159 lines
1.6 KiB
NASM
159 lines
1.6 KiB
NASM
mov ax, 0x1000
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mov ds, ax
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mov si, welcome
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call print
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loop:
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mov si, prompt
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call print
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call read
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cmp byte [input], 0
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je loop
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mov si, input
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mov di, cmdhello
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call compare
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jc .hello
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mov si, input
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mov di, cmdecho
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call compare
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jc .echo
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mov si, unknown
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call print
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jmp loop
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.hello:
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mov si, hello
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call print
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jmp loop
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.echo:
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call read
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cmp byte [input], 0
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je loop
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mov si, input
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call print
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mov si, newline
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call print
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jmp loop
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print:
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lodsb
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cmp al, 0
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je .done
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mov ah, 0xe
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int 0x10
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jmp print
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.done:
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ret
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read:
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mov di, input
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mov cx, 0x80
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mov al, 0
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rep stosb
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mov di, input
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mov cl, 0
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.loop:
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mov ah, 0
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int 0x16
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cmp al, 0xd
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je .return
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cmp al, 0x8
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je .backspace
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cmp cl, 0x80
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je .loop
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cmp al, 0x20
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je .space
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cmp al, 0x9
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je .erase
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cmp al, 0
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je .loop
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.character:
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mov byte [di], 0
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mov ah, 0xe
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int 0x10
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stosb
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inc cl
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jmp .loop
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.erase:
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mov al, 0x20
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jmp .character
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.space:
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cmp byte [di], 0
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je .character
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mov al, byte [di]
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mov ah, 0xe
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int 0x10
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inc di
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inc cl
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jmp .loop
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.backspace:
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cmp cl, 0
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je .loop
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mov ah, 0xe
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int 0x10
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dec di
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dec cl
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jmp .loop
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.return:
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mov di, input.end
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.tspfind:
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dec di
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cmp byte [di], 0
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je .tspfind
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cmp byte [di], 0x20
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je .tsperase
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jmp .done
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.tsperase:
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mov al, 0
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stosb
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dec di
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jmp .tspfind
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.done:
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mov si, newline
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call print
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ret
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compare:
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mov al, [si]
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mov bl, [di]
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cmp al, bl
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jne .nequal
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cmp al, 0
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je .equal
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inc si
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inc di
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jmp compare
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.nequal:
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clc
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ret
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.equal:
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stc
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ret
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welcome:
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db 0xd, 0xa, "Welcome to EttinOS!", 0xd, 0xa, 0xd, 0xa, 0
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prompt:
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db "> ", 0
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newline:
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db 0xd, 0xa, 0
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input:
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times 0x80 db 0
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.end:
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db 0
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unknown:
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db "Unknown command", 0xd, 0xa, 0
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cmdhello:
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db "hello", 0
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hello:
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db "Hello world!", 0xd, 0xa, 0
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cmdecho:
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db "echo", 0
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