2021-02-21 05:45:24 +03:00
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BITS 16
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ORG 0x7C00
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; Please read bootsect/bootsect.asm before this file
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%define ISO9660_BUFFER 0x8000
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%define ROOT_DIRECTORY 156
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%define ROOT_DIRECTORY_BUFFER (ISO9660_BUFFER + ROOT_DIRECTORY)
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%define DIRECTORY_RECORD_LENGTH 0
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%define DIRECTORY_RECORD_LBA 2
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%define DIRECTORY_RECORD_SIZE 10
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%define DIRECTORY_RECORD_FILENAME_LENGTH 32
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%define DIRECTORY_RECORD_FILENAME 33
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%define BOOT_FROM_CD 2
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jmp skip_bpb
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nop
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times 87 db 0
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skip_bpb:
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cli
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cld
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jmp 0x0000:.initialise_cs
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.initialise_cs:
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xor ax, ax
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mov ds, ax
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mov es, ax
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mov ss, ax
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mov sp, 0x7C00
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sti
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; int 13h?
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mov ah, 0x41
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mov bx, 0x55AA
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int 0x13
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jc err
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cmp bx, 0xAA55
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jne err
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mov esp, 0x7C00
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; --- Load the stage 2 ---
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; Find and load the PVD
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call findPVD
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jc err
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; Load the root directory
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mov eax, dword [ROOT_DIRECTORY_BUFFER + DIRECTORY_RECORD_LBA]
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mov ecx, dword [ROOT_DIRECTORY_BUFFER + DIRECTORY_RECORD_SIZE]
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mov esi, ecx ; Size, for read_file
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add ecx, 2047
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shr ecx, 11
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call read_2k_sectors
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jc err
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; Find and load '/BOOT'
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mov ebx, TXT_BOOT
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mov cl, TXT_BOOT_SZ
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call read_file
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jc err
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; Find and load '/BOOT/STAGES.BIN'
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mov ebx, TXT_STAGES
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mov cl, TXT_STAGES_SZ
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call read_file ; esi is set from the last call
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jc err
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; Enable GDT
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lgdt [gdt]
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cli
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mov eax, cr0
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or al, 1
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mov cr0, eax
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jmp 0x08:pmode
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err:
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hlt
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jmp err
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%include 'iso9660.asm'
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2021-02-22 22:43:51 +03:00
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%include '../hddboot/gdt.inc'
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2021-02-21 05:45:24 +03:00
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BITS 32
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pmode:
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mov eax, 0x10
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov ss, ax
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; Time to handle control over to the stage 2
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push BOOT_FROM_CD
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and edx, 0xFF
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push edx ; Boot drive
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call ISO9660_BUFFER
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hlt
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TXT_BOOT: db "BOOT"
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TXT_BOOT_SZ equ $ - TXT_BOOT
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TXT_STAGES: db "STAGES.BIN;1"
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TXT_STAGES_SZ equ $ - TXT_STAGES
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; Just making sure the entry point (ISO9660_BUFFER) is not reached
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times (0x8000 - 0x7C00) - ($ - $$) db 0
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