avr: use provided polynomial.

avr/common/crc8.asm

@@ -8,31 +8,22 @@
 ; ***************************************************************************
 
 
-; ***************************************************************************
-; defines
-
-
-.equ CRC8_POLYNOMIAL   = 0x97 ; HD=4 up to 119 bytes, e.g. detects all 1 to 3 bit errors
-
-
-
 .cseg
 
 
 ; ---------------------------------------------------------------------------
+; @routine crc8Calc @global
 ; calc crc8 checksum using given polynomial
 ;
-; IN:
-; - X  : pointer to data to calc crc8 for
-; - r18: number of bytes to calc crc8 for
-; OUT:
-; - r16: crc8 checksum
-; - X  : point directly behind the checked area
-; MODIFIED REGS: R16, R17, R18, R19, R20, X
+; @return r16 crc8 checksum
+; @return X   points directly after last checked byte
+; @param X    pointer to data to calc crc8 for
+; @param r18  number of bytes to calc crc8 for
+; @param r19  polynomial to use
+; @clobbers: R16, R17, R18, R20, X
 
 crc8Calc:
-  ldi r16, 0xff              ; crc
-  ldi r19, CRC8_POLYNOMIAL
+  ldi r16, 0xff              ; start crc
   
 crc8Calc_loop1:
     ld r17, X+               ; running var
@@ -48,6 +39,7 @@ crc8Calc_l1:
     dec r18
   brne crc8Calc_loop1
   ret
+; @end