Hi
I've made very good use of the code posted on your site so I'd like to give my thanks to the many contributers from whome I have learnt loads and who have save me a lot of time and head-scratching.
By way of thanks, I offer the following adaptation of Tony Nixons 24x24 bit division routine. I have expanded it to perform 48x24 bit division. While a little lardier than Nikolai Golovchenko's routine, it uses big-ended format (my preference) and provides a remainder (unfortunetly at the cost of a bit more ram). Anyway, I hope this may save someone a bit of time, as mine has been. Thanks all.
Code:
;************************************************************************** ;Div4824U ;Inputs: ; Dividend - Dividend:6 (0 - least significant!) ; Divisor - Test:3 (0 - least significant!) ;Temporary: ; Counter - Count ; Shift - Shift:6 ;Output: ; Quotient - Dividend:6 (0 - least significant!) ; Remainder- Rem:3 (0 - least significant!) ; ;Adaptation of 24x24 division by Tony Nixon with corrections ;by Frank Finster 3/15/2005. ;Code adapted by Andy Lee ;01-Sep-2006 Original version ;************************************************************************** Div4824U: ;--------------------------------------------------- ; SUBROUTINE - 48 by 24 BIT DIVISION movlw 48 movwf Count movff Dividend+0, Shift+0 movff Dividend+1, Shift+1 movff Dividend+2, Shift+2 movff Dividend+3, Shift+3 movff Dividend+4, Shift+4 movff Dividend+5, Shift+5 clrf Dividend+0 clrf Dividend+1 clrf Dividend+2 clrf Dividend+3 clrf Dividend+4 clrf Dividend+5 clrf Rem+2 clrf Rem+1 clrf Rem+0 dloop bcf STATUS, C rlcf Shift+0 rlcf Shift+1 rlcf Shift+2 rlcf Shift+3 rlcf Shift+4 rlcf Shift+5 rlcf Rem+0 rlcf Rem+1 rlcf Rem+2 movf Test+2, w subwf Rem+2, w btfss STATUS, Z bra nochk movf Test+1,w subwf Rem+1,w btfss STATUS, Z bra nochk movf Test+0,w subwf Rem+0,w nochk btfss STATUS, C bra nogo movf Test+0,w subwf Rem+0 btfsc STATUS, C bra nodec_remainM decf Rem+1, f movf Rem+1, w xorlw 0xff btfsc STATUS, Z decf Rem+2, f nodec_remainM movf Test+1, w subwf Rem+1, f btfss STATUS, C decf Rem+2, f movf Test+2, w subwf Rem+2, f bsf STATUS, C nogo rlcf Dividend+0 rlcf Dividend+1 rlcf Dividend+2 rlcf Dividend+3 rlcf Dividend+4 rlcf Dividend+5 decfsz Count, f goto dloop return
Comments:
Lewis Paul Lineberger of Alternate Energies Says:
I've provided a version of this code that fixes an overflow error, illustrated by+
0x34631A9FC / 0xDD39E9. Also, the code is provided for PIC12/PIC16 assembly. Thanks so much for the original work! See
http://www.piclist.com/techref/member/LPL-AEA-Z85/index.htm
file: /Techref/microchip/math/div/48by24al.htm, 3KB, , updated: 2009/5/1 12:19, local time: 2024/11/22 19:59,
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