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. | ||
< | <source lang="6502tasm"> | ||
;8-bit divide | ;8-bit divide | ||
;by Bregalad | ;by Bregalad | ||
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ldy Res2 | ldy Res2 | ||
rts | rts | ||
</source> | |||
</ | |||
Revision as of 09:19, 24 August 2013
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.
<source lang="6502tasm">
- 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 </source>
