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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [machine/] [spu/] [headers/] [expf4.h] - Rev 207
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/* -------------------------------------------------------------- */ /* (C)Copyright 2001,2008, */ /* International Business Machines Corporation, */ /* Sony Computer Entertainment, Incorporated, */ /* Toshiba Corporation, */ /* */ /* All Rights Reserved. */ /* */ /* Redistribution and use in source and binary forms, with or */ /* without modification, are permitted provided that the */ /* following conditions are met: */ /* */ /* - Redistributions of source code must retain the above copyright*/ /* notice, this list of conditions and the following disclaimer. */ /* */ /* - Redistributions in binary form must reproduce the above */ /* copyright notice, this list of conditions and the following */ /* disclaimer in the documentation and/or other materials */ /* provided with the distribution. */ /* */ /* - Neither the name of IBM Corporation nor the names of its */ /* contributors may be used to endorse or promote products */ /* derived from this software without specific prior written */ /* permission. */ /* */ /* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */ /* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */ /* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */ /* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */ /* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR */ /* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */ /* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */ /* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */ /* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */ /* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */ /* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR */ /* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */ /* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* -------------------------------------------------------------- */ /* PROLOG END TAG zYx */ #ifdef __SPU__ #ifndef _EXPF4_H_ #define _EXPF4_H_ 1 #include "floorf4.h" #include "ldexpf4.h" /* * FUNCTION * vector float _expf4(vector float x) * * DESCRIPTION * The _expf4 function computes e raised to the input x for * each of the element of the float vector. * */ static __inline vector float _expf4(vector float x) { // log2(e) vec_float4 log2e = spu_splats(1.4426950408889634074f); // Extra precision for the ln2 multiply vec_float4 ln2_hi = spu_splats(0.693359375f); vec_float4 ln2_lo = spu_splats(-2.12194440E-4f); // Coefficents for the Taylor series vec_float4 f02 = spu_splats(5.0000000000000000E-1f); // 1/2! vec_float4 f03 = spu_splats(1.6666666666666667E-1f); // 1/3! vec_float4 f04 = spu_splats(4.1666666666666667E-2f); // 1/4! vec_float4 f05 = spu_splats(8.3333333333333333E-3f); // 1/5! vec_float4 f06 = spu_splats(1.3888888888888889E-3f); // 1/6! vec_float4 f07 = spu_splats(1.9841269841269841E-4f); // 1/7! // Range reduce input, so that: // e^x = e^z * 2^n // e^x = e^z * e^(n * ln(2)) // e^x = e^(z + (n * ln(2))) vec_int4 n; // exponent of reduction vec_float4 q; // range reduced result vec_float4 z; vec_float4 r; z = spu_madd(x,log2e,spu_splats(0.5f)); z = _floorf4(z); r = spu_nmsub(z,ln2_hi,x); r = spu_nmsub(z,ln2_lo,r); n = spu_convts(z,0); z = spu_mul(r,r); // Use Horner's method on the Taylor series q = spu_madd(r,f07,f06); q = spu_madd(q,r,f05); q = spu_madd(q,r,f04); q = spu_madd(q,r,f03); q = spu_madd(q,r,f02); q = spu_madd(q,z,r); q = spu_add(q,spu_splats(1.0f)); // Adjust the result by the range reduction r = _ldexpf4( q, n ); return(r); } #endif /* _EXPF4_H_ */ #endif /* __SPU__ */