124 lines
5.1 KiB
C
124 lines
5.1 KiB
C
/* -------------------------------------------------------------- */
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/* (C)Copyright 2007,2008, */
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/* International Business Machines Corporation */
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/* All Rights Reserved. */
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/* */
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/* Redistribution and use in source and binary forms, with or */
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/* without modification, are permitted provided that the */
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/* following conditions are met: */
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/* */
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/* - Redistributions of source code must retain the above copyright*/
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/* notice, this list of conditions and the following disclaimer. */
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/* */
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/* - Redistributions in binary form must reproduce the above */
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/* copyright notice, this list of conditions and the following */
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/* disclaimer in the documentation and/or other materials */
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/* provided with the distribution. */
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/* */
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/* - Neither the name of IBM Corporation nor the names of its */
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/* contributors may be used to endorse or promote products */
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/* derived from this software without specific prior written */
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/* permission. */
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/* */
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/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND */
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/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, */
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/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF */
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/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE */
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/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR */
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/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */
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/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT */
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/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; */
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/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) */
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/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN */
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/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR */
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/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, */
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/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
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/* -------------------------------------------------------------- */
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/* PROLOG END TAG zYx */
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#ifdef __SPU__
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#ifndef _NEXTAFTERD2_H_
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#define _NEXTAFTERD2_H_ 1
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#include <spu_intrinsics.h>
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/*
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* FUNCTION
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* vector double _nextafterd2(vector double x, vector double y)
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*
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* DESCRIPTION
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* The nextafterf4 function returns a vector containing the next representable
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* floating-point number after the element of x, in the direction of the
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* corresponding element y.
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*
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* Special Cases:
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* - nextafter(NaN, y) = NaN
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* - nextafter(x, NaN) = NaN
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* - x = largest finite value, y = infinity, result is undefined
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* - x = largest finite negative value, y = -infinity, result is undefined
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* - x != y, and result = 0, considered an underflow
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*
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*/
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static __inline vector double _nextafterd2(vector double x, vector double y)
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{
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vec_double2 n1ulp = (vec_double2)spu_splats(0x8000000000000001ull);
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vector unsigned char mov_carry = {0x80,0x80,0x80, 7, 0x80,0x80,0x80,0x80,
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0x80,0x80,0x80,15, 0x80,0x80,0x80,0x80};
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vec_double2 zerod = spu_splats(0.0);
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vec_llong2 one = spu_splats(1ll);
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vec_ullong2 xlt0, xgty, xeqy, xeq0;
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vec_llong2 xllong;
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vec_int4 carry;
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vec_llong2 delta, deltap1;
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vec_double2 result;
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/* Compiler Bug. Replace xtmp/ytmp with x/y when spu_cmpgt(x,y) doesn't change x/y!*/
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volatile vec_double2 xtmp = x;
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volatile vec_double2 ytmp = y;
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/*
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* The idea here is to treat x as a signed long long value, which allows us to
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* add or subtact one to/from it to get the next representable value.
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*/
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xeq0 = spu_cmpeq(xtmp, zerod);
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xlt0 = spu_cmpgt(zerod, xtmp);
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xeqy = spu_cmpeq(xtmp, ytmp);
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xgty = spu_cmpgt(xtmp, ytmp);
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/* If x = -0.0, set x = 0.0 */
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x = spu_andc(x, (vec_double2)xeq0);
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xllong = (vec_llong2)x;
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/* Determine value to add to x */
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delta = (vec_llong2)spu_xor(xgty, xlt0);
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//deltap1 = delta + one;
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carry = spu_genc((vec_int4)delta, (vec_int4)one);
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carry = spu_shuffle(carry, carry, mov_carry);
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deltap1 = (vec_llong2)spu_addx((vec_int4)delta, (vec_int4)one, (vec_int4)carry);
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delta = spu_sel(deltap1, delta, (vec_ullong2)delta);
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//xllong = xllong + delta;
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carry = spu_genc((vec_int4)xllong, (vec_int4)delta);
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carry = spu_shuffle(carry, carry, mov_carry);
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xllong = (vec_llong2)spu_addx((vec_int4)xllong, (vec_int4)delta, (vec_int4)carry);
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/* Fix the case of x = 0, and answer should be -1 ulp */
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result = spu_sel((vec_double2)xllong, n1ulp, spu_and((vec_ullong2)delta, xeq0));
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/*
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* Special Cases
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*/
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/* x = y */
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result = spu_sel(result, y, xeqy);
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return result;
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}
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#endif /* _NEXTAFTERD2_H_ */
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#endif /* __SPU__ */
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