forked from OctaForge/libostd
364 lines
9.4 KiB
C++
364 lines
9.4 KiB
C++
/** @defgroup Platform Platform support
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*
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* @brief Abstractions for platform (OS, toolchain) specific code.
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*
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* libostd is not only a simple utility library, it also aims to make writing
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* cross-platform code as simple as possible (while sticking to native features
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* and therefore not making your code feel foreign on the platform). This
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* module represents the base layer to achieve this.
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*
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* @{
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*/
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/** @file platform.hh
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*
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* @brief Platform specific definitions.
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*
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* This file defines various helper macros to deal with system and compiler
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* checks as well as API exports and byte order.
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*
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* @copyright See COPYING.md in the project tree for further information.
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*/
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#ifndef OSTD_PLATFORM_HH
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#define OSTD_PLATFORM_HH
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#include <cstddef>
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#include <cstdint>
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#include <type_traits>
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/* only expanded when generating documentation, define all macros */
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#ifdef OSTD_GENERATING_DOC
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/// Defined on Windows x86 and x86_64, otherwise undefined.
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#define OSTD_PLATFORM_WIN32
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/// Defined on Windows x64 only, otherwise undefined.
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#define OSTD_PLATFORM_WIN64
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/// Defined on all POSIX compliant systems, otherwise undefined.
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#define OSTD_PLATFORM_POSIX
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/// Defined on Linux.
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#define OSTD_PLATFORM_LINUX
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/// Defined on macOS.
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#define OSTD_PLATFORM_OSX
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/// Defined on DragonflyBSD.
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#define OSTD_PLATFORM_DRAGONFLYBSD
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/// Defined on FreeBSD.
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#define OSTD_PLATFORM_FREEBSD
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/// Defined on OpenBSD.
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#define OSTD_PLATFORM_OPENBSD
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/// Defined on NetBSD.
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#define OSTD_PLATFORM_NETBSD
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/// Defined on FreeBSD, NetBSD, OpenBSD and DragonflyBSD.
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#define OSTD_PLATFORM_BSD
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/// Defined on Solaris, Illumos and derivatives.
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#define OSTD_PLATFORM_SOLARIS
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/// Defined when compiling with Clang.
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#define OSTD_TOOLCHAIN_CLANG
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/// Defined when compiling with GCC or a compatible compiler such as Clang.
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#define OSTD_TOOLCHAIN_GNU
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/// Defined when compiling with Microsoft Visual Studio.
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#define OSTD_TOOLCHAIN_MSVC
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/// The value of #OSTD_BYTE_ORDER on little-endian systems.
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#define OSTD_ENDIAN_LIL
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/// The value of #OSTD_BYTE_ORDER on big-endian systems.
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#define OSTD_ENDIAN_BIG
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/// The system's byte order, either #OSTD_ENDIAN_LIL or #OSTD_ENDIAN_BIG.
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#define OSTD_BYTE_ORDER
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/** @brief Use this to annotate externally visible API.
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*
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* On Windows, this will expand differently when building a library and when
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* using the resulting API. You can define `OSTD_BUILD` to declare that you
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* are currently building the library, this is only useful for build systems
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* that build libostd itself, never for library usage. You can also define
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* `OSTD_DLL` to declare the libostd library is a dynamic one, when both
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* using and building the library. If `OSTD_DLL` is defined, then this
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* will be either `__declspec(dllexport)` or `__declspec(dllimport)`,
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* depending on whether `OSTD_BUILD` is defined, otherwise it will be
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* empty regardless of `OSTD_BUILD`.
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* On POSIX compliant systems, there are two possibilities. If your compiler
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* supports it, it can expand to `__attribute__((visibility("default")))`.
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* Otherwise, it will be empty. The `OSTD_BUILD` macro is not used then,
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* neither is `OSTD_DLL`.
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*
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* ~~~{.cc}
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* OSTD_EXPORT void foo();
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*
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* class OSTD_EXPORT bar {
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* OSTD_LOCAL void private_method(); // internal to the DSO
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*
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* public:
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* void public_method();
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* };
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*
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* OSTD_EXPORT extern baz external_variable;
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* ~~~
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*
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* @see OSTD_LOCAL
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*/
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#define OSTD_EXPORT
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/** @brief Use this to annotate APIs internal to the library.
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*
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* On Windows, this will always expand to nothing. On POSIX compliant systems,
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* it will expand to `__attribute__((visibility("hidden")))` on compliant
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* compilers, otherwise also nothing. This macro is useful typically to hide
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* private methods in classes that have been exported as whole. Otherwise,
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* APIs that are not annontated can be considered local by default (though
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* the actual visibility depends on your compiler flags).
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*/
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#define OSTD_LOCAL
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/** @brief A convenience macro for the `cdecl` calling convention on Win32.
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*
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* This will expand to nothing on all platforms except 32-bit Windows, where
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* default calling convention can be overridden. You can use this to enforce
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* the `cdecl` calling convention for external function declarations where
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* necessary without having to write Windows specific code.
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*/
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#define OSTD_CDECL
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#else /* OSTD_GENERATING_DOC */
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#if defined(WIN32) || defined(_WIN32) || (defined(__WIN32) && !defined(__CYGWIN__))
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# define OSTD_PLATFORM_WIN32 1
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# if defined(WIN64) || defined(_WIN64)
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# define OSTD_PLATFORM_WIN64 1
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# endif
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#else
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# define OSTD_PLATFORM_POSIX 1
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# if defined(__linux__)
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# define OSTD_PLATFORM_LINUX 1
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# endif
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# if defined(__APPLE__)
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# define OSTD_PLATFORM_OSX 1
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# endif
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# if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
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# define OSTD_PLATFORM_FREEBSD 1
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# define OSTD_PLATFORM_BSD 1
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# endif
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# if defined(__NetBSD__)
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# define OSTD_PLATFORM_NETBSD 1
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# define OSTD_PLATFORM_BSD 1
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# endif
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# if defined(__OpenBSD__)
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# define OSTD_PLATFORM_OPENBSD 1
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# define OSTD_PLATFORM_BSD 1
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# endif
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# if defined(__DragonFly__)
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# define OSTD_PLATFORM_DRAGONFLYBSD 1
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# define OSTD_PLATFORM_BSD 1
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# endif
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# if defined(sun) || defined(__sun)
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# define OSTD_PLATFORM_SOLARIS 1
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# endif
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#endif
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#if defined(__clang__)
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# define OSTD_TOOLCHAIN_CLANG 1
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#endif
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#if defined(__GNUC__)
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# define OSTD_TOOLCHAIN_GNU 1
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#endif
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#if defined(_MSC_VER)
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# define OSTD_TOOLCHAIN_MSVC 1
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#endif
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#define OSTD_ENDIAN_LIL 1234
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#define OSTD_ENDIAN_BIG 4321
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#ifdef OSTD_PLATFORM_LINUX
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# include <endian.h>
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# define OSTD_BYTE_ORDER __BYTE_ORDER
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#else
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# if defined(__BIG_ENDIAN__) || defined(__ARMEB__) || defined(__THUMBEB__) || \
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defined(__AARCH64EB__) || defined(__MIPSEB__) || defined(__MIPSEB) || \
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defined(_MIPSEB) || defined(__ppc__) || defined(__POWERPC__) || \
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defined(_M_PPC) || defined(__sparc__)
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# define OSTD_BYTE_ORDER OSTD_ENDIAN_BIG
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# else
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# define OSTD_BYTE_ORDER OSTD_ENDIAN_LIL
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# endif
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#endif
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#ifdef OSTD_PLATFORM_WIN32
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# ifdef OSTD_DLL
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# ifdef OSTD_BUILD
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# define OSTD_EXPORT __declspec(dllexport)
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# else
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# define OSTD_EXPORT __declspec(dllimport)
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# endif
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# else
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# define OSTD_EXPORT
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# endif
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# define OSTD_LOCAL
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#else
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# if defined(OSTD_BUILD) || defined(OSTD_DLL)
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/* -Wunused-macros */
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# endif
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# if __GNUC__ >= 4
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# define OSTD_EXPORT __attribute__((visibility("default")))
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# define OSTD_LOCAL __attribute__((visibility("hidden")))
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# else
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# define OSTD_EXPORT
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# define OSTD_LOCAL
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# endif
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#endif
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#if defined(OSTD_PLATFORM_WIN32) && !defined(OSTD_PLATFORM_WIN64)
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# define OSTD_CDECL __cdecl
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#else
