# 8-bit Divide

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The following code divide two 8-bit integers (range 0...255) and outputs a 16-bit result in fixed point 8.8 format. It is only using real calculations, no lookup table, thus the size of the code is very small.

;8-bit divide ;by Bregalad ;Enter with A = Dividend, Y=Divisor ;Output with YX = (A/Y) << 8, A = remainder Division sta Dvd ;Stores dividend sty Dvs ;Stores divisor lda #$00 ;A must be zero before entering the loop below. sta ResHi ;Clear result, setting up a ring counter ldy #$01 ;by initializing the result to $0001. sty Res ;When the 1 gets shifted out, we're done - asl Dvd rol A ;Shift in 1 bit of dividend bcs + ;If carry is set, the dividend is already greater cmp Dvs ;Check if fractional dividend is greater than divisor bcc ++ + sbc Dvs ;Subtract (C is always set) sec ;Necessary if we reached here via the `bcs +` above ++ rol Res ;Shift result (1 if subtraction was done, 0 otherwise) rol ResHi bcc - ldx Res ldy ResHi rts