please dont rip this site

SX Microcontroller Bit Math Method

Setting bit number X

Tracy Smith says

Here are a couple of ideas for getting 1<<TestBit (10 cycles):
	clr	W
	snb	TestBit.2
	mov	W, #%11111100
	add	TestBit, W

	mov	W, ++TestBit
	snb	TestBit.1
	or	TestBit, W

	inc	TestBit

	snb	C
	swap	TestBit

another way (7 cycles [including the call])

	and	W, #7
	add	PC, W
	retw	#1
	retw	#2
	retw	#4
	retw	#8
	retw	#$10
	retw	#$20
	retw	#$40
	retw	#$80

or probably more to the point

	mov	W, Rb
	mov	portb_shadow, W

	sb	TestBit.2
	swap	portb_swadow

	sb	TestBit.0
	rl	portb_shadow

	mov	W, #%10000000
	sb	TestBit.1
	mov	W, #%00100000

	and	portb_shadow, W

	snb	Z
	jmp	_the_bit_is_set


Kevin Blain says:

	clrf    mask    ; empty the mask

; a file called bit contains the 0 to 7 value of the bit position

	inc	bit	; make it 1 to 8, so decfsz works nicely
	setb	C	; set the carry flag. This will be rotated in 'bit' times
	rl	mask
	decsz	bit	; skip out after 'bit' times.
	jmp	loop
.....               ; rest of code...

Of course, it would be good to ensure that bit is not greater than 7 when
entering the routine.


file: /Techref/scenix/lib/math/bit/setbit_sx.htm, 1KB, , updated: 2004/6/10 13:40, local time: 2024/2/27 08:06,

 ©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=""> SX Microcontroller Bit Math Method - Setting bit number X</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!


Welcome to!