8-bit Divide: Difference between revisions
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The following code divide two 8-bit integers (range 0...255) and outputs a 16-bit result using only real calculation, no lockup table so the size of the code is very small. | The following code divide two 8-bit integers (range 0...255) and outputs a 16-bit result using only real calculation, no lockup table so the size of the code is very small. | ||
< | <pre> | ||
;8-bit divide | ;8-bit divide | ||
;by Bregalad | ;by Bregalad | ||
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ldy Res2 | ldy Res2 | ||
rts | rts | ||
</ | </pre> | ||
Revision as of 04:12, 11 September 2014
The following code divide two 8-bit integers (range 0...255) and outputs a 16-bit result using only real calculation, no lockup table so the size of the code is very small.
;8-bit divide ;by Bregalad ;Enter with A = Dividend, Y=Divisor ;Output with YA = (1/256)*(A/Y) Division sta Dvd ;Stores divident sty Dvs ;Stores divisor lda #$00 sta Res ;Clear result ldy #$10 ;The loop is for 16-bit result - asl Dvd rol A ;Shift divisor in 1 bit cmp Dvs ;Check if fractional dividend is greater than divisor bcc + sbc Dvs ;Substract (C is always set) + rol Res ;Shift result (1 if substation was done, 0 otherwise) rol Res2 dey bne - lda Res ldy Res2 rts
