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Cross platform C/C++ utilities for communication.

Table of Contents

1. Getting Started
   • Installation
   • Usage
2. Documentation
   • x_crc32
   • x_rfc1071
   • x_xor
   • x_hdr
   • x_pkt
3. LICENSE

Getting Started

Installation

Put x.comm.h into your project.

Usage

x.comm.h is a single header file following the style of the stb libraries, which means users must define the macro X_COMM_H_IMPLEMENTATION in one and only one of their source files:

// in some foo.c file
#define X_COMM_H_IMPLEMENTATION
#include "x.comm.h"

// in some bar.h or bar.c file
#include "x.comm.h"

Documentation

x_crc32

Calculating the CRC32 checksum of a data array.

uint32_t x_crc32(const void* data, const size_t size, const uint32_t* prev)

Parameters

• data: The data array from which the checksum is calculated.
• size: The length of the data array when it is casted to uint8_t*.
• prev: Previous CRC32 result. Pass NULL/nullptr to this argument if no previous CRC32 result is available.

Returns

• The CRC32 checksum.

x_rfc1071

Calculating the Internet checksum (following RFC1071) of a data array.

uint16_t x_rfc1071(const void* data, const size_t size)

Parameters

• data: The data array from which the checksum is calculated.
• size: The length of the data array when it is casted to uint8_t*.

Returns

• The Internet checksum.

x_rfc1071

Calculating the XOR checksum of a data array.

uint8_t x_xor(const void* data, const size_t size)

Parameters

• data: The data array from which the checksum is calculated.
• size: The length of the data array when it is casted to uint8_t*.

Returns

• The XOR checksum.

x_hdr

Header of a packet.

typedef struct _x_hdr_
{
  uint16_t sof;  // start of frame
  uint16_t ctl;  // control code
  uint32_t opt;  // option, just use it freely
  uint64_t cnt;  // total count of packets
  uint64_t idx;  // index of current packet
  uint64_t dsz;  // size of the data chunk
  uint64_t cks;  // checksum of packet
} x_hdr;

#ifndef X_HDR_SOF
#define X_HDR_SOF (0x55AA)  // A commonly used start of frame.
#endif

#ifndef X_HDR_CNT_INF
#define X_HDR_CNT_INF UINT64_MAX  // Can be used for x_hdr::cnt.
#endif

#define X_HDR_INIT {X_HDR_SOF, 0, 0, 0, 0, 0, 0}  // Can be used to initialize x_hdr.

x_pkt

Normally the header and body of a packet can be used separately, but providing a simple encapsulation of them does no harm.

typedef struct _x_pkt_
{
  x_hdr head;
  void* body;
} x_pkt;

#define X_PKT_SOF X_HDR_SOF

#define X_PKT_CNT_INF X_HDR_CNT_INF

#define X_PKT_INIT {X_HDR_INIT, NULL}  // Can be used to initialize x_pkt.

License

Distributed under the Mulan PSL v2 license. See LICENSE for more information.