| /* -------------------------------------------------------------- */ |
| /* (C)Copyright 2006,2008, */ |
| /* 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. */ |
| /* */ |
| /* 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 _HYPOTD2_H_ |
| #define _HYPOTD2_H_ 1 |
| |
| #include <spu_intrinsics.h> |
| #include "sqrtd2.h" |
| |
| /* |
| * FUNCTION |
| * vector double hypotd2(vector double x, vector double y) |
| * |
| * DESCRIPTION |
| * The function hypotd2 returns a double vector in which each element is |
| * the square root of the sum of the squares of the corresponding |
| * elements of x and y. |
| * |
| * The purpose of this function is to avoid overflow during |
| * intermediate calculations, and therefore it is slower than |
| * simply calcualting sqrt(x^2 + y^2). |
| * |
| * This function is performed by factoring out the larger of the 2 |
| * input exponents and moving this factor outside of the sqrt calculation. |
| * This will minimize the possibility of over/underflow when the square |
| * of the values are calculated. Think of it as normalizing the larger |
| * input to the range [1,2). |
| * |
| * Special Cases: |
| * - hypot(x, +/-0) returns |x| |
| * - hypot(+/- infinity, y) returns +infinity |
| * - hypot(+/- infinity, NaN) returns +infinity |
| * |
| */ |
| static __inline vector double _hypotd2(vector double x, vector double y) |
| { |
| vector unsigned long long emask = spu_splats(0x7FF0000000000000ull); |
| vector unsigned long long mmask = spu_splats(0x000FFFFFFFFFFFFFull); |
| vector signed long long bias = spu_splats(0x3FF0000000000000ll); |
| vector double oned = spu_splats(1.0); |
| vector double sbit = spu_splats(-0.0); |
| vector double inf = (vector double)spu_splats(0x7FF0000000000000ull); |
| vector double max, max_e, max_m; |
| vector double min, min_e, min_m; |
| vector unsigned long long xgty; |
| vector double sum; |
| vector double result; |
| |
| /* Only need absolute values for this function */ |
| x = spu_andc(x, sbit); |
| y = spu_andc(y, sbit); |
| xgty = spu_cmpgt(x,y); |
| |
| max = spu_sel(y,x,xgty); |
| min = spu_sel(x,y,xgty); |
| |
| /* Extract the exponents and mantissas */ |
| max_e = (vec_double2)spu_and((vec_ullong2)max, emask); |
| max_m = (vec_double2)spu_and((vec_ullong2)max, mmask); |
| min_e = (vec_double2)spu_and((vec_ullong2)min, emask); |
| min_m = (vec_double2)spu_and((vec_ullong2)min, mmask); |
| |
| /* Factor-out max exponent here by subtracting from min exponent */ |
| vec_llong2 min_e_int = (vec_llong2)spu_sub((vec_int4)min_e, (vec_int4)max_e); |
| min_e = (vec_double2)spu_add((vec_int4)min_e_int, (vec_int4)bias); |
| |
| /* If the new min exponent is too small, just set it to 0. It |
| * wouldn't contribute to the final result in either case. |
| */ |
| min_e = spu_sel(min_e, sbit, spu_cmpgt(sbit, min_e)); |
| |
| /* Combine new exponents with original mantissas */ |
| max = spu_or(oned, max_m); |
| min = spu_or(min_e, min_m); |
| |
| sum = _sqrtd2(spu_madd(max, max, spu_mul(min, min))); |
| sum = spu_mul(max_e, sum); |
| |
| /* Special case: x = +/- infinity */ |
| result = spu_sel(sum, inf, spu_cmpeq(x, inf)); |
| |
| return result; |
| } |
| |
| #endif /* _HYPOTD2_H_ */ |
| #endif /* __SPU__ */ |