please dont rip this site

PIC Microcontoller Math Method

Multiply 16x8 bit from Dingbat

;--------------------------------------------------------------------+
;   Function: Math : Multiply 16bits by 8bits                        |
;--------------------------------------------------------------------|
;   Filename: M_MUL16x8.inc       |   Environment    : MPLAB         |
;   Version : 1                   |   Microcontroller: PIC16F8x*     |
;   Date    : 21/07/2003          |   OSC MHz/MIPS   : xx / xxx      |
;--------------------------------------------------------------------|
;   Author         : Dingbat                                         |
;   Company        : -                                               |
;   Files required : none                                            |
;--------------------------------------------------------------------|

; Unsigned 16*8 bit Multiply AA(16) * BB(8), Result (CC) is 24bit
; adapted from code found on www.piclist.com
;
; params 	
;	AA 0:1 (MSB:LSB) 	= number to multiply (16bit)
;	BB					= multiplier (8bit)
;   CC 0:3 (MSB:LSB)	= Product (24bit)
;
; Taking out the loops and inlining the code would save about 
; another 20-30 instructions

MUL16x8
	clrf	CC+0		;clear result
	clrf	CC+1		;
	clrf	CC+2		;
	movlw	.8		
	movwf	bitCount	;bit counter set @ number of bits in multiplier

mul_L1					;main loop here
	rlf		CC+2,f			;rotate result left (*2)
	rlf		CC+1,f			;
	rlf		CC+0,f			;
	bcf		CC+2,0			;clear LSB of result after rotation
	btfss	BB,7			;test msb of multipier
	goto	dontAdd			;if bit is clear then dont add
	movfw   AA+1      		;Add the 16 bits of AA to product
	addwf   CC+2,f      	;
	skpnc					;
	incf	CC+1,f			;
	movfw   AA				;
	addwf   CC+1,f      	;
	skpnc					;
	incf	CC+0,f			;
dontAdd
	rlf		BB,f			;rotate multiplier left
	decfsz	bitCount,f		;chk if finished all bits in multiplier
	goto	mul_L1

	return


+

Comments:

See also:


file: /Techref/microchip/math/mul/16x8-d.htm, 3KB, , updated: 2013/4/9 07:39, local time: 2020/2/19 20:02,
TOP NEW HELP FIND: 
34.204.183.113:LOG IN

 ©2020 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://massmind.org/techref/microchip/math/mul/16x8-d.htm"> PIC Microcontoller Math Method </A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

 

Welcome to massmind.org!

 

Welcome to massmind.org!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .