Function hmax

Source/astcenc_vecmathlib_avx2_8.h:487–496

* @brief Return the horizontal maximum of a vector. */

 * @brief Return the horizontal maximum of a vector.
 */
ASTCENC_SIMD_INLINE vint8 hmax(vint8 a)
{
	// Build max within groups of 2, then 4, then 8
	__m256i m = _mm256_max_epi32(a.m, _mm256_shuffle_epi32(a.m, _MM_SHUFFLE(2, 3, 0, 1)));
	m = _mm256_max_epi32(m, _mm256_shuffle_epi32(m, _MM_SHUFFLE(1, 0, 3, 2)));
	m = _mm256_max_epi32(m, _mm256_permute2x128_si256(m, m, 0x01));

	vint8 vmax(m);
	return vmax;
}

/**
 * @brief Return the horizontal maximum of a vector.