Post by thread:Oring bits within a byte

Good morning - I'm trying to do the following: I have a byte (let's call it TEMP), and I'm trying to logically 'OR' together 3 of the bits within the byte. ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) There doesn't seem to be any bit wise 'or' functions. Any ideas on how to implement this? Thanks in advance Daniel Najemy - Data General Corporation, Numaliine Power Systems

Najemy, Daniel wrote: > > I have a byte (let's call it TEMP), and I'm trying to logically 'OR' > together 3 of the bits within the byte. > > ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) > > Any ideas on how to implement this? bcf nResultByte, bResultBit ; assume result bit is zero movf nTemp,W andlw (1<<3 + 1<<4 + 1<< 5) ; w := 00xyz0000 btfss STATUS,Z bsf nResultByte, bResultBit ; sets result bit I think this should do it. If all the bits 3, 4 and 5 are zero, W := z, the zero flag is set and the result bit is not

On Mon, 26 Jan 1998 11:04:59 -0500 "Najemy, Daniel" <spam_OUTDNajemyTakeThisOuTIMPS0014.US.DG.COM> writes: >Good morning - > >I'm trying to do the following: > >I have a byte (let's call it TEMP), and I'm trying to logically 'OR' >together 3 of the bits within the byte. > >ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) > How about something like this... movlw b'0011100' ; Set up the mask andwf temp,0 ; Leave selected bits in w, others 0 bz AllZeroes ; go deal with them all being zeroes ... ; Code to be executed if one or more bits were set Harold _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]

Mask the three bits using AND. Test if resultant byte is 0 or greater than 0. If it is greater than 0, then the result should be set to 1. Kieran ---------- From: Najemy, Daniel[SMTP:.....DNajemyKILLspam@spam@IMPS0014.US.DG.COM] Sent: 26 January 1998 16:04 To: PICLISTKILLspamMITVMA.MIT.EDU Subject: Oring bits within a byte Good morning - I'm trying to do the following: I have a byte (let's call it TEMP), and I'm trying to logically 'OR' together 3 of the bits within the byte. ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) There doesn't seem to be any bit wise 'or' functions. Any ideas on how to implement this? Thanks in advance Daniel Najemy - Data General Corporation, Numaliine Power Systems

Najemy, Daniel wrote: > > Good morning - > > I'm trying to do the following: > > I have a byte (let's call it TEMP), and I'm trying to logically 'OR' > together 3 of the bits within the byte. > > ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) > > There doesn't seem to be any bit wise 'or' functions. Any ideas on how > to implement this? Yeah, we had this discussion a few months back. Using the nomenclature then, here's a way to or two arbitrary bits in two aribtrary registers and place the result in another arbitray register: e.g. C.bit_C = A.bit_a | B.bit_b: BCF C,bit_c BTFSS A,bit_a BTFSC B,bit_b BSF C,bit_c Which could be extended for three or more bits. However in your case, there's even a simpler trick: CLRF RESULT ;Assume all three bits are low MOVF TEMP,W ANDLW (1<<3) | (1<<4) | (1<<5) SKPZ INCF RESULT ;At least one bit was high Scott -- __o I buy pizza instead of gas. \< (*)/(*)

Daniel, Best I can do of the top of my head is:- RLF TEMP, W IORWF TEMP, F RLF TEMP, W IORWF TEMP, F OR'ed result in TEMP,5 Trashes TEMP and W 4 cycles I'm sure somebody can do it better Steve Lawther ______________________________ Reply Separator _________________________________ Subject: Oring bits within a byte Author: PC:.....DNajemyKILLspam.....IMPS0014.US.DG.COM at INTERNET-HUSKY Date: 26/01/98 16:27 Good morning - I'm trying to do the following: I have a byte (let's call it TEMP), and I'm trying to logically 'OR' together 3 of the bits within the byte. ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) There doesn't seem to be any bit wise 'or' functions. Any ideas on how to implement this? Thanks in advance Daniel Najemy - Data General Corporation, Numaliine Power Systems

Steve Lawther wrote: > > Daniel, > > Best I can do of the top of my head is:- > > RLF TEMP, W > IORWF TEMP, F > RLF TEMP, W > IORWF TEMP, F > > OR'ed result in TEMP,5 > Trashes TEMP and W > 4 cycles > > I'm sure somebody can do it better > > Steve Lawther Good idea Steve, but how 'bout: RLF TEMP,W ANDLW ((1<<3) | (1<<4) | (1<<5))<<1 ADDLW 0xf0 RLF RESULT,F Scott

Najemy, Daniel wrote: > Good morning - > > I'm trying to do the following: > > I have a byte (let's call it TEMP), and I'm trying to logically 'OR' > together 3 of the bits within the byte. > > ie. RESULT = (TEMP,3) or (TEMP,4) or (TEMP,5) > > There doesn't seem to be any bit wise 'or' functions. Any ideas on how > to implement this? > > Thanks in advance > > Daniel Najemy - Data General Corporation, Numaliine Power Systems if you are talking about doing or with higher with lower nibbles this is what you can do. cblock 00 lower result endc movf temp,w ; temp is your byte example 00001111 swapf temp,w ; now temp is 11110000 movwf lower ; save swaped nibbles iorwf temp,w ; do or w with temp w is lower and temp is higher movwf result ; save it in result movwf portb ; display the result on portb it is not tested if this is what you need I can make it work and send it to you. Andre Abelian ========================================== = http://www.compufire.com = = EraseMEandrespam_OUTTakeThisOuTcompufire.com = = mcu-engineeringspam_OUTcompufire.com = = Andre Abelian: Engine Electronics, Inc.= = Tel 909-589-5485 Fax 909-598-5695 = ==========================================