8-bit Divide: Difference between revisions
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;Output with YA = (1/256)*(A/Y) | ;Output with YA = (1/256)*(A/Y) | ||
Division | Division | ||
sta Dvd ;Stores | sta Dvd ;Stores dividend | ||
sty Dvs ;Stores divisor | sty Dvs ;Stores divisor | ||
lda #$00 | lda #$00 | ||
| Line 17: | Line 17: | ||
cmp Dvs ;Check if fractional dividend is greater than divisor | cmp Dvs ;Check if fractional dividend is greater than divisor | ||
bcc + | bcc + | ||
sbc Dvs ; | sbc Dvs ;Subtract (C is always set) | ||
+ rol Res ;Shift result (1 if | + rol Res ;Shift result (1 if subtraction was done, 0 otherwise) | ||
rol Res2 | rol Res2 | ||
dey | dey | ||
Revision as of 18:48, 9 October 2014
The following code divide two 8-bit integers (range 0...255) and outputs a 16-bit result using only real calculation, no lookup 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 dividend 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 ;Subtract (C is always set) + rol Res ;Shift result (1 if subtraction was done, 0 otherwise) rol Res2 dey bne - lda Res ldy Res2 rts
