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/*
* Copyright (c) 2014,2015 Advanced Micro Devices, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <clc/clc.h>
#include "math.h"
#include "../clcmacro.h"
_CLC_OVERLOAD _CLC_DEF float exp2(float x) {
// Reduce x
const float ln2HI = 0x1.62e300p-1f;
const float ln2LO = 0x1.2fefa2p-17f;
float t = rint(x);
int p = (int)t;
float tt = x - t;
float hi = tt * ln2HI;
float lo = tt * ln2LO;
// Evaluate poly
t = hi + lo;
tt = t*t;
float v = mad(tt,
-mad(tt,
mad(tt,
mad(tt,
mad(tt, 0x1.637698p-25f, -0x1.bbd41cp-20f),
0x1.1566aap-14f),
-0x1.6c16c2p-9f),
0x1.555556p-3f),
t);
float y = 1.0f - (((-lo) - MATH_DIVIDE(t * v, 2.0f - v)) - hi);
// Scale by 2^p
float r = as_float(as_int(y) + (p << 23));
const float ulim = 128.0f;
const float llim = -126.0f;
r = x < llim ? 0.0f : r;
r = x < ulim ? r : as_float(0x7f800000);
return isnan(x) ? x : r;
}
_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, float, exp2, float)
#ifdef cl_khr_fp64
#include "exp_helper.h"
#pragma OPENCL EXTENSION cl_khr_fp64 : enable
_CLC_OVERLOAD _CLC_DEF double exp2(double x) {
const double R_LN2 = 0x1.62e42fefa39efp-1; // ln(2)
const double R_1_BY_64 = 1.0 / 64.0;
int n = convert_int(x * 64.0);
double r = R_LN2 * fma(-R_1_BY_64, (double)n, x);
return __clc_exp_helper(x, -1074.0, 1024.0, r, n);
}
_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, exp2, double)
#endif
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