please dont rip this site

PIC Microcontroller Bit Math Method

Converting a 3-bit number to a 8-bit mask

From: Mike Keitz. There is a trick method that works for 4 bits. It replaces a 2-bit number in a variable with a 4-bit mask: 

        incf    BitP, W  ;W = 0001 0010 0011 0100 
        btfsc   BitP, 1  ;If 0 or 1, result is almost correct now. 
        iorwf   BitP, F  ;BitP = [0000] [0001] 0011 0111 
        incf    BitP, F  ;BitP = 0001 0010 0100 1000

It could be the core of an 8-bit routine thus: 

; Convert 3-bit number (0-7) in INDEX to a 8-bit mask (00000001 ... 
; 10000000) in BitP. 
        movfw   INDEX 
        andlw   b'00000011'     ;Start with half of the mask. 
        movwf   BitP 
        incf    BitP, W         ;The 4-bit converter 
        btfsc   BitP, 1 
        iorwf   BitP, F 
        incf    BitP, F 
        btfsc   INDEX, 2        ;Is it high 4 bits? 
        swapf   BitP, F

file: /Techref/scenix/lib/math/bit/mask.htm, 1KB, , updated: 2004/6/10 14:40, local time: 2025/10/30 18:31,
TOP NEW HELP FIND: 
216.73.216.139,10-3-157-36:LOG IN
 ©2025 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/scenix/lib/math/bit/mask.htm"> PIC Microcontroller Bit Math Method Converting a 3-bit number to a 8-bit mask</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!

 
Quick, Easy and CHEAP! RCL-1 RS232 Level Converter in a DB9 backshell
Ashley Roll has put together a really nice little unit here. Leave off the MAX232 and keep these handy for the few times you need true RS232!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .