This is an example for 0x068FB0 to 0x0503 division (a2 a1 a0 /b1 b0), results will be in d2 d1 d0
A tutorial and a description about how this CORDIC division method it works can be found at www.piclist.com
init
movlw 0x06 ;d2 d1 d0 = 430000/b1 b0
movwf a2
movlw 0x8F
movwf a1
movlw 0xB0
movwf a0
movlw 0x05
movwf b1
movlw 0x03
movwf b0
call divv24
goto fin
;**********************************************************************
; d2 d1 d0 = a2 a1 a0 / b1 b0
divv24
clrf b2
movf b0,F ; test division to null
btfss STATUS,Z
goto test_z_ok
movf b1,F
btfsc STATUS,Z
return
test_z_ok
movlw 0x01
movwf temp0
clrf temp1
clrf temp2
clrf d0 ; init result
clrf d1
clrf d2
shift_24
bcf STATUS,C ; rotate to left up b2,7 =1 in this case
rlf temp0,F ; multiplication counter
rlf temp1,F
rlf temp2,F
bcf STATUS,C
rlf b0,F
rlf b1,F
rlf b2,F
btfss b2,7 ; 430000/b2b1b0
; work faster if shift it is according with a2a1a0,
; in this case a2=0x06 so I replace last command with this
; btfss b2,2 ; 430000/b2b1b0
goto shift_24
wdh32
call store_a
call sub32 ; ok substract
btfsc STATUS,C ; a1-b1 <0
goto partial ; if a1-b1>0 then countx
call restore
goto rest
partial
movf temp0,W ; add temp0 to result
addwf d0,F
btfsc STATUS,C
incf d1,F
movf temp1,W
addwf d1,F
btfsc STATUS,C ; btfsc STATUS,C
incf d2,F
movf temp2,W
addwf d2,F
rest
bcf STATUS,C
rrf b2,F
rrf b1,F ; rotate to right for b and t then repeat
rrf b0,F
bcf STATUS,C
rrf temp2,F
rrf temp1,F
rrf temp0,F
btfss STATUS,C ; if temp0<>0 then wdh32
goto wdh32
return
sub32
movf b0,W
subwf a0,F
movf b1,W
btfss STATUS,C
incfsz b1,W
subwf a1,F
movf b2,W
btfss STATUS,C
incfsz b2,W
subwf a2,F
return
store_a
movf a0,W
movwf count0
movf a1,W
movwf count1
movf a2,W
movwf count2
return
restore
movf count0,W
movwf a0
movf count1,W
movwf a1
movf count2,W
movwf a2
return
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Last updated January, 2010