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Annotation of sbbs/sbbs2/fido/crc16.c, revision 1.1

1.1     ! root        1: /* CRC16.C */
        !             2: 
        !             3: /* 16-bit CRC routines */
        !             4: 
        !             5: #include "smblib.h"
        !             6: 
        !             7: /****************************************************************************/
        !             8: /* Updates 16-bit "rcrc" with character 'ch'                                */
        !             9: /****************************************************************************/
        !            10: void ucrc16(uchar ch, ushort *rcrc) {
        !            11:     ushort i, cy;
        !            12:     uchar nch=ch;
        !            13:  
        !            14: for (i=0; i<8; i++) {
        !            15:     cy=*rcrc & 0x8000;
        !            16:     *rcrc<<=1;
        !            17:     if (nch & 0x80) *rcrc |= 1;
        !            18:     nch<<=1;
        !            19:     if (cy) *rcrc ^= 0x1021; }
        !            20: }
        !            21: 
        !            22: /****************************************************************************/
        !            23: /* Returns 16-crc of string (not counting terminating NULL)                 */
        !            24: /****************************************************************************/
        !            25: ushort crc16(char *str)
        !            26: {
        !            27:     int     i=0;
        !            28:     ushort  crc=0;
        !            29: 
        !            30: ucrc16(0,&crc);
        !            31: while(str[i])
        !            32:     ucrc16(str[i++],&crc);
        !            33: ucrc16(0,&crc);
        !            34: ucrc16(0,&crc);
        !            35: return(crc);
        !            36: }
        !            37: 

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