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#include <stdio.h>

unsigned int LTC_pec_calc(unsigned int *data, unsigned int length);
unsigned int LTC6804_pec_lookup(data, remainder);

unsigned int LTC_pec_calc(unsigned int *data, unsigned int length)
{
    int remainder = 16; //ltc6804_pec_seed_value
    int i;
    for(i = 0; i < length; i++)
    {
        remainder = LTC6804_pec_lookup(data[i], remainder);
    }
    return (remainder * 2); 
}

unsigned int LTC6804_pec_lookup(data, remainder)
{
	unsigned int address;
	unsigned int ltc6804_pec_table[256] =
	{   0x0000, 0xc599, 0xceab, 0x0b32, 0xd8cf, 0x1d56, 0x1664, 0xd3fd, 0xf407,      0x319e, 0x3aac,
	    0xff35, 0x2cc8, 0xe951, 0xe263, 0x27fa, 0xad97, 0x680e, 0x633c, 0xa6a5, 0x7558, 0xb0c1,
	    0xbbf3, 0x7e6a, 0x5990, 0x9c09, 0x973b, 0x52a2, 0x815f, 0x44c6, 0x4ff4, 0x8a6d, 0x5b2e,
	    0x9eb7, 0x9585, 0x501c, 0x83e1, 0x4678, 0x4d4a, 0x88d3, 0xaf29, 0x6ab0, 0x6182, 0xa41b,
	    0x77e6, 0xb27f, 0xb94d, 0x7cd4, 0xf6b9, 0x3320, 0x3812, 0xfd8b, 0x2e76, 0xebef, 0xe0dd,
	    0x2544, 0x02be, 0xc727, 0xcc15, 0x098c, 0xda71, 0x1fe8, 0x14da, 0xd143, 0xf3c5, 0x365c,
	    0x3d6e, 0xf8f7, 0x2b0a, 0xee93, 0xe5a1, 0x2038, 0x07c2, 0xc25b, 0xc969, 0x0cf0, 0xdf0d,
	    0x1a94, 0x11a6, 0xd43f, 0x5e52, 0x9bcb, 0x90f9, 0x5560, 0x869d, 0x4304, 0x4836, 0x8daf,
	    0xaa55, 0x6fcc, 0x64fe, 0xa167, 0x729a, 0xb703, 0xbc31, 0x79a8, 0xa8eb, 0x6d72, 0x6640,
	    0xa3d9, 0x7024, 0xb5bd, 0xbe8f, 0x7b16, 0x5cec, 0x9975, 0x9247, 0x57de, 0x8423, 0x41ba,
	    0x4a88, 0x8f11, 0x057c, 0xc0e5, 0xcbd7, 0xe4e,  0xddb3, 0x182a, 0x1318, 0xd681, 0xf17b,
	    0x34e2, 0x3fd0, 0xfa49, 0x29b4, 0xec2d, 0xe71f, 0x2286, 0xa213, 0x678a, 0x6cb8, 0xa921,
	    0x7adc, 0xbf45, 0xb477, 0x71ee, 0x5614, 0x938d, 0x98bf, 0x5d26, 0x8edb, 0x4b42, 0x4070,
	    0x85e9, 0x0f84, 0xca1d, 0xc12f, 0x04b6, 0xd74b, 0x12d2, 0x19e0, 0xdc79, 0xfb83, 0x3e1a, 0x3528,
	    0xf0b1, 0x234c, 0xe6d5, 0xede7, 0x287e, 0xf93d, 0x3ca4, 0x3796, 0xf20f, 0x21f2, 0xe46b, 0xef59,
	    0x2ac0, 0x0d3a, 0xc8a3, 0xc391, 0x0608, 0xd5f5, 0x106c, 0x1b5e, 0xdec7, 0x54aa, 0x9133, 0x9a01,
	    0x5f98, 0x8c65, 0x49fc, 0x42ce, 0x8757, 0xa0ad, 0x6534, 0x6e06, 0xab9f, 0x7862, 0xbdfb, 0xb6c9,
	    0x7350, 0x51d6, 0x944f, 0x9f7d, 0x5ae4, 0x8919, 0x4c80, 0x47b2, 0x822b, 0xa5d1, 0x6048, 0x6b7a,
	    0xaee3, 0x7d1e, 0xb887, 0xb3b5, 0x762c, 0xfc41, 0x39d8, 0x32ea, 0xf773, 0x248e, 0xe117, 0xea25,
	    0x2fbc, 0x0846, 0xcddf, 0xc6ed, 0x0374, 0xd089, 0x1510, 0x1e22, 0xdbbb, 0x0af8, 0xcf61, 0xc453,
	    0x01ca, 0xd237, 0x17ae, 0x1c9c, 0xd905, 0xfeff, 0x3b66, 0x3054, 0xf5cd, 0x2630, 0xe3a9, 0xe89b,
	    0x2d02, 0xa76f, 0x62f6, 0x69c4, 0xac5d, 0x7fa0, 0xba39, 0xb10b, 0x7492, 0x5368, 0x96f1, 0x9dc3,
	    0x585a, 0x8ba7, 0x4e3e, 0x450c, 0x8095
	};

    address = ((remainder >> 7) ^ data) & 0xFF;    //calculate PEC table address
    remainder = (remainder << 8) ^ ltc6804_pec_table[address];      
    
    return remainder;
}

int main()
{
    printf("Hello, World!\n");
    
	unsigned int byte_CRC16[6] = {0xE5, 0xE5, 0xE5, 0xE5, 0x00, 0x00};
	
	unsigned int PEC_A = 	(LTC_pec_calc(byte_CRC16, 6) & 0xFF00) >> 8;
    
    printf("Hello, World! %s \n", PEC_A);

    return 0;
}