https://github.com/zhuagenborn/cpp-struct-byte-order-converter

⚒ A script used to generate byte reversing functions for a C/C++ structure.
https://github.com/zhuagenborn/cpp-struct-byte-order-converter

big-endian byte-order endianness little-endian

Last synced: 11 days ago
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⚒ A script used to generate byte reversing functions for a C/C++ structure.

• Host: GitHub
• URL: https://github.com/zhuagenborn/cpp-struct-byte-order-converter
• Owner: Zhuagenborn
• License: mit
• Created: 2024-07-31T08:55:39.000Z (4 months ago)
• Default Branch: main
• Last Pushed: 2024-08-26T02:53:15.000Z (3 months ago)
• Last Synced: 2024-08-26T03:58:14.705Z (3 months ago)
• Topics: big-endian, byte-order, endianness, little-endian
• Language: PowerShell
• Homepage:
• Size: 7.81 KB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE
  • Citation: CITATION.cff

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README

        
# *C/C++* Structure Byte Order Converter

![PowerShell](badges/PowerShell.svg)

![GitHub Actions](badges/Made-with-GitHub-Actions.svg)

![License](badges/License-MIT.svg)

## Introduction

This script can read a *C/C++* structure definition from the clipboard and generate byte reversing functions for the structure with `ntoh` or `hton` APIs.

## Usage

Suppose we have a structure `Foo`:

```c++

struct Foo {

    unsigned short us;

    int i8 : 8;

    int i24 : 24;

    signed long sl[4];

    char c[12];

    long long ll24 : 24;

    signed int si8 : 8;

    short s;

};

```

Copy the structure definition to the clipboard and run the script. We can get two reversing functions:

```c++

void ReverseFooToLittleEndian(Foo *const data) {

    data->us = ntohs(data->us);

    *(int*)((unsigned char*)(&data->us) + sizeof(data->us) + 0) = ntohl(*(int*)((unsigned char*)(&data->us) + sizeof(data->us) + 0));

    for (size_t i = 0; i < sizeof(data->sl) / sizeof(data->sl[0]); i++) {

        data->sl[i] = ntohl(data->sl[i]);

    }

    *(long long*)((unsigned char*)(&data->c) + sizeof(data->c) + 0) = ntohll(*(long long*)((unsigned char*)(&data->c) + sizeof(data->c) + 0));

    *(signed int*)((unsigned char*)(&data->c) + sizeof(data->c) + 8) = ntohl(*(signed int*)((unsigned char*)(&data->c) + sizeof(data->c) + 8));

    data->s = ntohs(data->s);

}

void ReverseFooToBigEndian(Foo *const data) {

    data->us = htons(data->us);

    *(int*)((unsigned char*)(&data->us) + sizeof(data->us) + 0) = htonl(*(int*)((unsigned char*)(&data->us) + sizeof(data->us) + 0));

    for (size_t i = 0; i < sizeof(data->sl) / sizeof(data->sl[0]); i++) {

        data->sl[i] = htonl(data->sl[i]);

    }

    *(long long*)((unsigned char*)(&data->c) + sizeof(data->c) + 0) = htonll(*(long long*)((unsigned char*)(&data->c) + sizeof(data->c) + 0));

    *(signed int*)((unsigned char*)(&data->c) + sizeof(data->c) + 8) = htonl(*(signed int*)((unsigned char*)(&data->c) + sizeof(data->c) + 8));

    data->s = htons(data->s);

}

```

The output can be copied directly to the clipboard:

```console

PS> .\Build-ByteReverseFunctions.ps1 | Set-Clipboard

```

### Warnings

- The structure name can only be extracted from the `struct` statement.

- The script can only detect single-line comments (`//`).

- The following settings may differ from the script on some systems and compilers.

  - Endianness.

  - The sizes of fundamental *C/C++* types.

  - The order of bit-fields.

  - Field alignment.

## License

Distributed under the *MIT License*. See `LICENSE` for more information.