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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [machine/] [spu/] [headers/] [sqrtf4.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 _SQRTF4_H_ #define _SQRTF4_H_ 1 #include <spu_intrinsics.h> /* * FUNCTION * vector float _sqrtf4(vector float in) * * DESCRIPTION * The _sqrtf4 function computes the square root of the vector input "in" *and returns the result. * */ static __inline vector float _sqrtf4(vector float in) { vec_uint4 exp, valid; vec_uint4 mask = spu_splats((unsigned int)0xFF000000); vec_uint4 half = spu_splats((unsigned int)0x00800000); vec_float4 one = spu_splats(1.0f); vec_float4 three = spu_splats(3.0f); vec_float4 x, y0, y1, y1_n1, y1_p1, y1_p2, y1_p3; vec_float4 mant, err, err_p1, err_p2, err_p3; vec_float4 out; /* Compute the mantissa of the result seperately from * the exponent to assure complete accuracy over the allowable * input range. The mantissa is computed for inputs in the * range [0.5, 2.0). */ x = spu_sel(in, one, mask); y0 = spu_rsqrte(x); /* Perform one iteration of the Newton-Raphsom method in single precision * arithmetic. */ y1 = spu_mul(spu_nmsub(x, spu_mul(y0, y0), three), spu_mul(y0, (vec_float4)(spu_sub((vec_uint4)(x), half)))); /* Correct the result for possible error. The range of error is -3 to +1. * Identify the extent of the error and correct for it. */ y1_p3 = (vec_float4)spu_add((vec_uint4)(y1), 3); y1_p2 = (vec_float4)spu_add((vec_uint4)(y1), 2); y1_p1 = (vec_float4)spu_add((vec_uint4)(y1), 1); y1_n1 = (vec_float4)spu_add((vec_uint4)(y1), -1); err = spu_nmsub(y1, y1, x); err_p1 = spu_nmsub(y1_p1, y1_p1, x); err_p2 = spu_nmsub(y1_p2, y1_p2, x); err_p3 = spu_nmsub(y1_p3, y1_p3, x); mant = spu_sel(y1_n1, y1, spu_cmpgt((vec_int4)(err), -1)); mant = spu_sel(mant, y1_p1, spu_cmpgt((vec_int4)(err_p1), -1)); mant = spu_sel(mant, y1_p2, spu_cmpgt((vec_int4)(err_p2), -1)); mant = spu_sel(mant, y1_p3, spu_cmpgt((vec_int4)(err_p3), -1)); /* Compute the expected exponent. If the exponent is zero or the input is * negative, then set the result to zero. */ exp = spu_rlmask(spu_add((vec_uint4)(in), (vec_uint4)(one)), -1); valid = spu_cmpgt(spu_and((vec_int4)(in), (vec_int4)(mask)), 0); /* Merge the computed exponent and mantissa. */ out = spu_and(spu_sel(mant, (vec_float4)(exp), spu_splats(0xFF800000)), (vec_float4)(valid)); return (out); } #endif /* _SQRTF4_H_ */ #endif /* __SPU__ */