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Diffstat (limited to 'DuetPkg/BootSector/bootsect.S')
| -rw-r--r-- | DuetPkg/BootSector/bootsect.S | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/DuetPkg/BootSector/bootsect.S b/DuetPkg/BootSector/bootsect.S new file mode 100644 index 0000000000..edf941bcb3 --- /dev/null +++ b/DuetPkg/BootSector/bootsect.S @@ -0,0 +1,289 @@ +#------------------------------------------------------------------------------
+#*
+#* 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
+
+
+
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