license_plate_recognition/bx/BxUtils.py

import struct

# CRC16表
crc16_table = [
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
    0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
    0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
    0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
    0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
    0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
    0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
    0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
    0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
    0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
    0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
    0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
    0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
    0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
    0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
    0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
    0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
    0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
    0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
    0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
    0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
    0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
    0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
    0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
    0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
    0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
    0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
    0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
    0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
    0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
    0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
    0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040,
]


def bytes_to_uint16(src, start, little_endian=True):
    """将字节数组转换为uint16"""
    if little_endian:
        return struct.unpack_from('<H', src, start)[0]
    else:
        return struct.unpack_from('>H', src, start)[0]


def CRC16(data, offset, length):
    """计算CRC16校验（修复切片范围为offset:offset+length）"""
    crc16 = 0
    # 核心修复：切片必须是左闭右开的offset:offset+length
    for v in data[offset:length]:
        n = (v ^ crc16) & 0xFF
        crc16 >>= 8
        crc16 ^= crc16_table[n]
        crc16 &= 0xFFFF
    return crc16


def uint16_to_bin(i, little_endian=True):
    """将uint16转换为字节数组"""
    if little_endian:
        return struct.pack('<H', i)
    else:
        return struct.pack('>H', i)


class LengthError(Exception):
    """长度错误异常"""
    pass


def uint2bin(n, length, little_endian=True):
    """将无符号整数转换为指定长度的字节数组"""
    if length == 1:
        if n > 255:
            raise LengthError("需要更大的长度存储该数值")
        return bytes([n])
    elif length == 2:
        if n > 65535:
            raise LengthError("需要更大的长度存储该数值")
        if little_endian:
            return struct.pack('<H', n)
        else:
            return struct.pack('>H', n)
    elif 3 <= length <= 4:
        if n > 4294967295:
            raise LengthError("需要更大的长度存储该数值")
        if little_endian:
            return struct.pack('<I', n)
        else:
            return struct.pack('>I', n)
    elif 5 <= length <= 8:
        if n > 18446744073709551615:
            raise LengthError("需要更大的长度存储该数值")
        if little_endian:
            return struct.pack('<Q', n)
        else:
            return struct.pack('>Q', n)
    else:
        raise LengthError("非法字节长度")


def Uint2BCD(value, isHighFirst=True):
    """将无符号整数转换为BCD编码"""
    bcd = 0
    i = 0
    while value > 0:
        digit = value % 10
        bcd |= (digit << (i * 4))
        value = value // 10
        i += 1
    return bcd