please dont rip this site

PIC Microcontoller Math Method

Multiply 16x16 bit signed from malinSTOPspam at TakeThisOuTonspec.co.uk

;malin@onspec.co.uk
;signed multiply of a2:a1 with b2:b1 leaving result in res4:res3:res2:res1
;	These 8 variables need to be defined, as does neg_flag
;
;	Program length	64 lines
;	time 134 to 248 cycles
;	This program looks at the lsb of a1 to decide whether to add b1 to res2
;
;   and b2 to res3, with appropriate carrys
;	It then looks at the lsb of a2 to decide whether to add b1 to res3 and 
;	b2 to res4, again with appropriate carrys.
;	The rotates then only have to be done 8 times
;
;	This is uses slightly more program but takes a little less time than 
;	a routine that performs one 16 bit addition per rotate and 16 rotates
;
;	Multiple byte addition routine from Microchip AN617
;	Result registers used as loop counter from Bob Fehrenbach & Scott Dattalo
;


	clrf    res4
	clrf	res3
	clrf    res2
	movlw	0x80
	movwf	res1		

	clrf	neg_flag

	btfss   a2,7
	goto    a_pos
	comf    a2,f
	comf	a1,f
	incf	a1,f
	btfsc	status, zero
	incf    a2,f
	incf	neg_flag, f
a_pos
	btfss   b2,7
	goto    nextbit
	comf    b2,f
	comf    b1,f 
	incf    b1,f 
	btfsc   status, zero
	incf    b2,f
	incf	neg_flag, f

nextbit
	rrf		a2,f
	rrf		a1,f

	btfss	status, carry
	goto	nobit_l
	movf	b1,w
	addwf	res2,f

	movf	b2, w
	btfsc	status, carry
	incfsz	b2, w	
	addwf	res3, f	
	btfsc	status, carry
	incf	res4, f
	bcf		status, carry
	
nobit_l	
	btfss	a1, 7
	goto	nobit_h
	movf	b1,w
	addwf	res3,f
	btfsc	status, carry
	incf	res4,f
	movf	b2,w		
	addwf	res4,f
nobit_h
	rrf		res4,f
	rrf		res3,f
	rrf		res2,f
	rrf		res1,f

	btfss   status, carry
	goto	nextbit
	btfss   neg_flag, 0
	goto 	no_invert		

	comf    res4,f
	comf    res3,f
	comf    res2,f
	comf	res1,f

	incf    res1,f
	btfsc   status,zero
	incf	res2,f
	btfsc   status,zero
	incf    res3,f
	btfsc   status,zero
	incf    res4,f
no_invert



file: /Techref/microchip/math/mul/16x16malin.htm, 2KB, , updated: 2002/10/28 11:08, local time: 2024/10/31 15:44,
TOP NEW HELP FIND: 
18.216.43.190:LOG IN
©2024 PLEASE DON'T RIP! THIS SITE CLOSES OCT 28, 2024 SO LONG AND THANKS FOR ALL THE FISH!

 ©2024 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://ecomorder.com/Techref/microchip/math/mul/16x16malin.htm"> PIC Microcontoller Math Method Multiply 16x16 bit Signed from malin</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 a nice message (short messages are blocked as spam) 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 ecomorder.com!

 

Welcome to ecomorder.com!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .