TheTest & test_popcount()
{
static unsigned popcountTable[] = {0, 1, 2, 4, 5, 7, 9, 12, 13, 15, 17, 20, 22, 25, 28, 32, 33};
Data<R> dataA;
R a = dataA;
unsigned resB = (unsigned)v_reduce_sum(v_popcount(a));
EXPECT_EQ(popcountTable[R::nlanes], resB);
return *this;
}
int normHamming(const uchar* a, const uchar* b, int n)
{
CV_AVX_GUARD;
int i = 0;
int result = 0;
#if CV_AVX2
{
__m256i _r0 = _mm256_setzero_si256();
__m256i _0 = _mm256_setzero_si256();
__m256i _popcnt_table = _mm256_setr_epi8(0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4);
__m256i _popcnt_mask = _mm256_set1_epi8(0x0F);
for(; i <= n - 32; i+= 32)
{
__m256i _a0 = _mm256_loadu_si256((const __m256i*)(a + i));
__m256i _b0 = _mm256_loadu_si256((const __m256i*)(b + i));
__m256i _xor = _mm256_xor_si256(_a0, _b0);
__m256i _popc0 = _mm256_shuffle_epi8(_popcnt_table, _mm256_and_si256(_xor, _popcnt_mask));
__m256i _popc1 = _mm256_shuffle_epi8(_popcnt_table,
_mm256_and_si256(_mm256_srli_epi16(_xor, 4), _popcnt_mask));
_r0 = _mm256_add_epi32(_r0, _mm256_sad_epu8(_0, _mm256_add_epi8(_popc0, _popc1)));
}
_r0 = _mm256_add_epi32(_r0, _mm256_shuffle_epi32(_r0, 2));
result = _mm256_extract_epi32_(_mm256_add_epi32(_r0, _mm256_permute2x128_si256(_r0, _r0, 1)), 0);
}
#endif // CV_AVX2
#if CV_POPCNT
{
# if defined CV_POPCNT_U64
for(; i <= n - 8; i += 8)
{
result += (int)CV_POPCNT_U64(*(uint64*)(a + i) ^ *(uint64*)(b + i));
}
# endif
for(; i <= n - 4; i += 4)
{
result += CV_POPCNT_U32(*(uint*)(a + i) ^ *(uint*)(b + i));
}
}
#endif // CV_POPCNT
#if CV_SIMD128
{
v_uint32x4 t = v_setzero_u32();
for(; i <= n - v_uint8x16::nlanes; i += v_uint8x16::nlanes)
{
t += v_popcount(v_load(a + i) ^ v_load(b + i));
}
result += v_reduce_sum(t);
}
#endif // CV_SIMD128
#if CV_ENABLE_UNROLLED
for(; i <= n - 4; i += 4)
{
result += popCountTable[a[i] ^ b[i]] + popCountTable[a[i+1] ^ b[i+1]] +
popCountTable[a[i+2] ^ b[i+2]] + popCountTable[a[i+3] ^ b[i+3]];
}
#endif
for(; i < n; i++)
{
result += popCountTable[a[i] ^ b[i]];
}
return result;
}