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‎.gitignore

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*~
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*#
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*.bak

‎README.md

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# Portable Snippets
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This is a collection of snippets written in C for doing various tasks
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in a relatively portable manner. Some of them may be a bit overkill
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for your application; feel free to just take what you need.
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Everything is CC0 licensed (public domain).
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This repository currently contains:
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* endian.h — endianness detection and swapping
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Please don't be shy about filing issues about these; if you have
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problems it's likely others will, as well, so we would like to fix
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them.
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If you have a snippet you would like to contribute, please file an
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issue or pull request. These are coming soon (I have the code, just
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need to clean it up and/or remove some proprietary bits):
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* Runtime CPU feature detection (SSE, AVX, NEON, etc.).
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* High-precision time. There is
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[some code in µnit for this](https://github.com/nemequ/munit/blob/ca64cf27eda984855323917736ed595030f150db/munit.c#L274)
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but it's geared towards timing.
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* A portable stdatomic.h
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Some things don't really fit in a "snippet", or aren't public domain
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and so cannot be included in this repository, so here are a few
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projects for doing things portably which you may be interested in:
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* [parg](https://github.com/jibsen/parg) —
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Argument parsing similar to getopt/getopt_long. Public domain.
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* [TinyCThread](https://tinycthread.github.io/) — Implements the C11
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threads API on top of pthreads and the Windows API. zlib license.
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* [pstdint.h](http://www.azillionmonkeys.com/qed/pstdint.h) —
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stdint.h/cstdint for platforms which don't have it. 3-clause BSD
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license.
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* [safe-math](https://github.com/nemequ/safe-math) — portable
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overflow-safe path functions. MIT license.
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If there is a project you'd like to see added to the list, please file
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an issue.

‎endian.h

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/* Portable Snippets - https://gitub.com/nemequ/portable-snippets
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* Created by Evan Nemerson <[email protected]>
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*
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* To the extent possible under law, the authors have waived all
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* copyright and related or neighboring rights to Hedley. For
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* details, see the Creative Commons Zero 1.0 Universal license at
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* https://creativecommons.org/publicdomain/zero/1.0/
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******************************************************************
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* Endianness detection and swapping
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* v1
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*
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* This is probably a bit overkill; you may want to simplify things a
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* bit (i.e., remove unused macros) if you copy this into your
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* project.
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*
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* Support for PDP endian is incomplete.
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*
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* If you improve this, *please* contribute your change back to us.
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*/
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/* TODO: don't require this on old versions of MSVC */
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#include <stdint.h>
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#if !defined(PSNIP_ENDIAN_H)
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#define PSNIP_ENDIAN_H
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#if !defined(PSNIP_LITTLE_ENDIAN)
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# define PSNIP_LITTLE_ENDIAN 1234
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#endif
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#if !defined(PSNIP_BIG_ENDIAN)
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# define PSNIP_BIG_ENDIAN 4321
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#endif
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#if !defined(PSNIP_PDP_ENDIAN)
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# define PSNIP_PDP_ENDIAN 3412
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#endif
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/* Detection
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*
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* Detecting endianness can be a bit tricky. There isn't really a
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* good standard way of determining endianness, and it's actually
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* possible to mix endianness within a single program. This is
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* currently pretty rare, though.
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*
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* We define PSNIP_BYTE_ORDER to PSNIP_LITTLE_ENDIAN,
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* PSNIP_BIG_ENDIAN, or PSNIP_PDP_ENDIAN. Additionally, you can use
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* the PSNIP_RT_BYTE_ORDER to check the runtime byte order, which is a
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* bit more reliable (though it does introduce some runtime overhead.
