132f9b796d3bb05f608d87d49e691249e5f04d13ejji#------------------------------------------------------------------------------ 232f9b796d3bb05f608d87d49e691249e5f04d13ejji#* 3e7c4ef5ed4a1b14c7514367a5a95e1d9c9e1f090rsun#* Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR> 4b1f700a8593435e2bdc8f9b3dc21bced4774c80fhhtian#* This program and the accompanying materials 532f9b796d3bb05f608d87d49e691249e5f04d13ejji#* are licensed and made available under the terms and conditions of the BSD License 632f9b796d3bb05f608d87d49e691249e5f04d13ejji#* which accompanies this distribution. The full text of the license may be found at 732f9b796d3bb05f608d87d49e691249e5f04d13ejji#* http://opensource.org/licenses/bsd-license.php 832f9b796d3bb05f608d87d49e691249e5f04d13ejji#* 932f9b796d3bb05f608d87d49e691249e5f04d13ejji#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 1032f9b796d3bb05f608d87d49e691249e5f04d13ejji#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 1132f9b796d3bb05f608d87d49e691249e5f04d13ejji#* 1232f9b796d3bb05f608d87d49e691249e5f04d13ejji#* bs32.asm 1332f9b796d3bb05f608d87d49e691249e5f04d13ejji#* 1432f9b796d3bb05f608d87d49e691249e5f04d13ejji#* Abstract: 1532f9b796d3bb05f608d87d49e691249e5f04d13ejji#* 1632f9b796d3bb05f608d87d49e691249e5f04d13ejji#------------------------------------------------------------------------------ 1732f9b796d3bb05f608d87d49e691249e5f04d13ejji 1832f9b796d3bb05f608d87d49e691249e5f04d13ejji #.MODEL small 1920193e01ca7f2e20c8be6b412c8cf0a5132d1c1cklu .stack: 2020193e01ca7f2e20c8be6b412c8cf0a5132d1c1cklu .486p: 2120193e01ca7f2e20c8be6b412c8cf0a5132d1c1cklu .code16 2232f9b796d3bb05f608d87d49e691249e5f04d13ejji 2332f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ FAT_DIRECTORY_ENTRY_SIZE, 0x0020 2432f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ FAT_DIRECTORY_ENTRY_SHIFT, 5 2532f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ BLOCK_SIZE, 0x0200 2632f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ BLOCK_MASK, 0x01ff 2732f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ BLOCK_SHIFT, 9 2832f9b796d3bb05f608d87d49e691249e5f04d13ejji # "EFILDR_____" 2932f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ LOADER_FILENAME_PART1, 0x4c494645 # "EFIL" 3032f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ LOADER_FILENAME_PART2, 0x30325244 # "DR20" 3132f9b796d3bb05f608d87d49e691249e5f04d13ejji.equ LOADER_FILENAME_PART3, 0x20202030 # "0___" 3232f9b796d3bb05f608d87d49e691249e5f04d13ejji 33d5172f911d21d03a3a4f50cb6ebe89854d191e4dxli .org 0x0 34c27b9ffe86a8c1d8476154f725682ad2afa8e7d5Tian, Hot.global _start 35fd549a4db9c562587652c23884bab5a4f3631d10gikidy_start: 3632f9b796d3bb05f608d87d49e691249e5f04d13ejjiIa32Jump: 3732f9b796d3bb05f608d87d49e691249e5f04d13ejji jmp BootSectorEntryPoint # JMP inst - 3 bytes 3832f9b796d3bb05f608d87d49e691249e5f04d13ejji nop 3932f9b796d3bb05f608d87d49e691249e5f04d13ejji 409ffd16fb498e2f45c68f88210d8b6daf88deacb5jjiOemId: .ascii "INTEL " # OemId - 8 bytes 4132f9b796d3bb05f608d87d49e691249e5f04d13ejji# BPB data below will be fixed by tool 4232f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectorSize: .word 0 # Sector Size - 16 bits 4332f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectorsPerCluster: .byte 0 # Sector Per Cluster - 8 bits 4432f9b796d3bb05f608d87d49e691249e5f04d13ejjiReservedSectors: .word 0 # Reserved Sectors - 16 bits 4532f9b796d3bb05f608d87d49e691249e5f04d13ejjiNoFats: .byte 0 # Number of FATs - 8 bits 4632f9b796d3bb05f608d87d49e691249e5f04d13ejjiRootEntries: .word 0 # Root Entries - 16 bits 4732f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectors: .word 0 # Number of Sectors - 16 bits 4832f9b796d3bb05f608d87d49e691249e5f04d13ejjiMedia: .byte 0 # Media - 8 bits - ignored 4932f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectorsPerFat: .word 0 # Sectors Per FAT - 16 bits 5032f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectorsPerTrack: .word 0 # Sectors Per Track - 16 bits - ignored 5132f9b796d3bb05f608d87d49e691249e5f04d13ejjiHeads: .word 0 # Heads - 16 bits - ignored 5232f9b796d3bb05f608d87d49e691249e5f04d13ejjiHiddenSectors: .long 0 # Hidden Sectors - 32 bits - ignored 5332f9b796d3bb05f608d87d49e691249e5f04d13ejjiLargeSectors: .long 0 # Large Sectors - 32 bits 5432f9b796d3bb05f608d87d49e691249e5f04d13ejji 5532f9b796d3bb05f608d87d49e691249e5f04d13ejji#****************************************************************************** 5632f9b796d3bb05f608d87d49e691249e5f04d13ejji# 5732f9b796d3bb05f608d87d49e691249e5f04d13ejji#The structure for FAT32 starting at offset 36 of the boot sector. (At this point, 5832f9b796d3bb05f608d87d49e691249e5f04d13ejji#the BPB/boot sector for FAT12 and FAT16 differs from the BPB/boot sector for FAT32.) 5932f9b796d3bb05f608d87d49e691249e5f04d13ejji# 6032f9b796d3bb05f608d87d49e691249e5f04d13ejji#****************************************************************************** 6132f9b796d3bb05f608d87d49e691249e5f04d13ejji 6232f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectorsPerFat32: .long 0 # Sectors Per FAT for FAT32 - 4 bytes 6332f9b796d3bb05f608d87d49e691249e5f04d13ejjiExtFlags: .word 0 # Mirror Flag - 2 bytes 6432f9b796d3bb05f608d87d49e691249e5f04d13ejjiFSVersion: .word 0 # File System Version - 2 bytes 6532f9b796d3bb05f608d87d49e691249e5f04d13ejjiRootCluster: .long 0 # 1st Cluster Number of Root Dir - 4 bytes 6632f9b796d3bb05f608d87d49e691249e5f04d13ejjiFSInfo: .word 0 # Sector Number of FSINFO - 2 bytes 6732f9b796d3bb05f608d87d49e691249e5f04d13ejjiBkBootSector: .word 0 # Sector Number of Bk BootSector - 2 bytes 6832f9b796d3bb05f608d87d49e691249e5f04d13ejjiReserved: .fill 12, 1, 0 # Reserved Field - 12 bytes 6932f9b796d3bb05f608d87d49e691249e5f04d13ejjiPhysicalDrive: .byte 0 # Physical Drive Number - 1 byte 7032f9b796d3bb05f608d87d49e691249e5f04d13ejjiReserved1: .byte 0 # Reserved Field - 1 byte 7132f9b796d3bb05f608d87d49e691249e5f04d13ejjiSignature: .byte 0 # Extended Boot Signature - 1 byte 7232f9b796d3bb05f608d87d49e691249e5f04d13ejjiVolId: .ascii " " # Volume Serial Number - 4 bytes 7332f9b796d3bb05f608d87d49e691249e5f04d13ejjiFatLabel: .ascii " " # Volume Label - 11 bytes 7432f9b796d3bb05f608d87d49e691249e5f04d13ejjiFileSystemType: .ascii "FAT32 " # File System Type - 8 bytes 7532f9b796d3bb05f608d87d49e691249e5f04d13ejjiBootSectorEntryPoint: 7632f9b796d3bb05f608d87d49e691249e5f04d13ejji #ASSUME ds:@code 7732f9b796d3bb05f608d87d49e691249e5f04d13ejji #ASSUME ss:@code 7832f9b796d3bb05f608d87d49e691249e5f04d13ejji 7932f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 8032f9b796d3bb05f608d87d49e691249e5f04d13ejji# Start Print 8132f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 8220193e01ca7f2e20c8be6b412c8cf0a5132d1c1cklu movw $StartString, %si 8332f9b796d3bb05f608d87d49e691249e5f04d13ejji call PrintString 8432f9b796d3bb05f608d87d49e691249e5f04d13ejji 8532f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 8632f9b796d3bb05f608d87d49e691249e5f04d13ejji# Print over 8732f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 8832f9b796d3bb05f608d87d49e691249e5f04d13ejji 8932f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %cs, %ax # ax = 0 9032f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, %ss # ss = 0 9132f9b796d3bb05f608d87d49e691249e5f04d13ejji addw $0x1000, %ax 9232f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, %ds 9332f9b796d3bb05f608d87d49e691249e5f04d13ejji 9432f9b796d3bb05f608d87d49e691249e5f04d13ejji movw $0x7c00, %sp # sp = 0x7c00 9532f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %sp, %bp # bp = 0x7c00 9632f9b796d3bb05f608d87d49e691249e5f04d13ejji 9732f9b796d3bb05f608d87d49e691249e5f04d13ejji movb $8, %ah # ah = 8 - Get Drive Parameters Function 9832f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %dl, PhysicalDrive(%bp) # BBS defines that BIOS would pass the booting driver number to the loader through DL 9932f9b796d3bb05f608d87d49e691249e5f04d13ejji int $0x13 # Get Drive Parameters 10032f9b796d3bb05f608d87d49e691249e5f04d13ejji xorw %ax, %ax # ax = 0 10132f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %dh, %al # al = dh 10232f9b796d3bb05f608d87d49e691249e5f04d13ejji incb %al # MaxHead = al + 1 10332f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %ax # 0000:7bfe = MaxHead 10432f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %cl, %al # al = cl 10532f9b796d3bb05f608d87d49e691249e5f04d13ejji andb $0x3f, %al # MaxSector = al & 0x3f 10632f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %ax # 0000:7bfc = MaxSector 10732f9b796d3bb05f608d87d49e691249e5f04d13ejji 10832f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpw $0xaa55, SectorSignature(%bp) # Verify Boot Sector Signature 10932f9b796d3bb05f608d87d49e691249e5f04d13ejji jne BadBootSector 11032f9b796d3bb05f608d87d49e691249e5f04d13ejji movw RootEntries(%bp), %cx # cx = RootEntries 11132f9b796d3bb05f608d87d49e691249e5f04d13ejji shlw $FAT_DIRECTORY_ENTRY_SHIFT, %cx # cx = cx * 32 = cx * sizeof(FAT_DIRECTORY_ENTRY) = Size of Root Directory in bytes 11232f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %cx, %bx # bx = size of the Root Directory in bytes 11332f9b796d3bb05f608d87d49e691249e5f04d13ejji andw $BLOCK_MASK, %bx # See if it is an even number of sectors long 11432f9b796d3bb05f608d87d49e691249e5f04d13ejji jne BadBootSector # If is isn't, then the boot sector is bad. 11532f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %cx, %bx # bx = size of the Root Directory in bytes 11632f9b796d3bb05f608d87d49e691249e5f04d13ejji shrw $BLOCK_SHIFT, %bx # bx = size of Root Directory in sectors 11732f9b796d3bb05f608d87d49e691249e5f04d13ejji movb NoFats(%bp), %al # al = NoFats 11832f9b796d3bb05f608d87d49e691249e5f04d13ejji xorb %ah, %ah # ah = 0 ==> ax = NoFats 11932f9b796d3bb05f608d87d49e691249e5f04d13ejji mulw SectorsPerFat32(%bp) # ax = NoFats * SectorsPerFat 12032f9b796d3bb05f608d87d49e691249e5f04d13ejji addw ReservedSectors(%bp), %ax # ax = NoFats * SectorsPerFat + ReservedSectors = RootLBA 12132f9b796d3bb05f608d87d49e691249e5f04d13ejji addw %bx, %ax # ax = NoFats * SectorsPerFat + ReservedSectors + RootDirSectors = FirstClusterLBA 12232f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, (%bp) # Save FirstClusterLBA for later use 12332f9b796d3bb05f608d87d49e691249e5f04d13ejji 12432f9b796d3bb05f608d87d49e691249e5f04d13ejji