38 lines
835 B
NASM
38 lines
835 B
NASM
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; data in dx
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print_hex:
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pusha
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mov cx, 0 ; index var
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hex_loop:
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cmp cx, 4 ; loop 4 times
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je end
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; 1) convert last char of 'dx' to ascii
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mov ax, dx ; ax is working register
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and ax, 0x000f ; 0x1234 -> 0x0004
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add al, 0x30 ; add 0x30 to N to convert it to ascii "n"
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cmp al, 0x39 ; if > 9, add extra 8 to represent a-f
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jle step2
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add al, 7 ; A is ascii 64 instead of 58, 65-58 = 7
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step2:
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; 2) get correct pos of string to place char
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; bx <- base address + string length - index
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mov bx, HEX_OUT + 5
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sub bx, cx ; cx: index
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mov [bx], al ; copy ascii char on al to pos pointed by bx
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ror dx, 4 ; 1234 - 4123 - 3412 - 2341 - 1234
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add cx, 1
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jmp hex_loop
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end:
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mov bx, HEX_OUT
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call print
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popa
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ret
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HEX_OUT:
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db '0x0000', 0 ; reserve memory for string
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