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*
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* In the event we are unable to determine endianness at compile-time,
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* PSNIP_BYTE_ORDER is left undefined and you will be forced to rely
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* on PSNIP_RT_BYTE_ORDER. */
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#if !defined(PSNIP_BYTE_ORDER)
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/* GCC (and compilers masquerading as GCC) define __BYTE_ORDER__. */
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# if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(__BYTE_ORDER__) && defined(__ORDER_PDP_ENDIAN__) && (__BYTE_ORDER__ == __ORDER_PDP_ENDIAN__)
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# define PSNIP_BYTE_ORDER PSNIP_PDP_ENDIAN
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/* We know the endianness of some common architectures. Common
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* architectures not listed (ARM, POWER, MIPS, etc.) here are
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* bi-endian. */
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# elif defined(__amd64) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(__s390x__) || defined(__zarch__)
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# define PSNIP_BYTE_ORDER PSNIP_BIG_ENDIAN
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/* Looks like we'll have to rely on the platform. If we're missing a
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* platform, please let us know. */
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# elif defined(_WIN32)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(sun) || defined(__sun) /* Solaris */
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# include <sys/byteorder.h>
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# if defined(_LITTLE_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(_BIG_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_BIG_ENDIAN
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# endif
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# elif defined(__APPLE__)
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# include <libkern/OSByteOrder.h>
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# if defined(__LITTLE_ENDIAN__)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(__BIG_ENDIAN__)
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# define PSNIP_BYTE_ORDER PSNIP_BIG_ENDIAN
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# endif
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# elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__bsdi__) || defined(__DragonFly__) || defined(BSD)
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# include <machine/endian.h>
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# if defined(__BYTE_ORDER) && (__BYTE_ORDER == __LITTLE_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_BIG_ENDIAN
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# elif defined(__BYTE_ORDER) && (__BYTE_ORDER == __PDP_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_PDP_ENDIAN
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# endif
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# else
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# include <endian.h>
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# if defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && (__BYTE_ORDER == __LITTLE_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_LITTLE_ENDIAN
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# elif defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && (__BYTE_ORDER == __BIG_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_BIG_ENDIAN
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# elif defined(__BYTE_ORDER) && defined(__PDP_ENDIAN) && (__BYTE_ORDER == __PDP_ENDIAN)
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# define PSNIP_BYTE_ORDER PSNIP_PDP_ENDIAN
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# endif
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# endif
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#endif
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/* PDP endian not yet supported. Patches welcome. */
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#if defined(PSNIP_BYTE_ORDER) && (PSNIP_BYTE_ORDER == PSNIP_PDP_ENDIAN)
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# undef PSNIP_PDP_ENDIAN
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#endif
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/* We need fixed-length types for some stuff. */
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#if defined(_WIN32)
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# define PSNIP_ENDIAN_UINT16_T unsigned short
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# define PSNIP_ENDIAN_UINT32_T unsigned long
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# define PSNIP_ENDIAN_UINT64_T unsigned __int64
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#else
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# include <stdint.h>
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# define PSNIP_ENDIAN_UINT16_T uint16_t
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# define PSNIP_ENDIAN_UINT32_T uint32_t
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# define PSNIP_ENDIAN_UINT64_T uint64_t
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#endif
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/* Runtime detection. */
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#define PSNIP_RT_BYTE_ORDER_IS_LE \
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((((union { unsigned char bytes[4]; PSNIP_ENDIAN_UINT32_T value; }) { { 1, 2, 3, 4 } }).value) == UINT32_C(0x04030201))
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#define PSNIP_RT_BYTE_ORDER_IS_BE \
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((((union { unsigned char bytes[4]; PSNIP_ENDIAN_UINT32_T value; }) { { 1, 2, 3, 4 } }).value) == UINT32_C(0x01020304))
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#define PSNIP_RT_BYTE_ORDER \
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(PSNIP_RT_BYTE_ORDER_IS_LE ? PSNIP_LITTLE_ENDIAN : (PSNIP_RT_BYTE_ORDER_IS_BE ? PSNIP_BIG_ENDIAN : PSNIP_PDP_ENDIAN))
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/* Swapping
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*
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* We define PSNIP_BSWAP16, PSNIP_BSWAP32, and PSNIP_BSWAP64 to
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* unconditionally swap byte orders between big-endian and
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* little-endian.
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*
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* We also define macros for reading and writing values with different
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* endiannesses which will be preprocessed to either a swap operation
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* or identity, depending on the system's endianness as determined at
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* compile time or, if none could be determined, we fall back on
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* runtime detection. These are probably the macros you want to use.
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* They are:
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*
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* PSNIP_READ_LE16, PSNIP_READ_LE32, PSNIP_READ_LE64,
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* PSNIP_READ_BE16, PSNIP_READ_BE32, PSNIP_READ_BE64,
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* PSNIP_WRITE_LE16, PSNIP_WRITE_LE32, PSNIP_WRITE_LE64,
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* PSNIP_WRITE_BE16, PSNIP_WRITE_BE32, PSNIP_WRITE_BE64,
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*
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* Finally, there are runtime-only version of those macros which
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* ignore the compile-time endianness and always check at runtime:
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*
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* PSNIP_READ_RT_LE16, PSNIP_READ_RT_LE32, PSNIP_READ_RT_LE64,
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* PSNIP_READ_RT_BE16, PSNIP_READ_RT_BE32, PSNIP_READ_RT_BE64,
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* PSNIP_WRITE_RT_LE16, PSNIP_WRITE_RT_LE32, PSNIP_WRITE_RT_LE64,
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* PSNIP_WRITE_RT_BE16, PSNIP_WRITE_RT_BE32, PSNIP_WRITE_RT_BE64
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*
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* Interestingly, GCC and clang will detect that these are for
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* swapping endianness and optimize them into an unconditional bswap,
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* at least when endianness is known at compile time. Intel, OTOH,
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* keeps the runtime checks.
