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Move packing 16x16b -> 16x2b into separate function

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This commit is contained in:
Pauli Oikkonen 2018-12-20 10:51:44 +02:00
parent 3b635309a1
commit 016eb014ad
1 changed files with 23 additions and 14 deletions
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37
src/strategies/avx2/encode_coding_tree-avx2.c
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@ -48,6 +48,28 @@ static INLINE uint32_t _mm32_cmpgt_epu2(uint32_t a, uint32_t b)
return res;
}
static INLINE uint32_t pack_16x16b_to_16x2b(__m256i src)
{
/*
* For each 16-bit element in src:
* Clip it to max. 3 (assuming the numbers to be unsigned)
* Shift
* 0000 0000 0000 00XY Clip to [0, 3]
* 0000 000X Y000 0000 Shift word to align LSBs across byte boundary
* 0000 0001 1000 0000 cmpmask to be compared against
* XXXX XXXX YYYY YYYY Comparison result, for movemask
*/
const __m256i threes = _mm256_set1_epi16(3);
const __m256i cmpmask = _mm256_set1_epi16(0x0180);
__m256i clipped = _mm256_min_epu16 (src, threes);
__m256i shifted = _mm256_slli_epi16 (clipped, 7);
__m256i cmpres = _mm256_cmpeq_epi8 (shifted, cmpmask);
uint32_t result = _mm256_movemask_epi8(cmpres);
return result;
}
/**
* \brief Context derivation process of coeff_abs_significant_flag,
* parallelized to handle 16 coeffs at once
@ -572,25 +594,12 @@ void kvz_encode_coeff_nxn_avx2(encoder_state_t * const state,
if (c1 == 0 || num_non_zero > C1FLAG_NUMBER) {
const __m256i ones = _mm256_set1_epi16(1);
const __m256i threes = _mm256_set1_epi16(3);
__m256i abs_coeffs_gt1 = _mm256_cmpgt_epi16 (abs_coeffs, ones);
uint32_t acgt1_bits = _mm256_movemask_epi8(abs_coeffs_gt1);
uint32_t first_acgt1_bpos = _tzcnt_u32(acgt1_bits);
/*
* Extract low two bits (X and Y) from each coeff clipped at 3:
* abs_coeffs_max3: 0000 0000 0000 00XY
* abs_coeffs_tmp1: 0000 000X Y000 0000
* abs_coeffs_tmp2: XXXX XXXX YYYY YYYY inverted
*
* abs_coeffs can be clipped to [0, 3] for this because it will only
* be compared whether it's >= X, where X is between 0 and 3
*/
__m256i abs_coeffs_max3 = _mm256_min_epu16 (abs_coeffs, threes);
__m256i abs_coeffs_tmp1 = _mm256_slli_epi16 (abs_coeffs_max3, 7);
__m256i abs_coeffs_tmp2 = _mm256_cmpeq_epi8 (abs_coeffs_tmp1, zero);
uint32_t abs_coeffs_base4 = ~(_mm256_movemask_epi8(abs_coeffs_tmp2));
uint32_t abs_coeffs_base4 = pack_16x16b_to_16x2b(abs_coeffs);
const uint32_t ones_base4 = 0x55555555;
const uint32_t twos_base4 = 0xaaaaaaaa;