70 lines
2.6 KiB
C
70 lines
2.6 KiB
C
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#include "cbd.h"
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#include "params.h"
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#include <immintrin.h>
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#include <stdint.h>
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/*************************************************
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* Name: cbd
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*
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* Description: Given an array of uniformly random bytes, compute
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* polynomial with coefficients distributed according to
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* a centered binomial distribution with parameter KYBER_ETA
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*
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* Arguments: - poly *r: pointer to output polynomial
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* - const uint8_t *buf: pointer to input byte array
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**************************************************/
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void PQCLEAN_KYBER1024_AVX2_cbd(poly *r, const uint8_t *buf) {
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__m256i vec0, vec1, vec2, vec3, tmp;
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const __m256i mask55 = _mm256_set1_epi32(0x55555555);
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const __m256i mask33 = _mm256_set1_epi32(0x33333333);
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const __m256i mask03 = _mm256_set1_epi32(0x03030303);
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for (size_t i = 0; i < KYBER_N / 64; i++) {
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vec0 = _mm256_loadu_si256((__m256i *)&buf[32 * i]);
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vec1 = _mm256_srli_epi32(vec0, 1);
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vec0 = _mm256_and_si256(mask55, vec0);
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vec1 = _mm256_and_si256(mask55, vec1);
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vec0 = _mm256_add_epi32(vec0, vec1);
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vec1 = _mm256_srli_epi32(vec0, 2);
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vec0 = _mm256_and_si256(mask33, vec0);
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vec1 = _mm256_and_si256(mask33, vec1);
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vec2 = _mm256_srli_epi32(vec0, 4);
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vec3 = _mm256_srli_epi32(vec1, 4);
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vec0 = _mm256_and_si256(mask03, vec0);
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vec1 = _mm256_and_si256(mask03, vec1);
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vec2 = _mm256_and_si256(mask03, vec2);
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vec3 = _mm256_and_si256(mask03, vec3);
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vec1 = _mm256_sub_epi8(vec0, vec1);
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vec3 = _mm256_sub_epi8(vec2, vec3);
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vec0 = _mm256_cvtepi8_epi16(_mm256_castsi256_si128(vec1));
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vec1 = _mm256_cvtepi8_epi16(_mm256_extracti128_si256(vec1, 1));
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vec2 = _mm256_cvtepi8_epi16(_mm256_castsi256_si128(vec3));
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vec3 = _mm256_cvtepi8_epi16(_mm256_extracti128_si256(vec3, 1));
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tmp = _mm256_unpacklo_epi16(vec0, vec2);
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vec2 = _mm256_unpackhi_epi16(vec0, vec2);
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vec0 = tmp;
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tmp = _mm256_unpacklo_epi16(vec1, vec3);
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vec3 = _mm256_unpackhi_epi16(vec1, vec3);
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vec1 = tmp;
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tmp = _mm256_permute2x128_si256(vec0, vec2, 0x20);
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vec2 = _mm256_permute2x128_si256(vec0, vec2, 0x31);
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vec0 = tmp;
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tmp = _mm256_permute2x128_si256(vec1, vec3, 0x20);
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vec3 = _mm256_permute2x128_si256(vec1, vec3, 0x31);
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vec1 = tmp;
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_mm256_store_si256((__m256i *)&r->coeffs[64 * i + 0], vec0);
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_mm256_store_si256((__m256i *)&r->coeffs[64 * i + 16], vec2);
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_mm256_store_si256((__m256i *)&r->coeffs[64 * i + 32], vec1);
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_mm256_store_si256((__m256i *)&r->coeffs[64 * i + 48], vec3);
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}
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}
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