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;
;********************************************************************
; Binary To BCD Conversion Routine
; This routine converts a 16 Bit binary Number to a 5 Digit
; BCD Number. This routine is useful since PIC16C55 & PIC16C57
; have two 8 bit ports and one 4 bit port ( total of 5 BCD digits)
;
; The 16 bit binary number is input in locations H_byte and
; L_byte with the high byte in H_byte.
; The 5 digit BCD number is returned in R0, R1 and R2 with R0
; containing the MSD in its right most nibble.
;
; Performance :
; Program Memory : 35
; Clock Cycles : 885
;
;*******************************************************************;
;
count equ 16
temp equ 17
;
H_byte equ 10
L_byte equ 11
R0 equ 12 ; RAM Assignments
R1 equ 13
R2 equ 14
;
include "picreg.h"
;
B2_BCD bcf STATUS,0 ; clear the carry bit
movlw .16
movwf count
clrf R0
clrf R1
clrf R2
loop16 rlf L_byte
rlf H_byte
rlf R2
rlf R1
rlf R0
;
decfsz count
goto adjDEC
RETLW 0
;
adjDEC movlw R2
movwf FSR
call adjBCD
;
movlw R1
movwf FSR
call adjBCD
;
movlw R0
movwf FSR
call adjBCD
;
goto loop16
;
adjBCD movlw 3
addwf 0,W
movwf temp
btfsc temp,3 ; test if result > 7
movwf 0
movlw 30
addwf 0,W
movwf temp
btfsc temp,7 ; test if result > 7
movwf 0 ; save as MSD
RETLW 0
;
;********************************************************************
; Test Program
;*********************************************************************
main movlw 0FF
movwf H_byte
movwf L_byte ; The 16 bit binary number = FFFF
call B2_BCD ; After conversion the Decimal Number
; ; in R0,R1,R2 = 06,55,35
;
self goto self
;
org 1FF
goto main
;
END
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