a.borowski@student.qut.edu.au shares this code:
http://alborowski.tk These chunks of code convert a binary number to 'bastard hex format' (NOTE TO PICLIST PERSON: If the word 'bastard' offends you, feel free to substitute borowski :-)EG d'255' will become ff (lower case), and bhf'73' will become 115. This is useful for EPROM programmers and the like, where you wish to send binary data to the PIC and back, but don't want your data accidently triggering any of the PIC's commands. Simply encode your data in BHF, send it to the PIC, which will decode it and process it.
I hope this is useful to someone...
BHF2BIN ; In: BHF1,BHF2 Out: BIN ;Working on BHF1: clrf BIN clrf W movf BHF1, 0 ; put BHF 1 into W register sublw d'96' ; ASCII char just before 'a' btfss STATUS,0 ; check to see if we have a letter or a number GOTO letBHF1 GOTO numBHF1 letBHF1 ;Code here is executed if we have a letter for BHF1 movlw d'87' subwf BHF1,0 ; get rid of the ASCII offset movwf BIN ; put the high nibble in BIN GOTO DoBHF2 numBHF1 ;Code here is executed if we have a number for BHF1 movlw d'48' subwf BHF1,0 ; get rid of the ASCII offset movwf BIN ; put the high nibble in BIN DoBHF2 ; this code takes care of the second BHf to bin nibble clrf W movf BHF2, 0 ; put BHF 2 into W register sublw d'96' ; ASCII char just before 'a' btfss STATUS,0 ; check to see if we have a letter or a number GOTO letBHF2 GOTO numBHF2 letBHF2 ;Code here is executed if we have a letter for BHF2 movlw d'87' subwf BHF2,0 ; get rid of the ASCII offset GOTO ShiftIn numBHF2 ;Code here is executed if we have a number for BHF2 movlw d'48' subwf BHF2,0 ; get rid of the ASCII offset ShiftIn bcf STATUS,0 ; get rid of any carry that could screw up the bitshift movwf Temp ; save out 2nd nibble in temp to prevent errors swapf Temp, 1 ;shift nibble to high nibble bcf STATUS,0 ; get rid of any carry that could screw up the bitshift ; All this tricky bit shifting merges the 2 nibbles gained from decoding BHF1 and BHF2 ; into a single binary byte rlf Temp,1 rlf BIN,1 rlf Temp,1 rlf BIN,1 rlf Temp,1 rlf BIN,1 rlf Temp,1 rlf BIN,1 movf BIN,0 ; put the result in W for debugging RETURN BIN2BHF ; this command wil encode a byte into bastard hex format. In: BIN Out: BHF1,BHF2 clrw clrf BHF1 clrf BHF2 bcf STATUS,0 ; get rid of any carry that could screw up the bitshift rrf BIN,1 rrf BHF2,1 rrf BIN,1 rrf BHF2,1 rrf BIN,1 rrf BHF2,1 rrf BIN,1 rrf BHF2,1 swapf BHF2,1 ; fix up annoying bug movf BIN, 0 movwf BHF1 ; put BHF nibble in place ;Now, to enocde in ASCII movf BHF1, 0; put BHF1 into W for debugging movf BHF2,0 ; put BHF2 into W for debugging movlw d'10' ; put 10 in W subwf BHF1, 0 clrw ; W is cleared btfsc STATUS,0 ; test if we have a number or a letter - next command is skipped if we have a number addlw d'39' addlw d'48' ; subtract 10 for hex addwf BHF1,1 movf BHF1,0 ; put BHF1 in W for debugging ;OK, BHF 1 is encoded bcf STATUS,0 ; clear any carry (as if that could make a difference) clrw ; Wipe W movf BHF2,0 ; put BHF2 into W for debugging movlw d'10' ; put 10 in W subwf BHF2, 0 clrw ; W is cleared btfsc STATUS,0 ; test if we have a number or a letter - next command is skipped if we have a number addlw d'39' addlw d'48' ; subtract 10 for hex addwf BHF2,1 movf BHF2,0 ; put BHF2 in W for debugging RETURN