mirror of https://github.com/acidanthera/audk.git
290 lines
12 KiB
ArmAsm
290 lines
12 KiB
ArmAsm
#------------------------------------------------------------------------------
|
|
#*
|
|
#* Copyright 2006 - 2007, Intel Corporation
|
|
#* All rights reserved. This program and the accompanying materials
|
|
#* are licensed and made available under the terms and conditions of the BSD License
|
|
#* which accompanies this distribution. The full text of the license may be found at
|
|
#* http://opensource.org/licenses/bsd-license.php
|
|
#*
|
|
#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
|
|
#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
|
|
#*
|
|
#* bootsect.asm
|
|
#*
|
|
#* Abstract:
|
|
#*
|
|
#------------------------------------------------------------------------------
|
|
|
|
#.MODEL small
|
|
.stack:
|
|
.486p:
|
|
.code:
|
|
|
|
.equ FAT_DIRECTORY_ENTRY_SIZE, 0x020
|
|
.equ FAT_DIRECTORY_ENTRY_SHIFT, 5
|
|
.equ BLOCK_SIZE, 0x0200
|
|
.equ BLOCK_MASK, 0x01ff
|
|
.equ BLOCK_SHIFT, 9
|
|
# "EFILDR_____"
|
|
.equ LOADER_FILENAME_PART1, 0x04c494645 # "EFIL"
|
|
.equ LOADER_FILENAME_PART2, 0x020205244 # "DR__"
|
|
.equ LOADER_FILENAME_PART3, 0x020202020 # "____"
|
|
|
|
.org 0x0
|
|
Ia32Jump:
|
|
jmp BootSectorEntryPoint # JMP inst - 3 bytes
|
|
nop
|
|
|
|
OemId: .ascii "INTEL " # OemId - 8 bytes
|
|
# BPB data below will be fixed by tool
|
|
SectorSize: .word 0 # Sector Size - 16 bits
|
|
SectorsPerCluster: .byte 0 # Sector Per Cluster - 8 bits
|
|
ReservedSectors: .word 0 # Reserved Sectors - 16 bits
|
|
NoFats: .byte 0 # Number of FATs - 8 bits
|
|
RootEntries: .word 0 # Root Entries - 16 bits
|
|
Sectors: .word 0 # Number of Sectors - 16 bits
|
|
Media: .byte 0 # Media - 8 bits - ignored
|
|
SectorsPerFat: .word 0 # Sectors Per FAT - 16 bits
|
|
SectorsPerTrack: .word 0 # Sectors Per Track - 16 bits - ignored
|
|
Heads: .word 0 # Heads - 16 bits - ignored
|
|
HiddenSectors: .long 0 # Hidden Sectors - 32 bits - ignored
|
|
LargeSectors: .long 0 # Large Sectors - 32 bits
|
|
PhysicalDrive: .byte 0 # PhysicalDriveNumber - 8 bits - ignored
|
|
CurrentHead: .byte 0 # Current Head - 8 bits
|
|
Signature: .byte 0 # Signature - 8 bits - ignored
|
|
VolId: .ascii " " # Volume Serial Number- 4 bytes
|
|
FatLabel: .ascii " " # Label - 11 bytes
|
|
SystemId: .ascii "FAT12 " # SystemId - 8 bytes
|
|
|
|
BootSectorEntryPoint:
|
|
#ASSUME ds:@code
|
|
#ASSUME ss:@code
|
|
|
|
# ****************************************************************************
|
|
# Start Print
|
|
# ****************************************************************************
|
|
leaw %cs:StartString, %si
|
|
call PrintString
|
|
|
|
# ****************************************************************************
|
|
# Print over
|
|
# ****************************************************************************
|
|
|
|
movw %cs, %ax # ax = 0
|
|
movw %ax, %ss # ss = 0
|
|
addw $0x1000, %ax
|
|
movw %ax, %ds
|
|
|
|
movw $0x7c00, %sp # sp = 0x7c00
|
|
movw %sp, %bp # bp = 0x7c00
|
|
|
|
movb $8, %ah # ah = 8 - Get Drive Parameters Function
|
|
movb %dl, PhysicalDrive(%bp) # BBS defines that BIOS would pass the booting driver number to the loader through DL
|
|
int $0x13 # Get Drive Parameters
|
|
xorw %ax, %ax # ax = 0
|
|
movb %dh, %al # al = dh
|
|
incb %al # MaxHead = al + 1
|
|
pushw %ax # 0000:7bfe = MaxHead
|
|
movb %cl, %al # al = cl
|
|
andb $0x3f, %al # MaxSector = al & 0x3f
|
|
pushw %ax # 0000:7bfc = MaxSector
|
|
|
|
cmpw $0xaa55, SectorSignature(%bp) # Verify Boot Sector Signature
|
|
jne BadBootSector
|
|
movw RootEntries(%bp), %cx # cx = RootEntries
|
|
shlw $FAT_DIRECTORY_ENTRY_SHIFT, %cx # cx = cx * 32 = cx * sizeof(FAT_DIRECTORY_ENTRY) = Size of Root Directory in bytes
|
|
movw %cx, %bx # bx = size of the Root Directory in bytes
|
|
andw $BLOCK_MASK, %bx # See if it is an even number of sectors long
|
|
jne BadBootSector # If is isn't, then the boot sector is bad.
