Kongsberg Seapath 320, Installation Manual, Page: 124 / 152

Seapath 320
108 M300-62/rev.2
crc = ~crc;
data = crc;
crc = (crc << 8) | ((data >> 8) & 0xff);
return crc;
}
Fortran code:
SUBROUTINE blkcrc(inbuffer, len, crc)
INTEGER*2 len, i , bit
INTEGER*4 crc, data, poly
CHARACTER inbuffer*(*)
poly = 16#8408
crc = 16#FFFF
data = 0
IF (len.EQ.0) THEN
crc = 0
RETURN
END IF
DO i = 1, len
data = ICHAR(inbuffer(i:i))
DO bit = 1, 8
data = IAND(data,16#FF)
IF (IAND(crc,16#01).EQ.(IAND(data,16#01))) THEN
crc = ISHL(crc,-1)
ELSE
crc = ISHL(crc,-1)
crc = IEOR(crc, poly)
END IF
data = ISHL(data,-1)
END DO
END DO
data = IEOR(crc,16#FFFF)
crc = IOR(ISHL(data,8),IAND(ISHL(data,-8),16#FF))
END