160 lines
2.1 KiB
NASM
160 lines
2.1 KiB
NASM
cpu 8086
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org 0x0000
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db 0x55, 0xAA
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db 0x00
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jmp init
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nop
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times (0x18 - ($-$$)) db 0
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dw 0
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dw pnp
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pnp: db "$PnP"
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db 1 ; version 1
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db 2 ; 2 * 16 length
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dw 0 ; offset of next header
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db 0
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db 0 ; checksum (filled by fix-rom)
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dd 0 ; device identifier
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dw 0 ; manufacturer string
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dw name ; product name string
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db 0,0,0 ; device type string
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db 0x20 ; device indicator, bit for "read cacheable" set
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dw 0 ; boot connection vector
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dw 0 ; boot disconnect vector
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dw 0 ; bootstrap entry point
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dw 0 ; reserved
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dw 0
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name: db "dprintf"
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init: push ds
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push ax
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xor ax, ax
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mov ds, ax
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mov word [1*4], int3entry
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mov word [1*4+2], cs
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mov word [3*4], int3entry
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mov word [3*4+2], cs
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pop ax
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pop ds
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retf
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crlf: xor bx, bx
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mov ax, 0x0e0a
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int 0x10
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mov al, 0x0d
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int 0x10
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ret
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printr: mov al, cl
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int 0x10
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mov al, ch
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int 0x10
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mov al, '='
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int 0x10
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call printd
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mov al, ' '
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int 0x10
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ret
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printd: mov cl, 4
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; this double-call is essentially a 4 times repeating loop
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call .c1
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.c1: call .c2
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.c2: ; grab highest nibble from dx
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mov al, dh
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; remove highest nibble from dx
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shl dx, cl
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; shift away second-highest nibble that we accidentally copied
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shr al, cl
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; map 0-9 to ascii codes for '0' to '9'
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add al, 0x30
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; if result is larger than '9', ...
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cmp al, 0x3a
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jl .noadj
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; ... add 7 so we continue at 'A'
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add al, 7
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.noadj: int 0x10
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ret
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int3entry:
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push bx
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push dx
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push cx
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push ax
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push bp
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mov bp, sp
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call crlf
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xor bx, bx
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mov ah, 0x0e
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mov cx, 'AX'
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mov dx, [bp+2]
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call printr
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mov cx, 'CX'
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mov dx, [bp+4]
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call printr
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mov cx, 'DX'
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mov dx, [bp+6]
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call printr
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mov cx, 'BX'
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mov dx, [bp+8]
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call printr
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mov cx, 'BP'
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mov dx, [bp]
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call printr
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mov cx, 'SP'
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lea dx, [bp+16]
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call printr
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mov cx, 'SI'
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mov dx, si
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call printr
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mov cx, 'DI'
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mov dx, di
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call printr
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call crlf
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mov cx, 'ES'
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mov dx, es
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call printr
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mov cx, 'CS'
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mov dx, [bp+12]
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call printr
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mov cx, 'SS'
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mov dx, ss
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call printr
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mov cx, 'DS'
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mov dx, ds
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call printr
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mov cx, 'IP'
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mov dx, [bp+10]
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call printr
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call crlf
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pop bp
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pop ax
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pop cx
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pop dx
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pop bx
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iret
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align 512
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