847 lines
15 KiB
NASM
847 lines
15 KiB
NASM
; Clear the screen and set cursor position to (0, 0)
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clear:
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push ax
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mov ax, 03h
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int 10h
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mov ax, 200h
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xor dx, dx
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int 10h
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pop ax
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ret
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; Detect display. Video mode 0 if no display,
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; 1 if monochrome display, 2 if colour display
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detect_video:
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push ax
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mov ax, 30h
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and ax, DETECTED_HARDWARE
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cmp ax, 20h
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mov [VIDEO_MODE], 2
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cmp ax, 30h
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mov [VIDEO_MODE], 1
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pop ax
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ret
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; Print terminated string
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;
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; DS:SI - Pointer on string
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print_string:
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pusha
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mov cx, 1
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mov bh, 0Fh
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print_string.print:
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lodsb
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cmp al, 0
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je print_string.finish
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call print_symbol
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jmp print_string.print
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print_string.finish:
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popa
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ret
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; Split user input on 4 parts by space
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split_str_4_space:
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push ax
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push bx
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push cx
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push dx
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push si
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reset_buf cmd.userinput_com, ARGUMENT_BUFFER_SIZE
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reset_buf cmd.userinput_arg1, ARGUMENT_BUFFER_SIZE
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reset_buf cmd.userinput_arg2, ARGUMENT_BUFFER_SIZE
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reset_buf cmd.userinput_arg3, ARGUMENT_BUFFER_SIZE
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mov bx, cmd.userinput_com
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mov si, cmd.userinput_buf
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split_str_4_space.lp:
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mov al, [si]
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mov [bx], al
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inc bx
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inc si
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cmp byte [si], ' '
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je split_str_4_space.change_part
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cmp byte [si], 0
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je split_str_4_space.rtt
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jmp split_str_4_space.lp
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split_str_4_space.rtt:
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pop si
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pop dx
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pop cx
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pop bx
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pop ax
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mov byte [split_str_4_space.part], 1
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ret
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split_str_4_space.change_part:
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cmp byte [split_str_4_space.part], 1
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je split_str_4_space.change_part.part1
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cmp byte [split_str_4_space.part], 2
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je split_str_4_space.change_part.part2
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cmp byte [split_str_4_space.part], 3
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je split_str_4_space.change_part.part3
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cmp byte [split_str_4_space.part], 4
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je split_str_4_space.change_part.part4
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split_str_4_space.part db 1
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split_str_4_space.change_part.part1:
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inc [split_str_4_space.part]
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mov bx, cmd.userinput_arg1
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inc si
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jmp split_str_4_space.lp
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split_str_4_space.change_part.part2:
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inc [split_str_4_space.part]
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mov bx, cmd.userinput_arg2
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inc si
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jmp split_str_4_space.lp
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split_str_4_space.change_part.part3:
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inc [split_str_4_space.part]
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mov bx, cmd.userinput_arg3
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inc si
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jmp split_str_4_space.lp
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split_str_4_space.change_part.part4:
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jmp split_str_4_space.rtt
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; Print symbol
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;
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; AL - symbol
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print_symbol:
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pusha
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xor bx, bx
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mov cx, 1
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mov ah, 0Eh
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int 10h
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popa
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ret
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; Reset buffer
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; DS:SI - buffer
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; CX - Length
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reset_buffer:
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push si
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push cx
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reset_buffer.lp:
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mov byte [ds:si], 0
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inc si
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dec cx
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cmp cx, 0
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jne reset_buffer.lp
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reset_buffer.nd:
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pop cx
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pop si
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ret
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; Input string
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;
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; DS:SI - Pointer on buffer
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; CX - Buffer length
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; ---
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; AX - Last pressed key
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input_string:
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push bx
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mov bx, 0
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input_string.reset_buffer:
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push si
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push cx
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input_string.reset_buffer.lp:
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mov byte [ds:si], 0
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inc si
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dec cx
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cmp cx, 0
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jne input_string.reset_buffer.lp
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input_string.reset_buffer.nd:
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pop cx
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pop si
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input_string.processing:
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xor ah, ah
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int 16h
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cmp al, 0Dh
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je input_string.ent
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cmp al, 08h
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je input_string.backspace
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cmp al, 03h
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je input_string.ctrlc
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call print_symbol
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mov [ds:si+bx], al
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inc bx
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cmp bx, cx
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je input_string.ent
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jmp input_string.processing
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input_string.backspace:
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cmp bx, 0
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je input_string.processing
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mov ah, 0Eh
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int 10h
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mov al, ' '
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int 10h
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mov al, 08h
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int 10h
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dec bx
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mov byte [ds:si+bx], 0
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jmp input_string.processing
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input_string.ent:
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pop bx
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xor ah, ah
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print ln
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ret
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input_string.ctrlc:
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jmp input_string.ent
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; Compare strings
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;
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; DS:SI - Pointer on first string
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; DS:BX - Pointer on second string
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; ---
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; Carry flag - 1 if strings are not equal
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compare_strings:
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push ax
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push bx
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push si
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compare_strings.comp:
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lodsb
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cmp [bx], al
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jne compare_strings.not_equal
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cmp al, 0
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je compare_strings.equal
