109 lines
1.7 KiB
NASM
109 lines
1.7 KiB
NASM
org 0x7c00
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bits 16
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jmp skip_bpb
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nop
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; El Torito Boot Information Table
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; ↓ Set by mkisofs
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times 8-($-$$) db 0
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boot_info:
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bi_PVD dd 0
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bi_boot_LBA dd 0
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bi_boot_len dd 0
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bi_checksum dd 0
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bi_reserved times 40 db 0
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times 90-($-$$) 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 si, si
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mov ds, si
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mov es, si
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mov ss, si
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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.0
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cmp bx, 0xaa55
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jne err.1
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; --- Load the decompressor ---
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mov eax, dword [bi_boot_LBA]
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add eax, 1
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mov ecx, stage2.fullsize / 2048
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; DECOMPRESSOR_LOCATION = 0x70000 = 0x7000:0x0000
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push 0x7000
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pop es
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xor bx, bx
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call read_2k_sectors
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jc err.2
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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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.2:
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inc si
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.1:
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inc si
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.0:
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add si, '0' | (0x4f << 8)
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push 0xb800
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pop es
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mov word [es:0], si
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sti
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.h: hlt
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jmp .h
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%include 'read_2k_sectors.asm'
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%include '../gdt.asm'
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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 decompressor
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push 2
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and edx, 0xff
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push edx ; Boot drive
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push stage2.size
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push (stage2 - decompressor) + 0x70000
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call 0x70000
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; Align stage2 to 2K ON DISK
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times 2048-($-$$) db 0
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decompressor:
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%strcat DECOMPRESSOR_PATH BUILDDIR, '/decompressor-build/decompressor.bin'
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incbin DECOMPRESSOR_PATH
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align 16
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stage2:
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%strcat STAGE2_PATH BUILDDIR, '/common-bios/stage2.bin.gz'
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incbin STAGE2_PATH
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.size: equ $ - stage2
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times ((($-$$)+2047) & ~2047)-($-$$) db 0
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.fullsize: equ $ - decompressor
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