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| /* -------------------------------------------------------------- */ |
| /* 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__ */ |