63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
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/*
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* Copyright 2021 Google LLC
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef QMath_DEFINED
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#define QMath_DEFINED
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template <int N, typename T> using V = T __attribute__((ext_vector_type(N)));
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#if !defined(__clang__)
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static_assert(false, "This only works on clang.");
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#endif
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#if defined(__SSSE3__)
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#include <immintrin.h>
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#endif
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#if defined(__ARM_NEON)
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// From section 5.5.5 of the ARM C Language Extensions (ACLE)
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#include <arm_neon.h>
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#endif
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using Q15 = V<8, uint16_t>;
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// A pure C version of the ssse3 intrinsic mm_mulhrs_epi16;
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static inline Q15 simulate_ssse3_mm_mulhrs_epi16(Q15 a, Q15 b) {
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Q15 result;
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auto m = [](int16_t r, int16_t s) {
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const int32_t rounding = 1 << 14;
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int32_t temp = (int32_t)r * (int32_t)s + rounding;
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return (int16_t)(temp >> 15);
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};
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for (int i = 0; i < 8; i++) {
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result[i] = m(a[i], b[i]);
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}
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return result;
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}
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// A pure C version of the neon intrinsic vqrdmulhq_s16;
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static inline Q15 simulate_neon_vqrdmulhq_s16(Q15 a, Q15 b) {
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Q15 result;
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const int esize = 16;
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auto m = [](int16_t r, int16_t s) {
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const int64_t rounding = 1 << (esize - 1);
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int64_t product = 2LL * (int64_t)r * (int64_t)s + rounding;
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int64_t result = product >> esize;
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// Saturate the result
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if (int64_t limit = (1LL << (esize - 1)) - 1; result > limit) { result = limit; }
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if (int64_t limit = -(1LL << (esize - 1)) ; result < limit) { result = limit; }
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return result;
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};
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for (int i = 0; i < 8; i++) {
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result[i] = m(a[i], b[i]);
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}
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return result;
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}
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#endif // QMath_DEFINED
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