crc16 calculator

[pebau]

'Check your calculated CRC:
'https://www.lammertbies.nl/comm/info/crc-calculation.html


GLOBAL index%
hex_telegram$= ""
OPTION MEMTYPE char
'--------------------------------
GLOBAL ch TYPE  uint16_t
GLOBAL data_pointer TYPE int

'-------------------------------------------'
' fuction definitions  ---------------------'
'-------------------------------------------'
FUNCTION crc16$(STRING param$)
LOCAL crc TYPE uint16_t  
LOCAL mask TYPE uint16_t
LOCAL poly TYPE uint16_t
crc =  DEC("FFFF")
mask = DEC("FFFF")
LOCAL crc$=""
length=LEN(param$)
data_pointer=1
poly = DEC("1021")

PRINT "CRC Input:",param$

WHILE (length >0)
   ch=ASC(MID$(param$,data_pointer,1))
   ch = ch << 8
   'PRINT "ch: ", HEX$(ch)
       FOR i=0 TO 7
          IF ((crc ^ ch) & DEC("8000")) > 0 THEN
               xor_flag=1
               'PRINT "XOR=1"
              ELSE  
               xor_flag=0
               'PRINT "XOR=0"
              ENDIF
          crc = crc << 1
          IF (xor_flag) THEN
              crc = crc ^ poly
              ENDIF
          ch = ch << 1      
   NEXT i
 
   data_pointer=data_pointer+1
   length=length-1
WEND

PRINT "Result(dec): ",crc
PRINT "Result(hex): ",HEX$(crc)
PRINT "Result(hex/inverted): ",HEX$(DEC("0xFFFF") ^crc)
PRINT (mask ^ crc) FORMAT "%04X" TO crc$
RETURN crc$
END FUNCTION

'----------------------------------------------------------'
' main program                                             '
'----------------------------------------------------------'
crc_input$="123456789"
crc_result$=crc16$(crc_input$)
PRINT "CRC: ",crc_result$



'How to compile:
'bacon64>./bacon -l -L. crc16_26.1.2017.bac
'Converting 'crc16_26.1.2017.bac'... done, 62 lines were processed in 0.067 seconds.
'Compiling 'crc16_26.1.2017.bac'... cc -c crc16_26.1.2017.bac.c
'cc -o crc16_26.1.2017 crc16_26.1.2017.bac.o -lbacon -lm -L. -lm -L.
'Done, program 'crc16_26.1.2017' ready.
'
'Test:
'bacon64>./crc16_26.1.2017
'CRC Input:123456789
'Result(dec): 10673
'Result(hex): 29B1
'Result(hex/inverted): D64E
'CRC: D64E

[joreveur]

Hi pebau
Nice
I checked on my computer and it's ok

CRC Input:123456789
Result(dec): 10673
Result(hex): 29B1
Result(hex/inverted): D64E
CRC: D64EI only added key=GETKEY

Regards

[pebau]

How is the performance compared to other program languages ?
Would be interesting ;-)
How could we optimize that code ? any idea ?

Best Regards,
Peter Bauer
www.bitkistl.com

[vovchik]

Dear Peter,

Nicely done. I have just eliminated some unneeded stuff and changed the MID$ for slightly more efficiency, I think. And all variables are now local, so the function is self-contained, and vars that get initialized as "" or 0 do not need to be set to those values (crc$ and data_pointer, for example).


' ------------------
FUNCTION CRC16$(STRING param$)
' ------------------
LOCAL data_pointer, i, length, xor_flag TYPE int
LOCAL ch, crc, mask, poly TYPE uint16_t
LOCAL crc$ TYPE STRING
crc = mask = USHRT_MAX
poly = DEC("1021")
length = LEN(param$)
PRINT "CRC Input:", param$
WHILE length DO
ch = param$[data_pointer]
ch = ch << 8
FOR i = 0 TO 7
xor_flag = IIF(((crc ^ ch) & DEC("8000")), 1, 0)
crc = crc << 1
IF xor_flag THEN
crc = crc ^ poly
END IF
ch = ch << 1  
NEXT i  
INCR data_pointer
DECR length
WEND
PRINT "Result(dec): ", crc
PRINT "Result(hex): ", HEX$(crc)
PRINT "Result(hex/inverted): ", HEX$(DEC("0xFFFF") ^ crc)
PRINT (mask ^ crc) FORMAT "%04X" TO crc$
RETURN crc$
END FUNCTION

' ***********************
' MAIN
' ***********************

PRINT "CRC: ", CRC16$("123456789")


With kind regards,
vovchik

[pebau]

Thank you for your help vovchik :-)
Without you and your friends I could not understand BaCon.
Here you can find some more nice tinkering (both hardware and software)
www.pearltrees.com/pebauer

Best Regards,
Peter