43 lines
800 B
NASM
43 lines
800 B
NASM
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; Loops over every character.
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; Multiplies current by 10
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; Adds [bx] - 0x30
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; add bx, 1
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parse_int:
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pusha
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; Contains the actual result
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mov ax, 0
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.loop:
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mov cl, [bx]
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cmp cl, 0x0 ; End on null
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je .end
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; If the character is invalid, stop here.
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cmp cl, 0x30
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jl .end
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cmp cl, 0x39
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jg .end
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; Multiply by 10
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mov cx, 10 ; NOT 0x10
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mul cx
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; Note: Has to be cx and not cl, otherwise it will be limited to 8-bits only
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mov cl, [bx]
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sub cl, 0x30
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mov ch, 0x0
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add ax, cx ; Use 16-bit addition
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add bx, 1 ; Next char
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jmp .loop
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.end:
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mov [result], ax
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popa
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ret
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result: dw 0
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