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Annotation of coherent/a/usr/src/misc/crc16.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Tables for the table-driven CRC16 algorithm.
                      3:  * This should be relatively uniform statistically.
                      4:  */
                      5: static unsigned short crctab1[] = {
                      6:        0000000,        0140301,        0140601,        0000500,
                      7:        0141401,        0001700,        0001200,        0141101,
                      8:        0143001,        0003300,        0003600,        0143501,
                      9:        0002400,        0142701,        0142201,        0002100
                     10: };
                     11: 
                     12: static unsigned short crctab2[] = {
                     13:        0000000,        0146001,        0154001,        0012000,
                     14:        0170001,        0036000,        0024000,        0162001,
                     15:        0120001,        0066000,        0074000,        0132001,
                     16:        0050000,        0116001,        0104001,        0043000
                     17: };
                     18: 
                     19: /*
                     20:  * Read a string return the hash value computed using CRC-16 methods.
                     21:  * usefull for various kinds of hashing including diff programs
                     22:  * and symbol tables.
                     23:  */
                     24: unsigned short
                     25: crc16(p)
                     26: register char *p;
                     27: {
                     28:        register unsigned char tmp, c;
                     29:        register unsigned short h;
                     30: 
                     31:        for(h = 0; c = *p; p++) {
                     32:                tmp = c ^ h;
                     33:                h = (h >> 8) ^ crctab1[tmp & 15] ^ crctab2[tmp >> 4];
                     34:        }
                     35:        return(h);
                     36: }

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