LibXR::CRC32 Class Reference

32 位循环冗余校验（CRC-32）计算类 / CRC-32 checksum computation class More...

#include <crc.hpp>

Static Public Member Functions
static void	GenerateTable ()
	生成 CRC32 查找表 / Generates the CRC32 lookup table
static uint32_t	Calculate (const void *raw, size_t len)
	计算数据的 CRC32 校验码 / Computes the CRC32 checksum for the given data
static bool	Verify (const void *raw, size_t len)
	验证数据的 CRC32 校验码 / Verifies the CRC32 checksum of the given data

Static Public Attributes
static uint32_t	tab_ [256]
	CRC32 查找表 / CRC32 lookup table.
static bool	inited_
	查找表是否已初始化 / Whether the lookup table is initialized

Static Private Attributes
static const uint32_t	INIT = 0xFFFFFFFF
	CRC32 初始值 / CRC32 initial value.

Detailed Description

32 位循环冗余校验（CRC-32）计算类 / CRC-32 checksum computation class

该类实现了 CRC-32 校验算法，支持计算和验证数据的 CRC32 校验码。 This class implements the CRC-32 checksum algorithm, supporting computation and verification.

Definition at line 208 of file crc.hpp.

Constructor & Destructor Documentation

CRC32()

LibXR::CRC32::CRC32 ( )

inline

Definition at line 218 of file crc.hpp.

{}

Member Function Documentation

Calculate()

static uint32_t LibXR::CRC32::Calculate ( const void *  raw, size_t  len  )

inlinestatic

计算数据的 CRC32 校验码 / Computes the CRC32 checksum for the given data

Parameters

raw	输入数据指针 / Pointer to input data
len	数据长度 / Length of the data

Returns

计算得到的 CRC32 值 / Computed CRC32 value

Definition at line 251 of file crc.hpp.

  {
    const uint8_t *buf = reinterpret_cast<const uint8_t *>(raw);
    if (!inited_)
    {
      GenerateTable();
    }
 
    uint32_t crc = INIT;
    while (len--)
    {
      crc = tab_[(crc ^ *buf++) & 0xff] ^ (crc >> 8);
    }
    return crc;
  }

GenerateTable()

static void LibXR::CRC32::GenerateTable ( )

inlinestatic

生成 CRC32 查找表 / Generates the CRC32 lookup table

Definition at line 223 of file crc.hpp.

  {
    uint32_t crc = 0;
    for (int i = 0; i < 256; ++i)
    {
      crc = i;
      for (int j = 0; j < 8; ++j)
      {
        if (crc & 1)
        {
          crc = (crc >> 1) ^ 0xEDB88320;
        }
        else
        {
          crc >>= 1;
        }
      }
      tab_[i] = crc;
    }
    inited_ = true;
  }

Verify()

static bool LibXR::CRC32::Verify ( const void *  raw, size_t  len  )

inlinestatic

验证数据的 CRC32 校验码 / Verifies the CRC32 checksum of the given data

Parameters

raw	输入数据指针 / Pointer to input data
len	数据长度 / Length of the data

Returns

校验成功返回 true，否则返回 false / Returns true if the checksum is valid, otherwise returns false

Definition at line 274 of file crc.hpp.

  {
    const uint8_t *buf = reinterpret_cast<const uint8_t *>(raw);
    if (!inited_)
    {
      GenerateTable();
    }
 
    if (len < 2)
    {
      return false;
    }
 
    uint32_t expected = Calculate(buf, len - sizeof(uint32_t));
    return expected == (reinterpret_cast<const uint32_t *>(
                           buf + (len % 4)))[len / sizeof(uint32_t) - 1];
  }

Field Documentation

INIT

const uint32_t LibXR::CRC32::INIT = 0xFFFFFFFF

staticprivate

CRC32 初始值 / CRC32 initial value.

Definition at line 211 of file crc.hpp.

inited_

bool LibXR::CRC32::inited_

inlinestatic

Initial value:

=
      false

查找表是否已初始化 / Whether the lookup table is initialized

Definition at line 215 of file crc.hpp.

tab_

uint32_t LibXR::CRC32::tab_[256]

inlinestatic

CRC32 查找表 / CRC32 lookup table.

Definition at line 214 of file crc.hpp.

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The documentation for this class was generated from the following file:

• src/utils/crc.hpp