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inc bx
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jmp compare_strings.comp
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compare_strings.equal:
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clc
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jmp compare_strings.return
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compare_strings.not_equal:
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stc
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jmp compare_strings.return
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compare_strings.return:
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pop si
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pop bx
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pop ax
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ret
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; Copies string
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;
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; DS:SI - Pointer on memory from where copy
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; DS:BX - Pointer on memory where copy
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copy_string:
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push si
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push bx
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push ax
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copy_string.lp:
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lodsb
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cmp al, 0
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je copy_string.ed
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mov byte [bx], al
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inc bx
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jmp copy_string.lp
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copy_string.ed:
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pop ax
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pop bx
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pop si
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ret
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; Calculate len of string
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;
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; DS:SI - Pointer on string
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; ---
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; AX - Len of string
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calculate_string_len:
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push si
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xor ax, ax
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push ax
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calculate_string_len.lp:
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lodsb
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cmp al, 0
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je calculate_string_len.ed
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pop ax
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inc ax
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push ax
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jmp calculate_string_len.lp
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calculate_string_len.ed:
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pop ax
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pop si
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ret
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; ------------------------------------------------------------------
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; os_print_digit -- Displays contents of AX as a single digit
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; Works up to base 37, ie digits 0-Z
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; IN: AX = "digit" to format and print
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os_print_digit:
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pusha
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cmp ax, 9 ; There is a break in ASCII table between 9 and A
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jle .digit_format
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add ax, 'A'-'9'-1 ; Correct for the skipped punctuation
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.digit_format:
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add ax, "0" ; 0 will display as '0', etc.
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mov ah, 0Eh ; May modify other registers
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int 10h
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popa
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ret
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; ------------------------------------------------------------------
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; os_print_1hex -- Displays low nibble of AL in hex format
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; IN: AL = number to format and print
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os_print_1hex:
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pusha
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and ax, 0Fh ; Mask off data to display
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call os_print_digit
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popa
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ret
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; Print AL in hex
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;
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; AL - Number to print
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os_print_2hex:
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pusha
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push ax ; Output high nibble
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shr ax, 4
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call os_print_1hex
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pop ax ; Output low nibble
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call os_print_1hex
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popa
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ret
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; Print AX in hex
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;
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; AX - Number to print
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print_hex:
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pusha
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push ax ; Output high byte
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mov al, ah
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call os_print_2hex
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pop ax ; Output low byte
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call os_print_2hex
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popa
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ret
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; Print values of registers to screen
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;
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; AX, BX, CX, DX, SI, DI, ES, DS, SS, FLAGS - Registers to print
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print_registers:
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pushf
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push ss
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push ds
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push es
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push di
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push si
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push dx
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push cx
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push bx
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print print_registers.axd
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call print_hex
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print print_registers.h
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pop ax
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print print_registers.bxd
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call print_hex
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print print_registers.h, ln
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pop ax
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print print_registers.cxd
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call print_hex
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print print_registers.h
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pop ax
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print print_registers.dxd
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call print_hex
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print print_registers.h, ln
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pop ax
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print print_registers.sid
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call print_hex
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print print_registers.h
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pop ax
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print print_registers.did
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call print_hex
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print print_registers.h, ln
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pop ax
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print print_registers.esd
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call print_hex
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print print_registers.h
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pop ax
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print print_registers.dsd
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call print_hex
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print print_registers.h, ln
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pop ax
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print print_registers.ssd
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call print_hex
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print print_registers.h
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pop ax
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print print_registers.fd
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call print_hex
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print print_registers.h, ln
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ret
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; ------------------------------------------------------------------
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; os_string_to_int -- Convert decimal string to integer value
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; IN: SI = string location (max 5 chars, up to '65536')
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; OUT: AX = number
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string_to_int:
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pusha
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mov ax, si ; First, get length of string
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call os_string_length
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add si, ax ; Work from rightmost char in string
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dec si
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mov cx, ax ; Use string length as counter
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mov bx, 0 ; BX will be the final number
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mov ax, 0
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; As we move left in the string, each char is a bigger multiple. The
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; right-most character is a multiple of 1, then next (a char to the
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; left) a multiple of 10, then 100, then 1,000, and the final (and
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; leftmost char) in a five-char number would be a multiple of 10,000
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mov word [.multiplier], 1 ; Start with multiples of 1
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.loop:
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mov ax, 0
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mov byte al, [si] ; Get character
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sub al, 48 ; Convert from ASCII to real number
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mul word [.multiplier] ; Multiply by our multiplier
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add bx, ax ; Add it to BX
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push ax ; Multiply our multiplier by 10 for next char
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mov word ax, [.multiplier]
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mov dx, 10
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mul dx
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mov word [.multiplier], ax
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pop ax
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dec cx ; Any more chars?