movw RootCluster(%bp), %ax # ax = StartCluster of Root Directory 12532f9b796d3bb05f608d87d49e691249e5f04d13ejji subw $2, %ax # ax = StartCluster - 2 12632f9b796d3bb05f608d87d49e691249e5f04d13ejji xorb %bh, %bh 12732f9b796d3bb05f608d87d49e691249e5f04d13ejji movb SectorsPerCluster(%bp), %bl # bx = SectorsPerCluster 12832f9b796d3bb05f608d87d49e691249e5f04d13ejji mulw %bx # ax = (StartCluster - 2) * SectorsPerCluster 12932f9b796d3bb05f608d87d49e691249e5f04d13ejji addw (%bp), %ax # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster 13032f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %ds 13132f9b796d3bb05f608d87d49e691249e5f04d13ejji popw %es 13232f9b796d3bb05f608d87d49e691249e5f04d13ejji xorw %di, %di # Store directory in es:di = 1000:0000 13332f9b796d3bb05f608d87d49e691249e5f04d13ejji call ReadBlocks # Read StartCluster of Root Directory 13432f9b796d3bb05f608d87d49e691249e5f04d13ejji 13532f9b796d3bb05f608d87d49e691249e5f04d13ejji # dx - variable storage (initial value is 0) 13632f9b796d3bb05f608d87d49e691249e5f04d13ejji # bx - loader (initial value is 0) 13732f9b796d3bb05f608d87d49e691249e5f04d13ejji xorw %dx, %dx 13832f9b796d3bb05f608d87d49e691249e5f04d13ejji xorw %bx, %bx 13932f9b796d3bb05f608d87d49e691249e5f04d13ejji 14032f9b796d3bb05f608d87d49e691249e5f04d13ejjiFindEFILDR: 14132f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpl $LOADER_FILENAME_PART1, (%di) 14232f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindVARSTORE 14332f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpl $LOADER_FILENAME_PART2, 4(%di) 14432f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindVARSTORE 14532f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpl $LOADER_FILENAME_PART3, 7(%di) 14632f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindVARSTORE 14732f9b796d3bb05f608d87d49e691249e5f04d13ejji movw 26(%di), %bx # bx = Start Cluster for EFILDR <---------------------------------- 14832f9b796d3bb05f608d87d49e691249e5f04d13ejji testw %dx, %dx 14932f9b796d3bb05f608d87d49e691249e5f04d13ejji je FindNext # Efivar.bin is not loaded 15032f9b796d3bb05f608d87d49e691249e5f04d13ejji jmp FoundAll 15132f9b796d3bb05f608d87d49e691249e5f04d13ejji 15232f9b796d3bb05f608d87d49e691249e5f04d13ejjiFindVARSTORE: 153fd549a4db9c562587652c23884bab5a4f3631d10gikidy ## if the file is not loader file, see if it's "EFIVAR BIN" 15432f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpl $0x56494645, (%di) # Compare to "EFIV" 15532f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindNext 15632f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpl $0x20205241, 4(%di) # Compare to "AR " 15732f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindNext 15832f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpl $0x4e494220, 7(%di) # Compare to " BIN" 15932f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindNext 16032f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %di, %dx # dx = Offset of Start Cluster for Efivar.bin <--------------------- 16132f9b796d3bb05f608d87d49e691249e5f04d13ejji addw $26, %dx 16232f9b796d3bb05f608d87d49e691249e5f04d13ejji testw %bx, %bx 16332f9b796d3bb05f608d87d49e691249e5f04d13ejji je FindNext # Efildr is not loaded 16432f9b796d3bb05f608d87d49e691249e5f04d13ejji jmp FoundAll 16532f9b796d3bb05f608d87d49e691249e5f04d13ejji 16632f9b796d3bb05f608d87d49e691249e5f04d13ejjiFindNext: 16732f9b796d3bb05f608d87d49e691249e5f04d13ejji # go to next find 16832f9b796d3bb05f608d87d49e691249e5f04d13ejji addw $FAT_DIRECTORY_ENTRY_SIZE, %di # Increment di 16932f9b796d3bb05f608d87d49e691249e5f04d13ejji subw $FAT_DIRECTORY_ENTRY_SIZE, %cx # Decrement cx 17032f9b796d3bb05f608d87d49e691249e5f04d13ejji # TODO: jump to FindVarStore if ... 