Macros
#define	XXH_DISPATCH_SCALAR 1
	Enables/dispatching the scalar code path.

#define	XXH_DISPATCH_AVX2 0
	Enables/disables dispatching for AVX2.

#define	XXH_DISPATCH_AVX512 0
	Enables/disables dispatching for AVX512.

#define	XXH_TARGET_SSE2 /* disable attribute target */
	Allows a function to be compiled with SSE2 intrinsics.

#define	XXH_TARGET_AVX2 /* disable attribute target */
	Like XXH_TARGET_SSE2, but for AVX2.

#define	XXH_TARGET_AVX512 /* disable attribute target */
	Like XXH_TARGET_SSE2, but for AVX512.

Detailed Description

Macro Definition Documentation

#define XXH_DISPATCH_SCALAR 1

Enables/dispatching the scalar code path.

If this is defined to 0, SSE2 support is assumed. This reduces code size when the scalar path is not needed.

This is automatically defined to 0 when...

#define XXH_DISPATCH_AVX2 0

Enables/disables dispatching for AVX2.

This is automatically detected if it is not defined.

GCC 4.7 and later are known to support AVX2, but >4.9 is required for to get the AVX2 intrinsics and typedefs without -mavx -mavx2.
Visual Studio 2013 Update 2 and later are known to support AVX2.
The GCC/Clang internal header <avx2intrin.h> is detected. While this is not allowed to be included directly, it still appears in the builtin include path and is detectable with __has_include.

#define XXH_DISPATCH_AVX512 0

Enables/disables dispatching for AVX512.

Automatically detected if one of the following conditions is met:

GCC 4.9 and later are known to support AVX512.
Visual Studio 2017 and later are known to support AVX2.
The GCC/Clang internal header <avx512fintrin.h> is detected. While this is not allowed to be included directly, it still appears in the builtin include path and is detectable with __has_include.

#define XXH_TARGET_SSE2 /* disable attribute target */

Allows a function to be compiled with SSE2 intrinsics.

Uses __attribute__((__target__("sse2"))) on GCC to allow SSE2 to be used even with -mno-sse2.