|
|
movw %cx, %bx # bx = size of the Root Directory in bytes
|
|
shrw $BLOCK_SHIFT, %bx # bx = size of Root Directory in sectors
|
|
movb NoFats(%bp), %al # al = NoFats
|
|
xorb %ah, %ah # ah = 0 ==> ax = NoFats
|
|
mulw SectorsPerFat(%bp) # ax = NoFats * SectorsPerFat
|
|
addw ReservedSectors(%bp), %ax # ax = NoFats * SectorsPerFat + ReservedSectors = RootLBA
|
|
pushw %ds
|
|
popw %es
|
|
xorw %di, %di # Store directory in es:di = 1000:0000
|
|
call ReadBlocks # Read entire Root Directory
|
|
addw %bx, %ax # ax = NoFats * SectorsPerFat + ReservedSectors + RootDirSectors = FirstClusterLBA (FirstDataSector)
|
|
movw %ax, (%bp) # Save FirstClusterLBA (FirstDataSector) for later use
|
|
|
|
# dx - variable storage (initial value is 0)
|
|
# bx - loader (initial value is 0)
|
|
xorw %dx, %dx
|
|
xorw %bx, %bx
|
|
|
|
FindEFILDR:
|
|
cmpl $LOADER_FILENAME_PART1, (%di) # Compare to "EFIL"
|
|
jne FindVARSTORE
|
|
cmpl $LOADER_FILENAME_PART2, 4(%di)
|
|
jne FindVARSTORE
|
|
cmpl $LOADER_FILENAME_PART3, 7(%di)
|
|
jne FindVARSTORE
|
|
movw 26(%di), %bx # bx = Start Cluster for EFILDR <----------------------------------
|
|
testw %dx, %dx
|
|
je FindNext # Efivar.bin is not loaded
|
|
jmp FoundAll
|
|
|
|
FindVARSTORE:
|
|
## if the file is not loader file, see if it's "EFIVAR BIN"
|
|
cmpl $0x56494645, (%di) # Compare to "EFIV"
|
|
jne FindNext
|
|
cmpl $0x20205241, 4(%di) # Compare to "AR "
|
|
jne FindNext
|
|
cmpl $0x4e494220, 7(%di) # Compare to " BIN"
|
|
jne FindNext
|
|
movw %di, %dx # dx = Offset of Start Cluster for Efivar.bin <---------------------
|
|
addw $26, %dx
|
|
testw %bx, %bx
|
|
je FindNext # Efildr is not loaded
|
|
jmp FoundAll
|
|
|
|
FindNext:
