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       1                 :            : /*
       2                 :            :  *      linux/lib/crc-ccitt.c
       3                 :            :  *
       4                 :            :  *      This source code is licensed under the GNU General Public License,
       5                 :            :  *      Version 2. See the file COPYING for more details.
       6                 :            :  */
       7                 :            : 
       8                 :            : #include <linux/types.h>
       9                 :            : #include <linux/module.h>
      10                 :            : #include <linux/crc-ccitt.h>
      11                 :            : 
      12                 :            : /*
      13                 :            :  * This mysterious table is just the CRC of each possible byte. It can be
      14                 :            :  * computed using the standard bit-at-a-time methods. The polynomial can
      15                 :            :  * be seen in entry 128, 0x8408. This corresponds to x^0 + x^5 + x^12.
      16                 :            :  * Add the implicit x^16, and you have the standard CRC-CCITT.
      17                 :            :  */
      18                 :            : u16 const crc_ccitt_table[256] = {
      19                 :            :         0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
      20                 :            :         0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
      21                 :            :         0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
      22                 :            :         0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
      23                 :            :         0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
      24                 :            :         0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
      25                 :            :         0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
      26                 :            :         0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
      27                 :            :         0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
      28                 :            :         0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
      29                 :            :         0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
      30                 :            :         0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
      31                 :            :         0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
      32                 :            :         0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
      33                 :            :         0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
      34                 :            :         0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
      35                 :            :         0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
      36                 :            :         0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
      37                 :            :         0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
      38                 :            :         0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
      39                 :            :         0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
      40                 :            :         0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
      41                 :            :         0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
      42                 :            :         0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
      43                 :            :         0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
      44                 :            :         0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
      45                 :            :         0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
      46                 :            :         0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
      47                 :            :         0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
      48                 :            :         0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
      49                 :            :         0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
      50                 :            :         0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
      51                 :            : };
      52                 :            : EXPORT_SYMBOL(crc_ccitt_table);
      53                 :            : 
      54                 :            : /**
      55                 :            :  *      crc_ccitt - recompute the CRC for the data buffer
      56                 :            :  *      @crc: previous CRC value
      57                 :            :  *      @buffer: data pointer
      58                 :            :  *      @len: number of bytes in the buffer
      59                 :            :  */
      60                 :          0 : u16 crc_ccitt(u16 crc, u8 const *buffer, size_t len)
      61                 :            : {
      62         [ #  # ]:          0 :         while (len--)
      63                 :          0 :                 crc = crc_ccitt_byte(crc, *buffer++);
      64                 :          0 :         return crc;
      65                 :            : }
      66                 :            : EXPORT_SYMBOL(crc_ccitt);
      67                 :            : 
      68                 :            : MODULE_DESCRIPTION("CRC-CCITT calculations");
      69                 :            : MODULE_LICENSE("GPL");