unsigned crc16_table[256] = {

    0x0000,0x1189,0x2312,0x329b,0x4624,0x57ad,0x6536,0x74bf,

    0x8c48,0x9dc1,0xaf5a,0xbed3,0xca6c,0xdbe5,0xe97e,0xf8f7,

    0x1891,0x0918,0x3b83,0x2a0a,0x5eb5,0x4f3c,0x7da7,0x6c2e,

    0x94d9,0x8550,0xb7cb,0xa642,0xd2fd,0xc374,0xf1ef,0xe066,

    0x3122,0x20ab,0x1230,0x03b9,0x7706,0x668f,0x5414,0x459d,

    0xbd6a,0xace3,0x9e78,0x8ff1,0xfb4e,0xeac7,0xd85c,0xc9d5,

    0x29b3,0x383a,0x0aa1,0x1b28,0x6f97,0x7e1e,0x4c85,0x5d0c,

    0xa5fb,0xb472,0x86e9,0x9760,0xe3df,0xf256,0xc0cd,0xd144,

    0x6244,0x73cd,0x4156,0x50df,0x2460,0x35e9,0x0772,0x16fb,

    0xee0c,0xff85,0xcd1e,0xdc97,0xa828,0xb9a1,0x8b3a,0x9ab3,

    0x7ad5,0x6b5c,0x59c7,0x484e,0x3cf1,0x2d78,0x1fe3,0x0e6a,

    0xf69d,0xe714,0xd58f,0xc406,0xb0b9,0xa130,0x93ab,0x8222,

    0x5366,0x42ef,0x7074,0x61fd,0x1542,0x04cb,0x3650,0x27d9,

    0xdf2e,0xcea7,0xfc3c,0xedb5,0x990a,0x8883,0xba18,0xab91,

    0x4bf7,0x5a7e,0x68e5,0x796c,0x0dd3,0x1c5a,0x2ec1,0x3f48,

    0xc7bf,0xd636,0xe4ad,0xf524,0x819b,0x9012,0xa289,0xb300,

    0xc488,0xd501,0xe79a,0xf613,0x82ac,0x9325,0xa1be,0xb037,

    0x48c0,0x5949,0x6bd2,0x7a5b,0x0ee4,0x1f6d,0x2df6,0x3c7f,

    0xdc19,0xcd90,0xff0b,0xee82,0x9a3d,0x8bb4,0xb92f,0xa8a6,

    0x5051,0x41d8,0x7343,0x62ca,0x1675,0x07fc,0x3567,0x24ee,

    0xf5aa,0xe423,0xd6b8,0xc731,0xb38e,0xa207,0x909c,0x8115,

    0x79e2,0x686b,0x5af0,0x4b79,0x3fc6,0x2e4f,0x1cd4,0x0d5d,

    0xed3b,0xfcb2,0xce29,0xdfa0,0xab1f,0xba96,0x880d,0x9984,

    0x6173,0x70fa,0x4261,0x53e8,0x2757,0x36de,0x0445,0x15cc,

    0xa6cc,0xb745,0x85de,0x9457,0xe0e8,0xf161,0xc3fa,0xd273,

    0x2a84,0x3b0d,0x0996,0x181f,0x6ca0,0x7d29,0x4fb2,0x5e3b,

    0xbe5d,0xafd4,0x9d4f,0x8cc6,0xf879,0xe9f0,0xdb6b,0xcae2,

    0x3215,0x239c,0x1107,0x008e,0x7431,0x65b8,0x5723,0x46aa,

    0x97ee,0x8667,0xb4fc,0xa575,0xd1ca,0xc043,0xf2d8,0xe351,

    0x1ba6,0x0a2f,0x38b4,0x293d,0x5d82,0x4c0b,0x7e90,0x6f19,

    0x8f7f,0x9ef6,0xac6d,0xbde4,0xc95b,0xd8d2,0xea49,0xfbc0,

    0x0337,0x12be,0x2025,0x31ac,0x4513,0x549a,0x6601,0x7788

};


/* compute 16 bit CCITT crc using the table */

unsigned crc16(unsigned crc,unsigned b)

{

    unsigned ret = crc16_table[(b ^ crc) & 0xff] ^ (crc >> 8);

    return ret;

}

(polynom reverse=0,data reverce=0) 1B2B
(polynom reverse=0,data reverce=1) CAC6
(polynom reverse=1,data reverce=0) 9956
(polynom reverse=1,data reverce=1) B7DD

  
unsigned short crc = 0;
crc = crc16(crc, 0x30);
printf("CRC=0x%X\n"m crc);

// 0x1021
function [15:0] fn_crc_ccitt;
input[15:0] crc_current;
input[7:0] data;
begin
fn_crc_ccitt[0]  = data[4] ^ data[0] ^ crc_current[8] ^ crc_current[12];
fn_crc_ccitt[1]  = data[5] ^ data[1] ^ crc_current[9] ^ crc_current[13];
fn_crc_ccitt[2]  = data[6] ^ data[2] ^ crc_current[10] ^ crc_current[14];
fn_crc_ccitt[3]  = data[7] ^ data[3] ^ crc_current[11] ^ crc_current[15];
fn_crc_ccitt[4]  = data[4] ^ crc_current[12];
fn_crc_ccitt[5]  = data[5] ^ data[4] ^ data[0] ^ crc_current[8] ^ crc_current[12] ^ crc_current[13];
fn_crc_ccitt[6]  = data[6] ^ data[5] ^ data[1] ^ crc_current[9] ^ crc_current[13] ^ crc_current[14];
fn_crc_ccitt[7]  = data[7] ^ data[6] ^ data[2] ^ crc_current[10] ^ crc_current[14] ^ crc_current[15];
fn_crc_ccitt[8]  = data[7] ^ data[3] ^ crc_current[0] ^ crc_current[11] ^ crc_current[15];
fn_crc_ccitt[9]  = data[4] ^ crc_current[1] ^ crc_current[12];
fn_crc_ccitt[10] = data[5] ^ crc_current[2] ^ crc_current[13];
fn_crc_ccitt[11] = data[6] ^ crc_current[3] ^ crc_current[14];
fn_crc_ccitt[12] = data[7] ^ data[4] ^ data[0] ^ crc_current[4] ^ crc_current[8] ^ crc_current[12] ^ crc_current[15];
fn_crc_ccitt[13] = data[5] ^ data[1] ^ crc_current[5] ^ crc_current[9] ^ crc_current[13];
fn_crc_ccitt[14] = data[6] ^ data[2] ^ crc_current[6] ^ crc_current[10] ^ crc_current[14];
fn_crc_ccitt[15] = data[7] ^ data[3] ^ crc_current[7] ^ crc_current[11] ^ crc_current[15];
end     
endfunction     


// 0x8408
function [7:0] fn_reverse_data;
input[7:0] data;
integer    i;
begin
for(i=0;i<8;i=i+1)  fn_reverse_data[i]    = data[7-i];
end     
endfunction     

function [15:0] fn_reverse_inverse_crc;
input[15:0] crc;
integer    i;
begin
for(i=0;i<16;i=i+1)  fn_reverse_inverse_crc[i]    = ~crc[15-i];
end     
endfunction

        0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
    0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
    0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
    0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
    0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
    0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
    0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
    0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
    0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
    0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
    0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
    0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
    0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
    0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
    0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
    0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
    0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
    0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
    0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
    0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
    0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
    0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
    0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
    0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
    0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
    0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
    0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
    0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
    0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
    0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
    0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
    0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78