17132f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FindEFILDR 17232f9b796d3bb05f608d87d49e691249e5f04d13ejji jmp NotFoundAll 17332f9b796d3bb05f608d87d49e691249e5f04d13ejji 17432f9b796d3bb05f608d87d49e691249e5f04d13ejjiFoundAll: 17532f9b796d3bb05f608d87d49e691249e5f04d13ejjiFoundEFILDR: 17632f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %bx, %cx # cx = Start Cluster for EFILDR <---------------------------------- 17732f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %cs, %ax # Destination = 2000:0000 17832f9b796d3bb05f608d87d49e691249e5f04d13ejji addw $0x2000, %ax 17932f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, %es 18032f9b796d3bb05f608d87d49e691249e5f04d13ejji xorw %di, %di 18132f9b796d3bb05f608d87d49e691249e5f04d13ejjiReadFirstClusterOfEFILDR: 18232f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %cx, %ax # ax = StartCluster 18332f9b796d3bb05f608d87d49e691249e5f04d13ejji subw $2, %ax # ax = StartCluster - 2 18432f9b796d3bb05f608d87d49e691249e5f04d13ejji xorb %bh, %bh 18532f9b796d3bb05f608d87d49e691249e5f04d13ejji movb SectorsPerCluster(%bp), %bl # bx = SectorsPerCluster 18632f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %dx 18732f9b796d3bb05f608d87d49e691249e5f04d13ejji mulw %bx 18832f9b796d3bb05f608d87d49e691249e5f04d13ejji popw %dx # ax = (StartCluster - 2) * SectorsPerCluster 18932f9b796d3bb05f608d87d49e691249e5f04d13ejji addw (%bp), %ax # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster 19032f9b796d3bb05f608d87d49e691249e5f04d13ejji xorb %bh, %bh 19132f9b796d3bb05f608d87d49e691249e5f04d13ejji movb SectorsPerCluster(%bp), %bl # bx = Number of Sectors in a cluster 19232f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %es 19332f9b796d3bb05f608d87d49e691249e5f04d13ejji call ReadBlocks 19432f9b796d3bb05f608d87d49e691249e5f04d13ejji popw %ax 19532f9b796d3bb05f608d87d49e691249e5f04d13ejjiJumpIntoFirstSectorOfEFILDR: 19632f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, JumpSegment(%bp) 19732f9b796d3bb05f608d87d49e691249e5f04d13ejjiJumpFarInstruction: 19832f9b796d3bb05f608d87d49e691249e5f04d13ejji .byte 0xea 19932f9b796d3bb05f608d87d49e691249e5f04d13ejjiJumpOffset: 20032f9b796d3bb05f608d87d49e691249e5f04d13ejji .word 0x000 20132f9b796d3bb05f608d87d49e691249e5f04d13ejjiJumpSegment: 20232f9b796d3bb05f608d87d49e691249e5f04d13ejji .word 0x2000 20332f9b796d3bb05f608d87d49e691249e5f04d13ejji 20432f9b796d3bb05f608d87d49e691249e5f04d13ejji 20532f9b796d3bb05f608d87d49e691249e5f04d13ejjiPrintString: 20632f9b796d3bb05f608d87d49e691249e5f04d13ejji movw $0xb800, %ax 20732f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, %es 20832f9b796d3bb05f608d87d49e691249e5f04d13ejji movw $0x7c0, %ax 20932f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, %ds 210e7c4ef5ed4a1b14c7514367a5a95e1d9c9e1f090rsun movw $6, %cx 21132f9b796d3bb05f608d87d49e691249e5f04d13ejji movw $160, %di 21232f9b796d3bb05f608d87d49e691249e5f04d13ejji rep 21332f9b796d3bb05f608d87d49e691249e5f04d13ejji movsw 21432f9b796d3bb05f608d87d49e691249e5f04d13ejji ret 21532f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 21632f9b796d3bb05f608d87d49e691249e5f04d13ejji# ReadBlocks - Reads