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*/
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#if defined(__clang__) && defined(__has_builtin)
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# if !defined(PSNIP_BSWAP16) && __has_builtin(__builtin_bswap16)
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# define PSNIP_BSWAP16(v) __builtin_bswap16((int16_t) (v))
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# endif
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# if !defined(PSNIP_BSWAP32) && __has_builtin(__builtin_bswap32)
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# define PSNIP_BSWAP32(v) __builtin_bswap32((int32_t) (v))
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# endif
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# if !defined(PSNIP_BSWAP64) && __has_builtin(__builtin_bswap64)
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# define PSNIP_BSWAP64(v) __builtin_bswap64((int64_t) (v))
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# endif
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#endif
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#if defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
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# if !defined(PSNIP_BSWAP16) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))
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# define PSNIP_BSWAP16(v) __builtin_bswap16((int16_t) (v))
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# endif
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# if !defined(PSNIP_BSWAP32)
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# define PSNIP_BSWAP32(v) __builtin_bswap32((int32_t) (v))
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# endif
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# if !defined(PSNIP_BSWAP64)
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# define PSNIP_BSWAP64(v) __builtin_bswap64((int64_t) (v))
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# endif
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#endif
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#if defined(_MSC_VER) && _MSC_VER >= 1310
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# include <stdlib.h>
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# if !defined(PSNIP_BSWAP16)
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# define PSNIP_BSWAP16(v) _byteswap_ushort((unsigned short) (v))
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# endif
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# if !defined(PSNIP_BSWAP16)
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# define PSNIP_BSWAP32(v) _byteswap_ulong((unsigned long) (v))
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# endif
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# if !defined(PSNIP_BSWAP16)
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# define PSNIP_BSWAP64(v) _byteswap_uint64((unsigned __int64) (v))
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# endif
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#endif
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#if !defined(PSNIP_BSWAP16)
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# define PSNIP_BSWAP16(v) \
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(((((PSNIP_ENDIAN_UINT16_T) (v)) & UINT16_C(0xff00)) >> 8) | \
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((((PSNIP_ENDIAN_UINT16_T) (v)) & UINT16_C(0x00ff)) << 8))
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#endif
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#if !defined(PSNIP_BSWAP32)
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# define PSNIP_BSWAP32(v) \
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(((((PSNIP_ENDIAN_UINT32_T) (v)) & UINT32_C(0xff000000)) >> 24) | \
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((((PSNIP_ENDIAN_UINT32_T) (v)) & UINT32_C(0x00ff0000)) >> 8) | \
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((((PSNIP_ENDIAN_UINT32_T) (v)) & UINT32_C(0x0000ff00)) << 8) | \
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((((PSNIP_ENDIAN_UINT32_T) (v)) & UINT32_C(0x000000ff)) << 24))
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#endif
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#if !defined(PSNIP_BSWAP64)
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# define PSNIP_BSWAP64(v) \
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(((((PSNIP_ENDIAN_UINT64_T) (v)) & (0xff00000000000000ULL)) >> 56) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x00ff000000000000ULL)) >> 40) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x0000ff0000000000ULL)) >> 24) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x000000ff00000000ULL)) >> 8) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x00000000ff000000ULL)) << 8) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x0000000000ff0000ULL)) << 24) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x000000000000ff00ULL)) << 40) | \
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((((PSNIP_ENDIAN_UINT64_T) (v)) & (0x00000000000000ffULL)) << 56));
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#endif
