83 lines
3.2 KiB
C
83 lines
3.2 KiB
C
/* acosf4 -
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Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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All rights reserved.
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Redistribution and use in source and binary forms,
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with or without modification, are permitted provided that the
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following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of the Sony Computer Entertainment Inc nor the names
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of its contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef ___SIMD_MATH_ACOSF4_H___
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#define ___SIMD_MATH_ACOSF4_H___
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#include <simdmath.h>
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#include <altivec.h>
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#include <simdmath/sqrtf4.h>
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//
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// Computes the inverse cosine of all four slots of x.
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//
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static inline vector float
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_acosf4 (vector float x)
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{
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vector float result, xabs;
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vector float t1;
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vector float xabs2, xabs4;
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vector float hi, lo;
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vector float neg, pos;
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vector unsigned int select;
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xabs = vec_abs(x);
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select = (vector unsigned int)(vec_sra((vector signed int)(x), __vec_splatsu4(31)));
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t1 = _sqrtf4(vec_sub(__vec_splatsf4(1.0f), xabs));
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/* Instruction counts can be reduced if the polynomial was
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* computed entirely from nested (dependent) fma's. However,
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* to reduce the number of pipeline stalls, the polygon is evaluated
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* in two halves (hi amd lo).
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*/
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xabs2 = vec_madd(xabs, xabs, __vec_splatsf4(0.0f) );
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xabs4 = vec_madd(xabs2, xabs2, __vec_splatsf4(0.0f) );
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hi = vec_madd(__vec_splatsf4(-0.0012624911) , xabs, __vec_splatsf4(0.0066700901));
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hi = vec_madd(hi, xabs, __vec_splatsf4(-0.0170881256));
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hi = vec_madd(hi, xabs, __vec_splatsf4( 0.0308918810));
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lo = vec_madd(__vec_splatsf4(-0.0501743046), xabs, __vec_splatsf4(0.0889789874));
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lo = vec_madd(lo, xabs, __vec_splatsf4(-0.2145988016));
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lo = vec_madd(lo, xabs, __vec_splatsf4( 1.5707963050));
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result = vec_madd(hi, xabs4, lo);
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/* Adjust the result if x is negactive.
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*/
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neg = vec_nmsub(t1, result, __vec_splatsf4(3.1415926535898f));
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pos = vec_madd(t1, result, __vec_splatsf4(0.0f));
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result = vec_sel(pos, neg, select);
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return result;
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}
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#endif
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