24 lines
870 B
C
24 lines
870 B
C
#include "sn_internal.h"
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#include "sn_intrinsic.h"
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INTERNAL __m128i facIncrement = { 4, 4, 4, 4 };
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INTERNAL __m128i facBase = { 1, 2, 3, 4 };
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INTERNAL uint64_t SN_DECL factorial_simd_sse(int n)
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{
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__m128i baseResult = facBase;
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__m128i facBaseLocal = facBase;
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const int cycle = (n - 3) >> 2;
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const uint32_t rest = (cycle << 2) + 1;
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for (size_t i = 0; i < cycle; i++) {
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facBaseLocal = _mm_add_epi32(facBaseLocal, facIncrement);
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baseResult = _mm_mullo_epi32(baseResult, facBaseLocal);
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}
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uint64_t result = (uint64_t)baseResult.m128i_i32[0] * (uint64_t)baseResult.m128i_i32[1] *
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(uint64_t)baseResult.m128i_i32[2] * (uint64_t)baseResult.m128i_i32[3];
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for (uint64_t i = rest; i < n; i++) {
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result *= i;
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}
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return result;
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}
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