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Diffstat (limited to 'newlib/libm/machine/spu/headers/tanhd2.h')
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1 files changed, 173 insertions, 0 deletions
diff --git a/newlib/libm/machine/spu/headers/tanhd2.h b/newlib/libm/machine/spu/headers/tanhd2.h new file mode 100644 index 000000000..20684c818 --- /dev/null +++ b/newlib/libm/machine/spu/headers/tanhd2.h @@ -0,0 +1,173 @@ +/* -------------------------------------------------------------- */ +/* (C)Copyright 2006,2007, */ +/* International Business Machines 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. */ +/* 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 _TANHD2_H_ +#define _TANHD2_H_ 1 + +#include <spu_intrinsics.h> + +#include "expd2.h" +#include "divd2.h" + + +/* + * Taylor coefficients for tanh + */ +#define TANH_TAY01 1.000000000000000000000000000000E0 +#define TANH_TAY02 -3.333333333333333333333333333333E-1 +#define TANH_TAY03 1.333333333333333333333333333333E-1 +#define TANH_TAY04 -5.396825396825396825396825396825E-2 +#define TANH_TAY05 2.186948853615520282186948853616E-2 +#define TANH_TAY06 -8.863235529902196568863235529902E-3 +#define TANH_TAY07 3.592128036572481016925461369906E-3 +#define TANH_TAY08 -1.455834387051318268249485180702E-3 +#define TANH_TAY09 5.900274409455859813780759937000E-4 +#define TANH_TAY10 -2.391291142435524814857314588851E-4 +#define TANH_TAY11 9.691537956929450325595875000389E-5 +#define TANH_TAY12 -3.927832388331683405337080809312E-5 +#define TANH_TAY13 1.591890506932896474074427981657E-5 +#define TANH_TAY14 -6.451689215655430763190842315303E-6 +#define TANH_TAY15 2.614771151290754554263594256410E-6 +#define TANH_TAY16 -1.059726832010465435091355394125E-6 +#define TANH_TAY17 4.294911078273805854820351280397E-7 + + +/* + * FUNCTION + * vector double _tanhd2(vector double x) + * + * DESCRIPTION + * The _tanhd2 function computes the hyperbolic tangent for each + * element of the input vector. + * + * We use the following to approximate tanh: + * + * |x| <= .25: Taylor Series + * |x| > .25: tanh(x) = (exp(2x) - 1)/(exp(2x) + 1) + * + * + * SPECIAL CASES: + * - tanh(+/- 0) = +/-0 + * - tanh(+/- infinity) = +/- 1 + * - tanh(NaN) = NaN + * + */ + +static __inline vector double _tanhd2(vector double x) +{ + vector double signbit = spu_splats(-0.0); + vector double oned = spu_splats(1.0); + vector double twod = spu_splats(2.0); + vector double infd = (vector double)spu_splats(0x7FF0000000000000ull); + vector double xabs; + vector double x2; + vector unsigned long long gttaylor; + vector double e; + vector double tresult; + vector double eresult; + vector double result; + + xabs = spu_andc(x, signbit); + + /* + * This is where we switch from Taylor Series + * to exponential formula. + */ + gttaylor = spu_cmpgt(xabs, spu_splats(0.25)); + + + /* + * Taylor Series Approximation + */ + x2 = spu_mul(x,x); + tresult = spu_madd(x2, spu_splats(TANH_TAY11), spu_splats(TANH_TAY10)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY09)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY08)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY07)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY06)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY05)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY04)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY03)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY02)); + tresult = spu_madd(x2, tresult, spu_splats(TANH_TAY01)); + tresult = spu_mul(xabs, tresult); + + + /* + * Exponential Formula + * Our expd2 function gives a more accurate result in general + * with xabs instead of x for x<0. We correct for sign later. + */ + e = _expd2(spu_mul(xabs, twod)); + eresult = _divd2(spu_sub(e, oned), spu_add(e, oned)); + + + /* + * Select Taylor or exp result. + */ + result = spu_sel(tresult, eresult, gttaylor); + + /* + * Inf and NaN special cases. NaN is already in result + * for x = NaN. + */ + result = spu_sel(result, oned, spu_cmpeq(xabs, infd)); + + /* + * Antisymmetric function - preserve sign bit of x + * in the result. + */ + result = spu_sel(result, x, (vec_ullong2)signbit); + + return result; +} + +#endif /* _TANHD2_H_ */ +#endif /* __SPU__ */ |