1*89a51591SEric Biggers // SPDX-License-Identifier: GPL-2.0-only 2*89a51591SEric Biggers /* 3*89a51591SEric Biggers * crc16.c 4*89a51591SEric Biggers */ 5*89a51591SEric Biggers 6*89a51591SEric Biggers #include <linux/types.h> 7*89a51591SEric Biggers #include <linux/module.h> 8*89a51591SEric Biggers #include <linux/crc16.h> 9*89a51591SEric Biggers 10*89a51591SEric Biggers /** CRC table for the CRC-16. The poly is 0x8005 (x^16 + x^15 + x^2 + 1) */ 11*89a51591SEric Biggers static const u16 crc16_table[256] = { 12*89a51591SEric Biggers 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 13*89a51591SEric Biggers 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440, 14*89a51591SEric Biggers 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 15*89a51591SEric Biggers 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841, 16*89a51591SEric Biggers 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, 17*89a51591SEric Biggers 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41, 18*89a51591SEric Biggers 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, 19*89a51591SEric Biggers 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040, 20*89a51591SEric Biggers 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, 21*89a51591SEric Biggers 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, 22*89a51591SEric Biggers 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, 23*89a51591SEric Biggers 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, 24*89a51591SEric Biggers 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, 25*89a51591SEric Biggers 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, 26*89a51591SEric Biggers 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, 27*89a51591SEric Biggers 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, 28*89a51591SEric Biggers 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, 29*89a51591SEric Biggers 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441, 30*89a51591SEric Biggers 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, 31*89a51591SEric Biggers 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, 32*89a51591SEric Biggers 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, 33*89a51591SEric Biggers 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, 34*89a51591SEric Biggers 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, 35*89a51591SEric Biggers 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, 36*89a51591SEric Biggers 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, 37*89a51591SEric Biggers 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, 38*89a51591SEric Biggers 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, 39*89a51591SEric Biggers 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, 40*89a51591SEric Biggers 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, 41*89a51591SEric Biggers 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, 42*89a51591SEric Biggers 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, 43*89a51591SEric Biggers 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040 44*89a51591SEric Biggers }; 45*89a51591SEric Biggers 46*89a51591SEric Biggers /** 47*89a51591SEric Biggers * crc16 - compute the CRC-16 for the data buffer 48*89a51591SEric Biggers * @crc: previous CRC value 49*89a51591SEric Biggers * @p: data pointer 50*89a51591SEric Biggers * @len: number of bytes in the buffer 51*89a51591SEric Biggers * 52*89a51591SEric Biggers * Returns the updated CRC value. 53*89a51591SEric Biggers */ 54*89a51591SEric Biggers u16 crc16(u16 crc, const u8 *p, size_t len) 55*89a51591SEric Biggers { 56*89a51591SEric Biggers while (len--) 57*89a51591SEric Biggers crc = (crc >> 8) ^ crc16_table[(crc & 0xff) ^ *p++]; 58*89a51591SEric Biggers return crc; 59*89a51591SEric Biggers } 60*89a51591SEric Biggers EXPORT_SYMBOL(crc16); 61*89a51591SEric Biggers 62*89a51591SEric Biggers MODULE_DESCRIPTION("CRC16 calculations"); 63*89a51591SEric Biggers MODULE_LICENSE("GPL"); 64*89a51591SEric Biggers 65