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Diffstat (limited to 'newlib/libm/machine/spu/headers/atanhf4.h')
| -rw-r--r-- | newlib/libm/machine/spu/headers/atanhf4.h | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/newlib/libm/machine/spu/headers/atanhf4.h b/newlib/libm/machine/spu/headers/atanhf4.h new file mode 100644 index 000000000..d29ef74d4 --- /dev/null +++ b/newlib/libm/machine/spu/headers/atanhf4.h @@ -0,0 +1,149 @@ +/* -------------------------------------------------------------- */ +/* (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 _ATANHF4_H_ +#define _ATANHF4_H_ 1 + +#include <spu_intrinsics.h> +#include "logf4.h" + +/* + * FUNCTION + * vector float _atanhf4(vector float x) + * + * DESCRIPTION + * The atanhf4 function returns a vector containing the hyperbolic + * arctangents of the corresponding elements of the input vector. + * + * We are using the formula: + * atanh x = 1/2 * ln((1 + x)/(1 - x)) = 1/2 * [ln(1+x) - ln(1-x)] + * and the anti-symmetry of atanh. + * + * For x near 0, we use the Taylor series: + * atanh x = x + x^3/3 + x^5/5 + x^7/7 + x^9/9 + ... + * + * Special Cases: + * - atanh(1) = HUGE_VALF + * - atanh(-1) = -HUGE_VALF + * - The result is undefined for x outside of the domain [-1,1], + * since single-precision NaN is not supported on the SPU. + * + */ + +/* + * Maclaurin Series Coefficients + * for x near 0. + */ +#define ATANH_MAC01 1.0000000000000000000000000000000000000000000000000000000000000000000000E0 +#define ATANH_MAC03 3.3333333333333333333333333333333333333333333333333333333333333333333333E-1 +#define ATANH_MAC05 2.0000000000000000000000000000000000000000000000000000000000000000000000E-1 +#define ATANH_MAC07 1.4285714285714285714285714285714285714285714285714285714285714285714286E-1 +#if 0 +#define ATANH_MAC09 1.1111111111111111111111111111111111111111111111111111111111111111111111E-1 +#define ATANH_MAC11 9.0909090909090909090909090909090909090909090909090909090909090909090909E-2 +#define ATANH_MAC13 7.6923076923076923076923076923076923076923076923076923076923076923076923E-2 +#define ATANH_MAC15 6.6666666666666666666666666666666666666666666666666666666666666666666667E-2 +#define ATANH_MAC17 5.8823529411764705882352941176470588235294117647058823529411764705882353E-2 +#define ATANH_MAC19 5.2631578947368421052631578947368421052631578947368421052631578947368421E-2 +#define ATANH_MAC21 4.7619047619047619047619047619047619047619047619047619047619047619047619E-2 +#define ATANH_MAC23 4.3478260869565217391304347826086956521739130434782608695652173913043478E-2 +#define ATANH_MAC25 4.0000000000000000000000000000000000000000000000000000000000000000000000E-2 +#define ATANH_MAC27 3.7037037037037037037037037037037037037037037037037037037037037037037037E-2 +#define ATANH_MAC29 3.4482758620689655172413793103448275862068965517241379310344827586206897E-2 +#endif + + +static __inline vector float _atanhf4(vector float x) +{ + vec_float4 sign_mask = spu_splats(-0.0f); + vec_float4 onef = spu_splats(1.0f); + vec_float4 onehalff = spu_splats(0.5f); + vec_float4 result, fresult, mresult;; + vec_float4 xabs, xsqu; + /* Where we switch from maclaurin to formula */ + //vec_float4 switch_approx = spu_splats(0.4661f); + vec_float4 switch_approx = spu_splats(0.165f); + vec_uint4 use_form; + + xabs = spu_andc(x, sign_mask); + xsqu = spu_mul(x, x); + + /* + * Formula: + * atanh = 1/2 * ln((1 + x)/(1 - x)) = 1/2 * [ln(1+x) - ln(1-x)] + */ + fresult = spu_sub(_logf4(spu_add(onef, xabs)), _logf4(spu_sub(onef, xabs))); + fresult = spu_mul(fresult, onehalff); + + + /* + * Taylor Series + */ + mresult = spu_madd(xsqu, spu_splats((float)ATANH_MAC07), spu_splats((float)ATANH_MAC05)); + mresult = spu_madd(xsqu, mresult, spu_splats((float)ATANH_MAC03)); + mresult = spu_madd(xsqu, mresult, spu_splats((float)ATANH_MAC01)); + mresult = spu_mul(xabs, mresult); + + + /* + * Choose between series and formula + */ + use_form = spu_cmpgt(xabs, switch_approx); + result = spu_sel(mresult, fresult, use_form); + + + /* Preserve sign - atanh is anti-symmetric */ + result = spu_sel(result, x, (vec_uint4)sign_mask); + + return result; +} + +#endif /* _ATANHF4_H_ */ +#endif /* __SPU__ */ |