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# define OSTD_CDECL
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#endif
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#endif /* OSTD_GENERATING_DOC */
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namespace ostd {
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/** @addtogroup Platform
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* @{
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*/
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#if defined(OSTD_TOOLCHAIN_GNU) && !defined(OSTD_GENERATING_DOC)
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/* using gcc/clang builtins */
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inline std::uint16_t endian_swap16(std::uint16_t x) noexcept {
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return __builtin_bswap16(x);
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}
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inline std::uint32_t endian_swap32(std::uint32_t x) noexcept {
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return __builtin_bswap32(x);
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}
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inline std::uint64_t endian_swap64(std::uint64_t x) noexcept {
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return __builtin_bswap64(x);
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}
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#elif defined(OSTD_TOOLCHAIN_MSVC) && !defined(OSTD_GENERATING_DOC)
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/* using msvc builtins */
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inline std::uint16_t endian_swap16(std::uint16_t x) noexcept {
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return _byteswap_ushort(x);
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}
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inline std::uint32_t endian_swap32(std::uint32_t x) noexcept {
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/* win64 is llp64 */
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return _byteswap_ulong(x);
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}
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inline std::uint64_t endian_swap64(std::uint64_t x) noexcept {
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return _byteswap_uint64(x);
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}
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#else
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/* fallback */
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/** @brief 16-bit byte swap. */
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inline std::uint16_t endian_swap16(std::uint16_t x) noexcept {
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return (x << 8) | (x >> 8);
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}
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/** @brief 32-bit byte swap. */
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inline std::uint32_t endian_swap32(std::uint32_t x) noexcept {
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return (x << 24) | (x >> 24) | ((x >> 8) & 0xFF00) | ((x << 8) & 0xFF0000);
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}
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/** @brief 64-bit byte swap. */
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inline std::uint64_t endian_swap64(std::uint64_t x) noexcept {
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return endian_swap32(
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std::uint32_t(x >> 32)) |
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(std::uint64_t(endian_swap32(std::uint32_t(x))) << 32
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);
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}
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#endif
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/* endian swap */
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template<
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typename T, std::size_t N = sizeof(T),
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bool IsNum = std::is_arithmetic_v<T>
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>
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struct endian_swap;
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template<typename T>
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struct endian_swap<T, 2, true> {
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T operator()(T v) const {
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union { T iv; std::uint16_t sv; } u;
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u.iv = v;
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u.sv = endian_swap16(u.sv);
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return u.iv;
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}
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};
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template<typename T>
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struct endian_swap<T, 4, true> {
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T operator()(T v) const {
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union { T iv; std::uint32_t sv; } u;
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u.iv = v;
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u.sv = endian_swap32(u.sv);
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return u.iv;
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}
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};
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template<typename T>
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struct endian_swap<T, 8, true> {
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T operator()(T v) const {
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union { T iv; std::uint64_t sv; } u;
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u.iv = v;
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u.sv = endian_swap64(u.sv);
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return u.iv;
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}
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};
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template<typename T, bool IsNum = std::is_arithmetic_v<T>>
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struct from_lil_endian;
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template<typename T>
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struct from_lil_endian<T, true> {
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T operator()(T v) const {
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if constexpr(OSTD_BYTE_ORDER == OSTD_ENDIAN_LIL) {
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return v;
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} else {
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return endian_swap<T>{}(v);
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}
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}
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};
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template<typename T, bool IsNum = std::is_arithmetic_v<T>>
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struct from_big_endian;
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template<typename T>
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struct from_big_endian<T, true> {
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T operator()(T v) const {
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if constexpr(OSTD_BYTE_ORDER != OSTD_ENDIAN_LIL) {
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return v;
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} else {
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return endian_swap<T>{}(v);
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}
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}
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};
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/** @} */
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}
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#endif
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/** @} */
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