a set of blocks from a block device 21732f9b796d3bb05f608d87d49e691249e5f04d13ejji# 21832f9b796d3bb05f608d87d49e691249e5f04d13ejji# AX = Start LBA 21932f9b796d3bb05f608d87d49e691249e5f04d13ejji# BX = Number of Blocks to Read 22032f9b796d3bb05f608d87d49e691249e5f04d13ejji# ES:DI = Buffer to store sectors read from disk 22132f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 22232f9b796d3bb05f608d87d49e691249e5f04d13ejji 22332f9b796d3bb05f608d87d49e691249e5f04d13ejji# cx = Blocks 22432f9b796d3bb05f608d87d49e691249e5f04d13ejji# bx = NumberOfBlocks 22532f9b796d3bb05f608d87d49e691249e5f04d13ejji# si = StartLBA 22632f9b796d3bb05f608d87d49e691249e5f04d13ejji 22732f9b796d3bb05f608d87d49e691249e5f04d13ejjiReadBlocks: 22832f9b796d3bb05f608d87d49e691249e5f04d13ejji pusha 22932f9b796d3bb05f608d87d49e691249e5f04d13ejji addl LBAOffsetForBootSector(%bp), %eax # Add LBAOffsetForBootSector to Start LBA 23032f9b796d3bb05f608d87d49e691249e5f04d13ejji addl HiddenSectors(%bp), %eax # Add HiddenSectors to Start LBA 23132f9b796d3bb05f608d87d49e691249e5f04d13ejji movl %eax, %esi # esi = Start LBA 23232f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %bx, %cx # cx = Number of blocks to read 23332f9b796d3bb05f608d87d49e691249e5f04d13ejjiReadCylinderLoop: 23432f9b796d3bb05f608d87d49e691249e5f04d13ejji movw $0x7bfc, %bp # bp = 0x7bfc 23532f9b796d3bb05f608d87d49e691249e5f04d13ejji movl %esi, %eax # eax = Start LBA 23632f9b796d3bb05f608d87d49e691249e5f04d13ejji xorl %edx, %edx # edx = 0 23732f9b796d3bb05f608d87d49e691249e5f04d13ejji movzwl (%bp), %ebx # bx = MaxSector 23832f9b796d3bb05f608d87d49e691249e5f04d13ejji divl %ebx # ax = StartLBA / MaxSector 23932f9b796d3bb05f608d87d49e691249e5f04d13ejji incw %dx # dx = (StartLBA % MaxSector) + 1 24032f9b796d3bb05f608d87d49e691249e5f04d13ejji subw %dx, %bx # bx = MaxSector - Sector 24132f9b796d3bb05f608d87d49e691249e5f04d13ejji incw %bx # bx = MaxSector - Sector + 1 24232f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpw %bx, %cx # Compare (Blocks) to (MaxSector - Sector + 1) 24332f9b796d3bb05f608d87d49e691249e5f04d13ejji jg LimitTransfer 24432f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %cx, %bx # bx = Blocks 24532f9b796d3bb05f608d87d49e691249e5f04d13ejjiLimitTransfer: 24632f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %cx 24732f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %dl, %cl # cl = (StartLBA % MaxSector) + 1 = Sector 24832f9b796d3bb05f608d87d49e691249e5f04d13ejji xorw %dx, %dx # dx = 0 24932f9b796d3bb05f608d87d49e691249e5f04d13ejji divw 2(%bp) # ax = ax / (MaxHead + 1) = Cylinder 25032f9b796d3bb05f608d87d49e691249e5f04d13ejji # dx = ax % (MaxHead + 1) = Head 25132f9b796d3bb05f608d87d49e691249e5f04d13ejji 25232f9b796d3bb05f608d87d49e691249e5f04d13ejji pushw %bx # Save number of blocks to transfer 25332f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %dl, %dh # dh = Head 25432f9b796d3bb05f608d87d49e691249e5f04d13ejji movw $0x7c00, %bp # bp = 0x7c00 25532f9b796d3bb05f608d87d49e691249e5f04d13ejji movb PhysicalDrive(%bp), %dl # dl = Drive Number 25632f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %al, %ch # ch = Cylinder 25732f9b796d3bb05f608d87d49e691249e5f04d13ejji movb %bl, %al # al = Blocks 25832f9b796d3bb05f608d87d49e691249e5f04d13ejji movb $2, %ah # ah = Function 2 25932f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %di, %bx # es:bx = Buffer address 26032f9b796d3bb05f608d87d49e691249e5f04d13ejji