|
|
# go to next find
|
|
addw $FAT_DIRECTORY_ENTRY_SIZE, %di # Increment di
|
|
subw $FAT_DIRECTORY_ENTRY_SIZE, %cx # Decrement cx
|
|
# TODO: jump to FindVarStore if ...
|
|
jne FindEFILDR
|
|
jmp NotFoundAll
|
|
|
|
FoundAll:
|
|
FoundEFILDR:
|
|
movw %bx, %cx # cx = Start Cluster for EFILDR <----------------------------------
|
|
movw %cs, %ax # Destination = 2000:0000
|
|
addw $0x2000, %ax
|
|
movw %ax, %es
|
|
xorw %di, %di
|
|
ReadFirstClusterOfEFILDR:
|
|
movw %cx, %ax # ax = StartCluster
|
|
subw $2, %ax # ax = StartCluster - 2
|
|
xorb %bh, %bh
|
|
movb SectorsPerCluster(%bp), %bl # bx = SectorsPerCluster
|
|
pushw %dx
|
|
mulw %bx
|
|
popw %dx # ax = (StartCluster - 2) * SectorsPerCluster
|
|
addw (%bp), %ax # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
|
|
xorb %bh, %bh
|
|
movb SectorsPerCluster(%bp), %bl # bx = Number of Sectors in a cluster
|
|
pushw %es
|
|
call ReadBlocks
|
|
popw %ax
|
|
JumpIntoFirstSectorOfEFILDR:
|
|
movw %ax, JumpSegment(%bp)
|
|
JumpFarInstruction:
|
|
.byte 0xea
|
|
JumpOffset:
|
|
.word 0x000
|
|
JumpSegment:
|
|
.word 0x2000
|
|
|
|
|
|
PrintString:
|
|
movw $0xb800, %ax
|
|
movw %ax, %es
|
|
movw $0x7c0, %ax
|
|
movw %ax, %ds
|
|
movw $7, %cx
|
|
movw $160, %di
|
|
rep
|
|
movsw
|
|
ret
|
|
# ****************************************************************************
|
|
# ReadBlocks - Reads a set of blocks from a block device
|
|
#
|
|
# AX = Start LBA
|
|
# BX = Number of Blocks to Read
|
|
# ES:DI = Buffer to store sectors read from disk
|
|
# ****************************************************************************
|
|
|
|
# cx = Blocks
|
|
# bx = NumberOfBlocks
|
|
# si = StartLBA
|
|
|
|
ReadBlocks:
|
|
pusha
|
|
addl LBAOffsetForBootSector(%bp), %eax # Add LBAOffsetForBootSector to Start LBA
|
|
addl HiddenSectors(%bp), %eax # Add HiddenSectors to Start LBA
|
|
movl %eax, %esi # esi = Start LBA
|
|
movw %bx, %cx # cx = Number of blocks to read
|
|
ReadCylinderLoop:
|
|
movw $0x7bfc, %bp # bp = 0x7bfc
|
|
movl %esi, %eax # eax = Start LBA
|
|
xorl %edx, %edx # edx = 0
|
|
movzwl (%bp), %ebx # bx = MaxSector
|
|
divl %ebx # ax = StartLBA / MaxSector
|
|
incw %dx # dx = (StartLBA % MaxSector) + 1
|
|
subw %dx, %bx # bx = MaxSector - Sector
|
|
incw %bx # bx = MaxSector - Sector + 1
|
|
cmpw %bx, %cx # Compare (Blocks) to (MaxSector - Sector + 1)
|
|
jg LimitTransfer
|
|
movw %cx, %bx # bx = Blocks
|
|
LimitTransfer:
|
|
pushw %cx
|
|
movb %dl, %cl # cl = (StartLBA % MaxSector) + 1 = Sector
|
|
xorw %dx, %dx # dx = 0
|
|
divw 2(%bp) # ax = ax / (MaxHead + 1) = Cylinder
|
|
# dx = ax % (MaxHead + 1) = Head
|
|
|
|
pushw %bx # Save number of blocks to transfer
|
|
movb %dl, %dh # dh = Head
|
|
movw $0x7c00, %bp # bp = 0x7c00
|
|
movb PhysicalDrive(%bp), %dl # dl = Drive Number
|
|
movb %al, %ch # ch = Cylinder
|
|
movb %bl, %al # al = Blocks
|
|
movb $2, %ah # ah = Function 2
|
|
movw %di, %bx # es:bx = Buffer address
|
|
int $0x13
|
|
jc DiskError
|
|
popw %bx
|
|
popw %cx
|
|
movzwl %bx, %ebx
|
|
addl %ebx, %esi # StartLBA = StartLBA + NumberOfBlocks
|
|
subw %bx, %cx # Blocks = Blocks - NumberOfBlocks
|
|
movw %es, %ax
|
|
shlw $(BLOCK_SHIFT-4), %bx
|
|
addw %bx, %ax
|
|
movw %ax, %es # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
|
|
cmpw $0, %cx
|
|
jne ReadCylinderLoop
|
|
popa
|
|
ret
|
|
|
|
# ****************************************************************************
|
|
# ERROR Condition:
|
|
# ****************************************************************************
|
|
NotFoundAll:
|
|
## if we found EFILDR, continue
|
|
testw %bx, %bx
|
|
jne FoundEFILDR
|
|
BadBootSector:
|
|
DiskError:
|
|
leaw %cs:ErrorString, %si
|
|
call PrintString
|
|
Halt:
|
|
jmp Halt
|
|
|
|
StartString:
|
|
.byte 'B', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c, '!', 0x0c
|
|
ErrorString:
|
|
.byte 'B', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c
|
|
|
|
# ****************************************************************************
|
|
# LBA Offset for BootSector, need patched by tool for HD boot.
|
|
# ****************************************************************************
|
|
|
|
# .org 0x01fa # Comment it for pass build. Should optimise code size.
|
|
LBAOffsetForBootSector:
|
|
.long 0x0
|
|
|
|
# ****************************************************************************
|
|
# Sector Signature
|
|
# ****************************************************************************
|
|
|
|
# .org 0x01fe # Comment it for pass build.
|
|
SectorSignature:
|
|
.word 0xaa55 # Boot Sector Signature
|
|
|
|
|
|
|