Code:
+;************************************************************************** ;Div4824U ;Inputs: ; x - x:6 (x) (0 - least significant!) ; y - Test:3 (y) (0 - least significant!) ;Temporary: ; Counter - Count ; Shift - Shift:6 (mathint) ;Output: ; Quotient - x:6 (x) (0 - least significant!) ; Remainder- Rem:3 (0 - least significant!) ; ;Adaptation to PIC 12/16 Assembly and error fix of code by Frank Finster 3/15/2005 ;by Lewis Lineberger 4/24/2009 ;Fixes overrun in Rem+2 when upper bit of y+2 and Rem+2 are set, but Rem+2 is still ;less than y+2. Overrun is illustrated by 0x34631A9FC / 0xDD39E9. ;Adaptation of 24x24 division by Tony Nixon with corrections ;PIC18 assembly instructions in comments for easy adaptation. ;by Frank Finster 3/15/2005. ;Code adapted by Andy Lee ;01-Sep-2006 Original version ;************************************************************************** Div4824U ;--------------------------------------------------- ; SUBROUTINE - 48 by 24 BIT division movlw d'48' movwf Count ; movff x+0, Shift+0 movf x+0, W movwf mathint+0 ; movff x+1, Shift+1 movf x+1, W movwf mathint+1 ; movff x+2, Shift+2 movf x+2, W movwf mathint+2 ; movff x+3, Shift+3 movf x+3, W movwf mathint+3 ; movff x+4, Shift+4 movf x+4, W movwf mathint+4 ; movff x+5, Shift+5 movf x+5, W movwf mathint+5 clrf x+0 clrf x+1 clrf x+2 clrf x+3 clrf x+4 clrf x+5 clrf Rem+2 clrf Rem+1 clrf Rem+0 dloop bcf STATUS, C rlf mathint+0, F rlf mathint+1, F rlf mathint+2, F rlf mathint+3, F rlf mathint+4, F rlf mathint+5, F rlf Rem+0, F rlf Rem+1, F rlf Rem+2, F btfsc STATUS, C ; overrun goto subtract movf y+2, w subwf Rem+2, w btfss STATUS, Z goto nochk ;bra nochk movf y+1,w subwf Rem+1,w btfss STATUS, Z goto nochk ;bra nochk movf y+0,w subwf Rem+0,w nochk btfss STATUS, C ; Rem >= y goto nogo ;bra nogo subtract movf y+0,w subwf Rem+0, F btfsc STATUS, C goto nodec_remainM ;bra nodec_remainM decf Rem+1, f movf Rem+1, w xorlw 0xff btfsc STATUS, Z decf Rem+2, f nodec_remainM movf y+1, w subwf Rem+1, f btfss STATUS, C decf Rem+2, f movf y+2, w subwf Rem+2, f bsf STATUS, C nogo rlf x+0, F rlf x+1, F rlf x+2, F rlf x+3, F rlf x+4, F rlf x+5, F decfsz Count, f goto dloop return
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