int $0x13 26132f9b796d3bb05f608d87d49e691249e5f04d13ejji jc DiskError 26232f9b796d3bb05f608d87d49e691249e5f04d13ejji popw %bx 26332f9b796d3bb05f608d87d49e691249e5f04d13ejji popw %cx 26432f9b796d3bb05f608d87d49e691249e5f04d13ejji movzwl %bx, %ebx 26532f9b796d3bb05f608d87d49e691249e5f04d13ejji addl %ebx, %esi # StartLBA = StartLBA + NumberOfBlocks 26632f9b796d3bb05f608d87d49e691249e5f04d13ejji subw %bx, %cx # Blocks = Blocks - NumberOfBlocks 26732f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %es, %ax 26832f9b796d3bb05f608d87d49e691249e5f04d13ejji shlw $(BLOCK_SHIFT-4), %bx 26932f9b796d3bb05f608d87d49e691249e5f04d13ejji addw %bx, %ax 27032f9b796d3bb05f608d87d49e691249e5f04d13ejji movw %ax, %es # es:di = es:di + NumberOfBlocks*BLOCK_SIZE 27132f9b796d3bb05f608d87d49e691249e5f04d13ejji cmpw $0, %cx 27232f9b796d3bb05f608d87d49e691249e5f04d13ejji jne ReadCylinderLoop 27332f9b796d3bb05f608d87d49e691249e5f04d13ejji popa 27432f9b796d3bb05f608d87d49e691249e5f04d13ejji ret 27532f9b796d3bb05f608d87d49e691249e5f04d13ejji 27632f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 27732f9b796d3bb05f608d87d49e691249e5f04d13ejji# ERROR Condition: 27832f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 27932f9b796d3bb05f608d87d49e691249e5f04d13ejjiNotFoundAll: 280fd549a4db9c562587652c23884bab5a4f3631d10gikidy ## if we found EFILDR, continue 28132f9b796d3bb05f608d87d49e691249e5f04d13ejji testw %bx, %bx 28232f9b796d3bb05f608d87d49e691249e5f04d13ejji jne FoundEFILDR 28332f9b796d3bb05f608d87d49e691249e5f04d13ejjiBadBootSector: 28432f9b796d3bb05f608d87d49e691249e5f04d13ejjiDiskError: 28520193e01ca7f2e20c8be6b412c8cf0a5132d1c1cklu movw $ErrorString, %si 28632f9b796d3bb05f608d87d49e691249e5f04d13ejji call PrintString 28732f9b796d3bb05f608d87d49e691249e5f04d13ejjiHalt: 28832f9b796d3bb05f608d87d49e691249e5f04d13ejji jmp Halt 28932f9b796d3bb05f608d87d49e691249e5f04d13ejji 29032f9b796d3bb05f608d87d49e691249e5f04d13ejjiStartString: 291e7c4ef5ed4a1b14c7514367a5a95e1d9c9e1f090rsun .byte 'B', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c 29232f9b796d3bb05f608d87d49e691249e5f04d13ejjiErrorString: 293e7c4ef5ed4a1b14c7514367a5a95e1d9c9e1f090rsun .byte 'B', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c 29432f9b796d3bb05f608d87d49e691249e5f04d13ejji 29532f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 29632f9b796d3bb05f608d87d49e691249e5f04d13ejji# LBA Offset for BootSector, need patched by tool for HD boot. 29732f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 29832f9b796d3bb05f608d87d49e691249e5f04d13ejji 299e7c4ef5ed4a1b14c7514367a5a95e1d9c9e1f090rsun .org 0x01fa 30032f9b796d3bb05f608d87d49e691249e5f04d13ejjiLBAOffsetForBootSector: 30132f9b796d3bb05f608d87d49e691249e5f04d13ejji .long 0x0 30232f9b796d3bb05f608d87d49e691249e5f04d13ejji 30332f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 30432f9b796d3bb05f608d87d49e691249e5f04d13ejji# Sector Signature 30532f9b796d3bb05f608d87d49e691249e5f04d13ejji# **************************************************************************** 30632f9b796d3bb05f608d87d49e691249e5f04d13ejji 307e7c4ef5ed4a1b14c7514367a5a95e1d9c9e1f090rsun .org 0x01fe 30832f9b796d3bb05f608d87d49e691249e5f04d13ejjiSectorSignature: 30932f9b796d3bb05f608d87d49e691249e5f04d13ejji .word 0xaa55 # Boot Sector Signature 31032f9b796d3bb05f608d87d49e691249e5f04d13ejji 31132f9b796d3bb05f608d87d49e691249e5f04d13ejji 31232f9b796d3bb05f608d87d49e691249e5f04d13ejji 313