------*/
|
|
.org 510, 0
|
|
.word BOOTMAGIC
|
|
|
|
/*** END ********************************************************/
|
|
#endif
|