文章目录
- 计算法
- 查表法
- 测试验证
crc基础相关内容可参考: https://blog.csdn.net/xiaoyuanwuhui/article/details/131259671
计算法
# 将32位数据逆序排列
def reverse32(x):x = (((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1))x = (((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2))x = (((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4))x = (((x & 0xff00ff00) >> 8) | ((x & 0x00ff00ff) << 8))return (x >> 16) | (x << 16)# 8位数据逆序排列
def reverse8(x):x = (((x & 0xaa) >> 1) | ((x & 0x55) << 1))x = (((x & 0xcc) >> 2) | ((x & 0x33) << 2))return (x >> 4) | (x << 4)# 方法一:通过标准顺序的方式求解CRC校验值
def crc32_1(data):crc = 0xFFFFFFFF # 初始值crc_polynomial = 0x04C11DB7 # 多项式值for byte in data:crc ^= (reverse8(byte) << 24) # 将输入数据逆序处理for i in range(8):if crc & 0x80000000:crc = (crc << 1) ^ crc_polynomialelse:crc = crc << 1crc = reverse32(crc) # 将结果逆序处理crc ^= 0xFFFFFFFF # 结果异或值return crc & 0xFFFFFFFF# 方法二:按照逆序的方式求解crc值
def crc32_2(data):crc = 0xFFFFFFFF # 初始值for i in data:crc = crc ^ ifor j in range(8):if crc & 0x00000001:crc = (crc >> 1) ^ 0xEDB88320 # 逆序后的多项式 0xEDB88320= reverse 0x04C11DB7else:crc = (crc >> 1)return (crc ^ 0xFFFFFFFF) & 0xFFFFFFFF # 或者写成~crc&0xffffffff 结果异或值
查表法
"""# Name: CRC-32 x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1# Poly: 0x4C11DB7# Init: 0xFFFFFFF# Refin: True# Refout: True# Xorout: 0xFFFFFFF
"""
# 逆序表
CRC32_IEEE_TABLE = [0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
]# 计算crc校验函数
def crc32_ieee(data):crc_table = CRC32_IEEE_TABLEcrc = 0xFFFFFFFF # 初始值for item in data:crc = crc_table[(crc ^ item) & 0xFF] ^ (crc >> 8)return crc ^ 0xFFFFFFFF # 结果异或值
测试验证
# 测试验证计算结果
import binasciidata1 = b'\x01\x01\x01\x01\x01\x01\x01\x01'
data2 = b'\x01'
print("binascii.crc32 = ", hex(binascii.crc32(data1)))
print("crc32_ieee() = ", hex(crc32_ieee(data1)))
print("crc_1() = ", hex(crc32_1(data1)))
print("crc_2() = ", hex(crc32_2(data1)))
输出:
binascii.crc32 = 0x2ea122d3
crc32_ieee() = 0x2ea122d3
crc_1() = 0x2ea122d3
crc_2() = 0x2ea122d3Process finished with exit code 0