uint8_t crc8(uint8_t *block, uint16_t length) {
    uint8_t b, xcrc=0;
    uint16_t t;
    for (t=0; t<length; t++) {
        xcrc^=block[t];
        for (b=0; b<8; b++) if (xcrc&1) xcrc=(xcrc>>1)^0x8c; else xcrc>>=1;
    }
    return(xcrc);
}

uint16_t crc16(uint16_t seed, uint16_t length, uint8_t *block) {
    const uint16_t tCRC16[256] = {
        0x0000, 0xc1c0, 0x81c1, 0x4001, 0x01c3, 0xc003, 0x8002, 0x41c2, 0x01c6, 0xc006, 0x8007, 0x41c7, 0x0005, 0xc1c5, 0x81c4, 0x4004,
        0x01cc, 0xc00c, 0x800d, 0x41cd, 0x000f, 0xc1cf, 0x81ce, 0x400e, 0x000a, 0xc1ca, 0x81cb, 0x400b, 0x01c9, 0xc009, 0x8008, 0x41c8,
        0x01d8, 0xc018, 0x8019, 0x41d9, 0x001b, 0xc1db, 0x81da, 0x401a, 0x001e, 0xc1de, 0x81df, 0x401f, 0x01dd, 0xc01d, 0x801c, 0x41dc,
        0x0014, 0xc1d4, 0x81d5, 0x4015, 0x01d7, 0xc017, 0x8016, 0x41d6, 0x01d2, 0xc012, 0x8013, 0x41d3, 0x0011, 0xc1d1, 0x81d0, 0x4010,
        0x01f0, 0xc030, 0x8031, 0x41f1, 0x0033, 0xc1f3, 0x81f2, 0x4032, 0x0036, 0xc1f6, 0x81f7, 0x4037, 0x01f5, 0xc035, 0x8034, 0x41f4,
        0x003c, 0xc1fc, 0x81fd, 0x403d, 0x01ff, 0xc03f, 0x803e, 0x41fe, 0x01fa, 0xc03a, 0x803b, 0x41fb, 0x0039, 0xc1f9, 0x81f8, 0x4038,
        0x0028, 0xc1e8, 0x81e9, 0x4029, 0x01eb, 0xc02b, 0x802a, 0x41ea, 0x01ee, 0xc02e, 0x802f, 0x41ef, 0x002d, 0xc1ed, 0x81ec, 0x402c,
        0x01e4, 0xc024, 0x8025, 0x41e5, 0x0027, 0xc1e7, 0x81e6, 0x4026, 0x0022, 0xc1e2, 0x81e3, 0x4023, 0x01e1, 0xc021, 0x8020, 0x41e0,
        0x01a0, 0xc060, 0x8061, 0x41a1, 0x0063, 0xc1a3, 0x81a2, 0x4062, 0x0066, 0xc1a6, 0x81a7, 0x4067, 0x01a5, 0xc065, 0x8064, 0x41a4,
        0x006c, 0xc1ac, 0x81ad, 0x406d, 0x01af, 0xc06f, 0x806e, 0x41ae, 0x01aa, 0xc06a, 0x806b, 0x41ab, 0x0069, 0xc1a9, 0x81a8, 0x4068,
        0x0078, 0xc1b8, 0x81b9, 0x4079, 0x01bb, 0xc07b, 0x807a, 0x41ba, 0x01be, 0xc07e, 0x807f, 0x41bf, 0x007d, 0xc1bd, 0x81bc, 0x407c,
        0x01b4, 0xc074, 0x8075, 0x41b5, 0x0077, 0xc1b7, 0x81b6, 0x4076, 0x0072, 0xc1b2, 0x81b3, 0x4073, 0x01b1, 0xc071, 0x8070, 0x41b0,
        0x0050, 0xc190, 0x8191, 0x4051, 0x0193, 0xc053, 0x8052, 0x4192, 0x0196, 0xc056, 0x8057, 0x4197, 0x0055, 0xc195, 0x8194, 0x4054,
        0x019c, 0xc05c, 0x805d, 0x419d, 0x005f, 0xc19f, 0x819e, 0x405e, 0x005a, 0xc19a, 0x819b, 0x405b, 0x0199, 0xc059, 0x8058, 0x4198,
        0x0188, 0xc048, 0x8049, 0x4189, 0x004b, 0xc18b, 0x818a, 0x404a, 0x004e, 0xc18e, 0x818f, 0x404f, 0x018d, 0xc04d, 0x804c, 0x418c,
        0x0044, 0xc184, 0x8185, 0x4045, 0x0187, 0xc047, 0x8046, 0x4186, 0x0182, 0xc042, 0x8043, 0x4183, 0x0041, 0xc181, 0x8180, 0x4040
    };
    uint16_t xcrc16=seed;
    for (uint16_t t=0; t<length; t++) {
        uint16_t x=tCRC16[0xff&(xcrc16^block[t])];
        xcrc16=((xcrc16^x)>>8)|(x<<8);
    }
    return(xcrc16);
}