Post by thread:what is SKPNC and SKPZ?

Quite plain and simple, my question is what are the commands SKPNC and SKPZ? I see they are used in this macro but what do they do? I don't see them on any of my data sheets! {Quote hidden}>>sub_word_literal: macro aaa, lll >> >> movlw low (~(lll) + 1) >> addwf aaa+1, f >> movlw high ((~(lll) + 1) & h'ffff') >> skpnc >> addlw 1 >> skpnc >> skpz >> addwf aaa, f >> endm Thanks in advance for any info, Brian

Clewer,Brian <spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU> wrote: > what are the commands SKPNC and SKPZ? Brian: They're MPASM pseudo-ops... SKPNC ("Skip if No Carry") is equivalent to "BTFSC STATUS,C" and SKPZ ("Skip if Zero") is equivalent to "BTFSS STATUS,Z". -Andy === Andrew Warren - .....fastfwdKILLspam@spam@ix.netcom.com === === Fast Forward Engineering - Vista, California === === === === Custodian of the PICLIST Fund -- For more info, see: === === http://www.geocities.com/SiliconValley/2499/fund.html ===

> Quite plain and simple, my question is what are the commands SKPNC and SKPZ? > I see they are used in this macro but what do they do? I don't see them on > any of my data sheets! I think they are macros themselves that do "skip on no carry" and "skip on zero". Shorthand for "BTFSC STATUS, C" and "BTFSS STATUS, Z".

{Quote hidden}> >Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! > > > >>>sub_word_literal: macro aaa, lll >>> >>> movlw low (~(lll) + 1) >>> addwf aaa+1, f >>> movlw high ((~(lll) + 1) & h'ffff') >>> skpnc >>> addlw 1 >>> skpnc >>> skpz >>> addwf aaa, f >>> endm > > >Thanks in advance for any info, >Brian > > I took the description from MPALC.TXT included with the software. SKPZ: SKIP ON ZERO SKPNC: SKIP ON NO CARRY When I am not sure of an instruction, I run it with the simulator and give values to the different bits. It is important that each instruction you are using, you master them. Good luck with your project. Jean

"Clewer,Brian" <brian.clewerKILLspamTELEMATICS.COM> wrote: >Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! These are macros that are built into MPASM. Many people find them easier to type and more intuitive to read. SKPNC: skip if no carry = btfsc STATUS, C SKPZ: skip if zero = btfss STATUS, Z -- Bob Fehrenbach Wauwatosa, WI .....bfehrenbKILLspam.....execpc.com

>Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! > > > >>>sub_word_literal: macro aaa, lll >>> >>> movlw low (~(lll) + 1) >>> addwf aaa+1, f >>> movlw high ((~(lll) + 1) & h'ffff') >>> skpnc >>> addlw 1 >>> skpnc >>> skpz >>> addwf aaa, f >>> endm I'm not a PIC programmer but, I imagine they mean skip no carry and skip zero... RGDS Mike There is no a'priori reason that the ultimate truth will be interesting or even useful, those moments of frustration during philosophical debate would be replaced by the sheer terror which accompanies true knowledge.

At 04:34 PM 1/2/97 PST, you wrote: >Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! > SKPNC = BTFSC STATUS,C SKPZ = BTFSS STATUS,Z ____________________ Gonzalo Palarea EraseMEchalospam_OUTTakeThisOuTinfovia.com.gt

The instructions SKPZ, SKPNZ (Skip if ZERO flag is set/ Skip if ZERO flag is clear) SKPC, SKPNC (same, just CARRY) are pseudo-instructions that are understood by at least the Microchip compilers. The translate into instructions like BTFSC STATUS,3 BTFSS STATUS,3 If you look at the STATUS register, you'll find that the ZERO flag, and the CARRY flag (and some others I can recall off-hand) are mapped in that register. Sometime you want to take different actions depending on what state the STATUS flags are in, and these SKIP instructions are quite handy. E.g., you want to decrement a memory location IF it isn't already zero. TSTF mem_loc SKPZ DECF mem_loc,F (TSTF is another pseudocode that moves the memory file to itself, BUT this affects the ZERO flag) Hope it helps. Jan van der Watt [I saW ElviS - hE sAT beTWEen me AnD BIgFoOT oN thE UFo]

>Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! It's a typical redefinition of "btfsc STATUS,C" and "btfss STATUS,Z", it makes it easier to remember which way skips and which way doesn't. Cheers, Bob

At 04:34 PM 1/2/97 PST, you wrote: >Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! > SKPNC means 'Skip on No Carry' and SKPZ means 'Skip on Zero'. They are equivalent to the following: #define SKPNC BTFSC 3, 0 ; Skip on No Carry #define SKPZ BTFSS 3, 2 ; Skip on Zero The following can also be used: #define CLRC BCF 3, 0 ; Clear Carry #define SETC BSF 3, 0 ; Set Carry #define SKPC BTFSS 3, 0 ; Skip on Carry #define CLRDC BCF 3, 1 ; Clear Digit Carry #define SETDC BSF 3, 1 ; Set Digit Carry #define SKPDC BTFSS 3, 1 ; Skip on Digit Carry #define SKPNDC BTFSC 3, 1 ; Skip on No Digit Carry #define CLRZ BCF 3, 2 ; Clear Zero #define SETZ BSF 3, 2 ; Set Zero #define SKPNZ BTFSC 3, 2 ; Skip on Non Zero You can embed these mnemonics in the P16Cxx.INC file and make them available to all your programs automatically. You can probably come up with more if you like. The problem with these short cuts is just what you discovered. Other people who look at your code may not know how you have defined your mneumnics and get lost. They may make your code more readable to you, but maybe not so readable to others. It's your call whether you think this is a good practice or not. Hope that helps. DRC :->

At 04:34 PM 1/2/97 PST, you wrote: >Quite plain and simple, my question is what are the commands SKPNC and SKPZ? >I see they are used in this macro but what do they do? I don't see them on >any of my data sheets! > > > >>>sub_word_literal: macro aaa, lll >>> >>> movlw low (~(lll) + 1) >>> addwf aaa+1, f >>> movlw high ((~(lll) + 1) & h'ffff') >>> skpnc >>> addlw 1 >>> skpnc >>> skpz >>> addwf aaa, f >>> endm Hi Brian, You can check the MPASM for windows online help to get the answer. SKPNC = btfsc status,c ;Skip on No Carry SKPZ = btfss status,z ;Skip on Zero Jerry Meng, BA1FB ba1fbspam_OUTamsat.org http://www.srsnet.com/~ba1fb

D. R. Chicotel <@spam@PICLISTKILLspamMITVMA.MIT.EDU> wrote: > You can embed these mnemonics in the P16Cxx.INC file and make them > available to all your programs automatically. You can probably > come up with more if you like. The problem with these short cuts > is just what you discovered. Other people who look at your code may > not know how you have defined your mneumnics and get lost. D.R.: The pseudo-ops you listed (as well as the two that started this thread) are all built into MPASM already... There's no need to define them in an "include" file. Since they're already understood by MPASM, I don't think their use is particularly confusing. Just my opinion... I could be wrong. -Andy === Andrew Warren - KILLspamfastfwdKILLspamix.netcom.com === === Fast Forward Engineering - Vista, California === === === === Custodian of the PICLIST Fund -- For more info, see: === === http://www.geocities.com/SiliconValley/2499/fund.html ===

At 05:47 PM 1/2/97 -0800, you wrote: {Quote hidden}>D. R. Chicotel <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> wrote: > >> You can embed these mnemonics in the P16Cxx.INC file and make them >> available to all your programs automatically. You can probably >> come up with more if you like. The problem with these short cuts >> is just what you discovered. Other people who look at your code may >> not know how you have defined your mneumnics and get lost. > >D.R.: > >The pseudo-ops you listed (as well as the two that started this >thread) are all built into MPASM already... There's no need to >define them in an "include" file. > >Since they're already understood by MPASM, I don't think their use is >particularly confusing. > >Just my opinion... I could be wrong. > >-Andy > But they are not understood by MPASM for use with the 17Cxx parts. I was porting 16C5x code over to a 17Cxx part yesterday. Wish I had thought of defining these pseudo-ops as D.R. suggested instead of spenting 10 minutes doing a search/replace on all my skpxx instructions! Jim