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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
16 bit successive approximation for the 17c43
Author: Andy David
This code was originally located @ http://www.piclist.com
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;==========================================================================
; SQRT16
;
; Calculates the square root of a sixteen bit number by successive
; approximation.
;
;
; Input in ACCaHI:ACCaLO
;
; Output in ACCbHI
;
; Also uses ACCbLO and ACCcHI.
;
;--------------------------------------------------------------------------
SQRT16:
movlw 0x80 ;
movpf WREG,ACCbLO ; set up walking tester bit.
clrf ACCbHI,w ;
movlw 0x08 ;
movpf WREG,ACCcHI ;
tstest: movfp ACCbLO,WREG ; set bit for testing.
iorwf ACCbHI,WREG ;
movpf WREG,ACCbHI ;
mulwf ACCbHI ; square the current estimate.
movfp ACCaLO,WREG ; compare PRODH:PRODL with ACCaHI:ACCaLO
subwf PRODL,WREG ;
movfp ACCaHI,WREG ;
subwfb PRODH,WREG ;
btfss ALUSTA,C ; If the result is <= input,
goto nxtbit ; ... keep this bit set.
movfp ACCbLO,WREG ; Result was > input, so reset
xorwf ACCbHI,f ; ... bit to zero.
nxtbit: rrncf ACCbLO,f ; rotate tester bit right.
decfsz ACCcHI,f ;
goto tstest ;
return |
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