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Within these pages, you can find many useful pieces of code mostly in assembly for the Microchip PIC micro controller family. A lot of people have spend many hours trying to put the bits and bytes together. If the code is NOT written by a member of the PCB Heaven community, then a link will be added above the code with the original website that this code was found.
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View code
24 bit integer
Author: Scott Dattalo
This code was originally located @ http://www.piclist.com
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;==========================================================================
; brSQRT24
;
; Calculates the square root of a twentyfour bit number using the
; binary restoring method.
;
; Result in ACCaHI:ACCaLO
; Input in ACCcLO:ACCdHI:ACCdLO
; Test ACCbLO:ACCcHI
; Counter in ACCbHI
;
; 40 words long, uses 8 bytes RAM (inc. 3 holding 24-bit input).
;
;--------------------------------------------------------------------------
brSQRT24:
clrf ACCaHI,f ;
clrf ACCaLO,f ;
clrf ACCcHI,f ;
clrf ACCbLO,w ;
movlw .12 ;
movwf ACCbHI ; (6 cycle intro, 8 incl. call)
ShftUp: rlcf ACCdLO,f ; Shift input up 2 places.
rlcf ACCdHI,f ; (33 cycles per loop if bit is 0)
rlcf ACCcLO,f ; (29 cycles per loop if bit is 1)
rlcf ACCcHI,f ;
rlcf ACCbLO,f ;
rlcf ACCdLO,f ;
rlcf ACCdHI,f ;
rlcf ACCcLO,f ;
rlcf ACCcHI,f ;
rlcf ACCbLO,f ;
rlcf ACCaLO,f ; Shift root-so-far up by two and append
rlcf ACCaHI,f ; ... '01'.
rlcf ACCaLO,f ;
rlcf ACCaHI,f ;
bcf ACCaLO,1 ;
bsf ACCaLO,0 ;
SubTest:movfp ACCaLO,WREG ;
subwf ACCcHI,f ;
movfp ACCaHI,WREG ;
subwfb ACCbLO,f ;
btfsc ALUSTA,C ;
goto Set1
movfp ACCaLO,WREG ; Restore the remainder.
addwf ACCcHI,f ; ... (the current bit is 0).
movfp ACCaHI,WREG ;
addwfc ACCbLO,f ;
goto Set0 ;
Set1: bsf ACCaLO,1 ;
Set0: rrcf ACCaHI,f ;
rrcf ACCaLO,f ;
bcf ACCaHI,7 ;
BitLoop:decfsz ACCbHI,f ;
goto ShftUp
return |
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