77 lines
1.0 KiB
NASM
77 lines
1.0 KiB
NASM
jmp init
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align 4
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db "rDos"
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align 8
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; hook interrupt 3
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db 3
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db 0
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dw int3entry
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dd 0
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; end of header
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db 0
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stacksize: equ 0x20
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init:
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mov ax, 0x0e33
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xor bx, bx
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int 0x10
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retf
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int3entry:
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; save DS and AX
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mov [cs:reg_ds], ds
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mov [cs:reg_ax], ax
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; use AX to load DS=CS
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mov ax, cs
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mov ds, ax
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; pop IP, CS and flags from stack
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pop ax
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mov [reg_ip], ax
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pop ax
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mov [reg_cs], ax
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pop ax
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mov [reg_fl], ax
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; save the other registers
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mov [reg_cx], cx
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mov [reg_dx], dx
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mov [reg_bx], bx
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mov [reg_sp], sp
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mov [reg_bp], bp
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mov [reg_si], si
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mov [reg_di], di
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; save other segment registers we can access
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mov [reg_ss], ss
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mov [reg_es], es
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; initialize other segments and setup stack
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mov es, ax
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mov ss, ax
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mov sp, (stack+stacksize)
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hlt: hlt
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jmp hlt
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reg_ax: dw 0
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reg_cx: dw 0
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reg_dx: dw 0
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reg_bx: dw 0
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reg_sp: dw 0
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reg_bp: dw 0
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reg_si: dw 0
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reg_di: dw 0
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reg_es: dw 0
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reg_cs: dw 0
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reg_ss: dw 0
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reg_ds: dw 0
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reg_ip: dw 0
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reg_fl: dw 0
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names: db "AXCXDXBXSPBPSIDI"
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db "DSESSSCSIPFL"
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stack: times stacksize dw 0
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align 16
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