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cmp cx, 0
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je .finish
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dec si ; Move back a char in the string
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jmp .loop
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.finish:
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mov word [.tmp], bx
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popa
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mov word ax, [.tmp]
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ret
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.multiplier dw 0
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.tmp dw 0
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os_string_length:
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pusha
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mov bx, ax ; Move location of string to BX
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mov cx, 0 ; Counter
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.more:
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cmp byte [bx], 0 ; Zero (end of string) yet?
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je .done
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inc bx ; If not, keep adding
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inc cx
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jmp .more
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.done:
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mov word [.tmp_counter], cx ; Store count before restoring other registers
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popa
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mov ax, [.tmp_counter] ; Put count back into AX before returning
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ret
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.tmp_counter dw 0
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; Convert unsigned int to string
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;
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; AX - Num to convert
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; SI - Where save string
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; ---
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; SI - Pointer to string with converted num
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int_to_string:
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push cx
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push bx
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push di
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push ax
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mov cx, 0
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mov bx, 10 ; Set BX 10, for division and mod
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mov di, si ; Get our pointer ready
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int_to_string.push:
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mov dx, 0
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div bx ; Remainder in DX, quotient in AX
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inc cx ; Increase pop loop counter
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push dx ; Push remainder, so as to reverse order when popping
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test ax, ax ; Is quotient zero?
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jnz int_to_string.push ; If not, loop again
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int_to_string.pop:
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pop dx ; Pop off values in reverse order, and add 48 to make them digits
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add dl, '0' ; And save them in the string, increasing the pointer each time
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mov [di], dl
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inc di
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dec cx
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jnz int_to_string.pop
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mov byte [di], 0 ; Zero-terminate string
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mov si, di
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pop ax
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pop di
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pop bx
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pop cx
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ret
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; Find file on disk from filename
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; BX - filename
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; ---
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; SI - filename position in table
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; CF - 1 if file not exist
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find_file:
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push bx
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push ax
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push cx
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mov cx, TABLE_SIZE
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mov si, filetable
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add si, 4
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mov [find_file.fn_offset], bx
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find_file.lp:
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mov bx, [find_file.fn_offset]
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call compare_strings
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jnc find_file.found
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dec cx
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cmp cx, 0
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je find_fileret
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mov bx, 12
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; len si
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xor ax, ax
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sub bx, ax
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xchg ax, bx
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add si, ax
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add si, 4
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; mov al, [si]
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; cmp al, 0
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je find_fileret
