Thanks for the code, but when I input 0x64, I get 0x90 as an output.
In the meantime, I try to figure it out at this end.
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Thanks for the code, but when I input 0x64, I get 0x90 as an output.
In the meantime, I try to figure it out at this end.
Charles Linquist
|
This is what I'm using.
If input = $64
Output = $36
;-----------------------------------------------------------------
The code:
Mult32:
asm
;clear X
clrf _XU
clrf _XH
clrf _XM
clrf _XL
;shift A by 1 position left
rlncf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
;[repeat the shift-routine]
rlncf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
;move A to X
movff _AU,_XU
movff _AH,_XH
movff _AM,_XM
movff _AL,_XL
;[repeat the shift-routine]
rlncf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
;[repeat the shift-routine]
rlncf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
;[repeat the shift-routine]
rlncf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
;add A to X
movf _AL,w
addwf _XL,f ;ignore Carry
movf _AM,w
addwfc _XM,w
movf _AH,w
addwfc _XH,w
movf _AU,w
addwfc _XU,w
;[repeat the shift-routine]
rlncf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
;[repeat the add-routine]
movf _AL,w
addwf _XL,f ;ignore Carry
movf _AM,w
addwfc _XM,w
movf _AH,w
addwfc _XH,w
movf _AU,w
addwfc _XU,w
endasm
Charles Linquist
|
Charles,
You have a timer running at 100 hz, and you're dividing those interrupts by 100 to count seconds. Then later you want to multiply the seconds times 100.
Why not just count the interrupts directly? Then you have the Sec*100 already (plus fractional secs), and you can DIV32 100 that number for the seconds, or keep a separate count for the seconds and no DIV or MUL required.
<br>
DT
|
Darrel,
Actually, I have 1Khz interrupt running. I really didn't want to use it because I really like routines that run often to be very short. Since this is for an SNMP trap (an ERROR has ocurred), the timer tick value will be output something like once a year. That is why I wanted to do the multiply only when necessary.
Maybe I'm getting too stingy with the 8722's time!
Charles Linquist
|
OK, that sounds reasonable enough.
So back to BigWumpus' code.
The rlncf's are a problem because it rotates the high bit around to the low bit. What needs to be done is rotate a 0 into the Low bit, and the High bit to the carry.
bcf STATUS, C
rlcf _AL,f
rlcf _AM,f
rlcf _AH,f
rlcf _AU,f
and the addwfc's need to go to F (file) instead of W. Here's the corrected code...Or, Here's my little spin on it.Code:asm ;clear X clrf _XU clrf _XH clrf _XM clrf _XL ;shift A by 1 position left bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f ;[repeat the shift-routine] bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f ;move A to X movff _AU,_XU movff _AH,_XH movff _AM,_XM movff _AL,_XL ;[repeat the shift-routine] bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f ;[repeat the shift-routine] bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f ;[repeat the shift-routine] bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f ;add A to X bcf STATUS, C movf _AL,w addwfc _XL,f movf _AM,w addwfc _XM,F movf _AH,w addwfc _XH,F movf _AU,w addwfc _XU,F ;[repeat the shift-routine] bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f ;[repeat the add-routine] bcf STATUS, C movf _AL,w addwfc _XL,f movf _AM,w addwfc _XM,F movf _AH,w addwfc _XH,F movf _AU,w addwfc _XU,F endasmHTH,Code:gosub Mult32 ;______________________________ Mult32: asm call ShiftA call ShiftA ; *4 movff _AU,_XU ; move A to X movff _AH,_XH movff _AM,_XM movff _AL,_XL call ShiftA call ShiftA call ShiftA ; *32 call AddAX ;add A to X call ShiftA ; *64 call AddAX ;add A to X return ;________________________________________________ ShiftA ; shift A by 1 position left bcf STATUS, C rlcf _AL,f rlcf _AM,f rlcf _AH,f rlcf _AU,f return AddAX ; add A to X movf _AL,w addwf _XL,F ;ignore Carry movf _AM,w addwfc _XM,F movf _AH,w addwfc _XH,F movf _AU,w addwfc _XU,F return endasm
DT
|
Thank you Darrel,
Your routine works as advertised. Now I can get on with the rest of the details of "SIMPLE" Network Management Protocol. HA!
Charles Linquist
|
And I'll defer that to BigWumpus,
Great idea, just needed a little debugging.
DT
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