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Diffstat (limited to 'newlib/libm/machine/spu/headers/erff4.h')
| -rw-r--r-- | newlib/libm/machine/spu/headers/erff4.h | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/newlib/libm/machine/spu/headers/erff4.h b/newlib/libm/machine/spu/headers/erff4.h new file mode 100644 index 000000000..eafd9be12 --- /dev/null +++ b/newlib/libm/machine/spu/headers/erff4.h @@ -0,0 +1,132 @@ +/* -------------------------------------------------------------- */ +/* (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 _ERFF4_H_ +#define _ERFF4_H_ 1 + +#include <spu_intrinsics.h> + +#include "expf4.h" +#include "recipf4.h" +#include "divf4.h" +#include "erf_utils.h" + +/* + * FUNCTION + * vector float _erff4(vector float x) + * + * DESCRIPTION + * The erff4 function computes the error function of each element of x. + * + * C99 Special Cases: + * - erf(+0) returns +0 + * - erf(-0) returns -0 + * - erf(+infinite) returns +1 + * - erf(-infinite) returns -1 + * + */ + +static __inline vector float _erff4(vector float x) +{ + vector float onehalff = spu_splats(0.5f); + vector float zerof = spu_splats(0.0f); + vector float onef = spu_splats(1.0f); + vector float sign_mask = spu_splats(-0.0f); + + /* This is where we switch from Taylor Series to Continued Fraction approximation */ + vec_float4 approx_point = spu_splats(0.89f); + + vec_float4 xabs, xsqu, xsign; + vec_uint4 isinf; + vec_float4 tresult, presult, result; + + xsign = spu_and(x, sign_mask); + + /* Force Denorms to 0 */ + x = spu_add(x, zerof); + + xabs = spu_andc(x, sign_mask); + xsqu = spu_mul(x, x); + + /* + * Taylor Series Expansion near Zero + */ + TAYLOR_ERFF4(xabs, xsqu, tresult); + + /* + * Continued Fraction Approximation of Erfc(). + * erf = 1 - erfc + */ + CONTFRAC_ERFCF4(xabs, xsqu, presult); + presult = spu_sub(onef, presult); + + /* + * Select the appropriate approximation. + */ + result = spu_sel(tresult, presult, spu_cmpgt(xabs, approx_point)); + + /* + * Special cases/errors. + */ + + /* x = +/- infinite, return +/-1 */ + isinf = spu_cmpeq((vec_uint4)xabs, 0x7F800000); + result = spu_sel(result, onef, isinf); + + /* + * Preserve sign in result, since erf(-x) = -erf(x) + */ + result = spu_or(result, xsign); + + return result; +} + +#endif /* _ERFF4_H_ */ +#endif /* __SPU__ */ |