forked from OSchip/llvm-project
57 lines
2.5 KiB
C
57 lines
2.5 KiB
C
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/*
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* Copyright (c) 2014 Advanced Micro Devices, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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// Evaluate single precisions in and cos of value in interval [-pi/4, pi/4]
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_CLC_INLINE float2
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__libclc__sincosf_piby4(float x)
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{
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// Taylor series for sin(x) is x - x^3/3! + x^5/5! - x^7/7! ...
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// = x * (1 - x^2/3! + x^4/5! - x^6/7! ...
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// = x * f(w)
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// where w = x*x and f(w) = (1 - w/3! + w^2/5! - w^3/7! ...
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// We use a minimax approximation of (f(w) - 1) / w
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// because this produces an expansion in even powers of x.
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// Taylor series for cos(x) is 1 - x^2/2! + x^4/4! - x^6/6! ...
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// = f(w)
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// where w = x*x and f(w) = (1 - w/2! + w^2/4! - w^3/6! ...
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// We use a minimax approximation of (f(w) - 1 + w/2) / (w*w)
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// because this produces an expansion in even powers of x.
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const float sc1 = -0.166666666638608441788607926e0F;
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const float sc2 = 0.833333187633086262120839299e-2F;
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const float sc3 = -0.198400874359527693921333720e-3F;
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const float sc4 = 0.272500015145584081596826911e-5F;
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const float cc1 = 0.41666666664325175238031e-1F;
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const float cc2 = -0.13888887673175665567647e-2F;
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const float cc3 = 0.24800600878112441958053e-4F;
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const float cc4 = -0.27301013343179832472841e-6F;
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float x2 = x * x;
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float2 ret;
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ret.x = mad(x*x2, mad(x2, mad(x2, mad(x2, sc4, sc3), sc2), sc1), x);
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ret.y = mad(x2*x2, mad(x2, mad(x2, mad(x2, cc4, cc3), cc2), cc1), mad(x2, -0.5f, 1.0f));
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return ret;
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}
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