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jmp find_file.lp
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find_file.found:
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sub si, 4
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pop cx
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pop ax
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pop bx
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clc
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ret
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find_fileret:
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xor si, si
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pop cx
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pop ax
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pop bx
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stc
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ret
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find_file.fn_offset dw 0
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; Remove file
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; BX - filename
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; ---
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; CF - 1 if file not exist
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remove_file:
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push ax
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push si
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push bx
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call find_file
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jc remove_file.rtt
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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add si, 2
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mov dword [si], 0
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pop bx
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pop si
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pop ax
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ret
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remove_file.rtt:
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pop bx
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pop si
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pop ax
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ret
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; Append file to FS table
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; AL - Cylinder
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; AH - Head
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; BL - sector
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; BH - Size
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; SI - Pointer on name (Max 11 chars)
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append_file:
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pusha
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mov [append_file.cylinder], al
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mov [append_file.head], ah
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mov [append_file.sector], bl
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mov [append_file.size], bh
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mov word [append_file.name_os], si
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mov cx, TABLE_SIZE
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mov si, filetable+4
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|
append_file.lp:
|
|
cmp byte [si], 0
|
|
je append_file.write
|
|
add si, 16
|
|
dec cx
|
|
cmp cx, 0
|
|
je append_file.cannot
|
|
jmp append_file.lp
|
|
append_file.nd:
|
|
popa
|
|
ret
|
|
append_file.write:
|
|
sub si, 4
|
|
mov al, [append_file.cylinder]
|
|
mov ah, [append_file.head]
|
|
mov bl, [append_file.sector]
|
|
mov bh, [append_file.size]
|
|
mov byte [si], al
|
|
mov byte [si+1], ah
|
|
mov byte [si+2], bl
|
|
mov byte [si+3], bh
|
|
add si, 4
|
|
mov bx, si
|
|
mov si, word [append_file.name_os]
|
|
call copy_string
|
|
clc
|
|
call write_table
|
|
jmp append_file.nd
|
|
append_file.cannot:
|
|
stc
|
|
jmp append_file.nd
|
|
|
|
append_file.cylinder db 0
|
|
append_file.head db 0
|
|
append_file.sector db 0
|
|
append_file.size db 0
|
|
append_file.name_os dw 0
|
|
|
|
; Rename file in FS table
|
|
; SI - Filename
|
|
; BX - To what filename change
|
|
rename_file:
|
|
pusha
|
|
mov word [rename_file.fst], si
|
|
mov word [rename_file.snd], bx
|
|
mov bx, si
|
|
call find_file
|
|
jc rename_file.notfound
|
|
add si, 4
|
|
push si
|
|
reset_buf si, 12
|
|
pop si
|
|
mov bx, si
|
|
mov si, word [rename_file.snd]
|
|
call copy_string
|
|
rename_file.notfound:
|
|
popa
|
|
ret
|
|
|
|
rename_file.fst dw 0
|
|
rename_file.snd dw 0
|
|
|
|
; Read file and load to memory
|
|
; SI - File in FS table
|
|
; BX - Where load
|
|
load_file:
|
|
pusha
|
|
mov ah, 02h
|
|
mov al, [si+3]
|
|
mov dl, [BOOT_DRIVE]
|
|
mov ch, [si]
|
|
mov dh, [si+1]
|
|
mov cl, [si+2]
|
|
int 13h
|
|
popa
|
|
ret
|
|
|
|
; loadoffset dw 0
|
|
|
|
; Write file and load to memory
|
|
; SI - File in FS table
|
|
; CX - Where
|
|
save_file:
|
|
pusha
|
|
popa
|
|
ret
|
|
|
|
; Read FS table from disk
|
|
read_table:
|
|
pusha
|
|
mov ah, 02h
|
|
mov al, 2
|
|
mov dl, [BOOT_DRIVE]
|
|
mov ch, 0
|
|
mov dh, 0
|
|
mov cl, 3
|
|
mov bx, filetable
|
|
int 13h
|
|
popa
|
|
ret
|
|
|
|
; Write FS table to disk
|
|
write_table:
|
|
pusha
|
|
mov ah, 03h
|
|
mov al, 2
|
|
mov dl, [BOOT_DRIVE]
|
|
mov ch, 0
|
|
mov dh, 0
|
|
mov cl, 3
|
|
mov bx, filetable
|
|
int 13h
|
|
popa
|
|
ret
|
|
|
|
|
|
wait_key:
|
|
mov ah, 11h
|
|
int 16h
|
|
|
|
jnz wait_key.key_pressed
|
|
|
|
hlt
|
|
jmp wait_key
|
|
|
|
wait_key.key_pressed:
|
|
mov ah, 10h
|
|
int 16h
|
|
ret
|
|
|
|
; Copy memory from A to B
|
|
; SI - A
|
|
; BX - B
|
|
; CX - Number of bytes to copy
|
|
copy_memory:
|
|
pusha
|
|
copy_memory.lp:
|
|
cmp cx, 0
|
|
je copy_memory.nd
|
|
lodsb
|
|
mov [bx], al
|
|
inc bx
|
|
dec cx
|
|
jmp copy_memory.lp
|
|
copy_memory.nd:
|
|
popa
|
|
ret
|
|
|
|
; Get cursor position
|
|
; ---
|
|
; DL - X
|
|
; DH - Y
|
|
get_cursor_pos:
|
|
push ax
|
|
push cx
|
|
push bx
|
|
mov ah, 03h
|
|
xor bx, bx
|
|
int 10h
|
|
pop bx
|
|
pop cx
|
|
pop ax
|
|
ret
|
|
|
|
; Set cursor position
|
|
; DL - X
|
|
; DH - Y
|
|
set_cursor_pos:
|
|
push ax
|
|
push bx
|
|
mov ah, 02h
|
|
xor bx, bx
|
|
int 10h
|
|
pop bx
|
|
pop ax
|
|
ret
|
|
|
|
; Print values of registers and halt cpu
|
|
dbg_halt_cpu:
|
|
call print_registers
|
|
call halt_cpu
|
|
|
|
; Shows goodbye message and stops the CPU
|
|
halt_cpu:
|
|
print ln, goodbye
|
|
cli
|
|
hlt
|