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static inline PSNIP_ENDIAN_UINT16_T psnip_io_le16(PSNIP_ENDIAN_UINT16_T v) { return (PSNIP_RT_BYTE_ORDER == PSNIP_LITTLE_ENDIAN ? (v) : PSNIP_BSWAP16(v)); }
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static inline PSNIP_ENDIAN_UINT32_T psnip_io_le32(PSNIP_ENDIAN_UINT32_T v) { return (PSNIP_RT_BYTE_ORDER == PSNIP_LITTLE_ENDIAN ? (v) : PSNIP_BSWAP32(v)); }
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static inline PSNIP_ENDIAN_UINT64_T psnip_io_le64(PSNIP_ENDIAN_UINT64_T v) { return (PSNIP_RT_BYTE_ORDER == PSNIP_LITTLE_ENDIAN ? (v) : PSNIP_BSWAP64(v)); }
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static inline PSNIP_ENDIAN_UINT16_T psnip_io_be16(PSNIP_ENDIAN_UINT16_T v) { return (PSNIP_RT_BYTE_ORDER == PSNIP_BIG_ENDIAN ? (v) : PSNIP_BSWAP16(v)); }
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static inline PSNIP_ENDIAN_UINT32_T psnip_io_be32(PSNIP_ENDIAN_UINT32_T v) { return (PSNIP_RT_BYTE_ORDER == PSNIP_BIG_ENDIAN ? (v) : PSNIP_BSWAP32(v)); }
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static inline PSNIP_ENDIAN_UINT64_T psnip_io_be64(PSNIP_ENDIAN_UINT64_T v) { return (PSNIP_RT_BYTE_ORDER == PSNIP_BIG_ENDIAN ? (v) : PSNIP_BSWAP64(v)); }
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#define PSNIP_READ_RT_LE16(v) psnip_io_le16(v)
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#define PSNIP_READ_RT_LE32(v) psnip_io_le32(v)
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#define PSNIP_READ_RT_LE64(v) psnip_io_le64(v)
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#define PSNIP_READ_RT_BE16(v) psnip_io_be16(v)
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#define PSNIP_READ_RT_BE32(v) psnip_io_be32(v)
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#define PSNIP_READ_RT_BE64(v) psnip_io_be64(v)
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#if defined(PSNIP_BYTE_ORDER)
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# if PSNIP_BYTE_ORDER == PSNIP_LITTLE_ENDIAN
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# define PSNIP_READ_LE16(v) (v)
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# define PSNIP_READ_LE32(v) (v)
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# define PSNIP_READ_LE64(v) (v)
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# define PSNIP_READ_BE16(v) PSNIP_BSWAP16(v)
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# define PSNIP_READ_BE32(v) PSNIP_BSWAP32(v)
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# define PSNIP_READ_BE64(v) PSNIP_BSWAP64(v)
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# elif PSNIP_BYTE_ORDER == PSNIP_BIG_ENDIAN
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# define PSNIP_READ_LE16(v) PSNIP_BSWAP16(v)
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# define PSNIP_READ_LE32(v) PSNIP_BSWAP32(v)
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# define PSNIP_READ_LE64(v) PSNIP_BSWAP64(v)
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# define PSNIP_READ_BE16(v) (v)
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# define PSNIP_READ_BE32(v) (v)
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# define PSNIP_READ_BE64(v) (v)
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# endif
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#else
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# define PSNIP_READ_LE16(v) PSNIP_READ_RT_LE16(v)
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# define PSNIP_READ_LE32(v) PSNIP_READ_RT_LE32(v)
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# define PSNIP_READ_LE64(v) PSNIP_READ_RT_LE64(v)
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# define PSNIP_READ_BE16(v) PSNIP_READ_RT_BE16(v)
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# define PSNIP_READ_BE32(v) PSNIP_READ_RT_BE32(v)
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# define PSNIP_READ_BE64(v) PSNIP_READ_RT_BE64(v)
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#endif
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#define PSNIP_WRITE_LE16(v) PSNIP_READ_LE16(v)
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#define PSNIP_WRITE_LE32(v) PSNIP_READ_LE32(v)
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#define PSNIP_WRITE_LE64(v) PSNIP_READ_LE64(v)
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#define PSNIP_WRITE_BE16(v) PSNIP_READ_BE16(v)
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#define PSNIP_WRITE_BE32(v) PSNIP_READ_BE32(v)
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#define PSNIP_WRITE_BE64(v) PSNIP_READ_BE64(v)
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#define PSNIP_WRITE_RT_LE16(v) PSNIP_READ_RT_LE16(v)
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#define PSNIP_WRITE_RT_LE32(v) PSNIP_READ_RT_LE32(v)
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#define PSNIP_WRITE_RT_LE64(v) PSNIP_READ_RT_LE64(v)
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#define PSNIP_WRITE_RT_BE16(v) PSNIP_READ_RT_BE16(v)
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#define PSNIP_WRITE_RT_BE32(v) PSNIP_READ_RT_BE32(v)
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#define PSNIP_WRITE_RT_BE64(v) PSNIP_READ_RT_BE64(v)
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#endif /* !defined(PSNIP_ENDIAN_H) */

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