generic/lib/math/clc_ldexp.cl

/*
 * Copyright (c) 2014 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 "config.h"
#include "../clcmacro.h"
#include "math.h"

_CLC_DEF _CLC_OVERLOAD float __clc_ldexp(float x, int n) {

	if (!__clc_fp32_subnormals_supported()) {

		// This treats subnormals as zeros
		int i = as_int(x);
		int e = (i >> 23) & 0xff;
		int m = i & 0x007fffff;
		int s = i & 0x80000000;
		int v = add_sat(e, n);
		v = clamp(v, 0, 0xff);
		int mr = e == 0 | v == 0 | v == 0xff ? 0 : m;
		int c = e == 0xff;
		mr = c ? m : mr;
		int er = c ? e : v;
		er = e ? er : e;
		return as_float( s | (er << 23) | mr );
	}

	/* supports denormal values */
	const int multiplier = 24;
	float val_f;
	uint val_ui;
	uint sign;
	int exponent;
	val_ui = as_uint(x);
	sign = val_ui & 0x80000000;
	val_ui = val_ui & 0x7fffffff;/* remove the sign bit */
	int val_x = val_ui;

	exponent = val_ui >> 23; /* get the exponent */
	int dexp = exponent;

	/* denormal support */
	int fbh = 127 - (as_uint((float)(as_float(val_ui | 0x3f800000) - 1.0f)) >> 23);
	int dexponent = 25 - fbh;
	uint dval_ui = (( (val_ui << fbh) & 0x007fffff) | (dexponent << 23));
	int ex = dexponent + n - multiplier;
	dexponent = ex;
	uint val = sign | (ex << 23) | (dval_ui & 0x007fffff);
	int ex1 = dexponent + multiplier;
	ex1 = -ex1 +25;
	dval_ui = (((dval_ui & 0x007fffff )| 0x800000) >> ex1);
	dval_ui = dexponent > 0 ? val :dval_ui;
	dval_ui = dexponent > 254 ? 0x7f800000 :dval_ui;  /*overflow*/
	dval_ui = dexponent < -multiplier ? 0 : dval_ui;  /*underflow*/
	dval_ui = dval_ui | sign;
	val_f = as_float(dval_ui);

	exponent += n;

	val = sign | (exponent << 23) | (val_ui & 0x007fffff);
	ex1 = exponent + multiplier;
	ex1 = -ex1 +25;
	val_ui = (((val_ui & 0x007fffff )| 0x800000) >> ex1);
	val_ui = exponent > 0 ? val :val_ui;
	val_ui = exponent > 254 ? 0x7f800000 :val_ui;  /*overflow*/
	val_ui = exponent < -multiplier ? 0 : val_ui;  /*underflow*/
	val_ui = val_ui | sign;

	val_ui = dexp == 0? dval_ui : val_ui;
	val_f = as_float(val_ui);

	val_f = isnan(x) | isinf(x) | val_x == 0 ? x : val_f;
	return val_f;
}

#ifdef cl_khr_fp64

#pragma OPENCL EXTENSION cl_khr_fp64 : enable

_CLC_DEF _CLC_OVERLOAD double __clc_ldexp(double x, int n) {
	long l = as_ulong(x);
	int e = (l >> 52) & 0x7ff;
	long s = l & 0x8000000000000000;

	ulong ux = as_ulong(x * 0x1.0p+53);
	int de = ((int)(ux >> 52) & 0x7ff) - 53;
	int c = e == 0;
	e = c ? de: e;

	ux = c ? ux : l;

	int v = e + n;
	v = clamp(v, -0x7ff, 0x7ff);

	ux &= ~EXPBITS_DP64;

	double mr = as_double(ux | ((ulong)(v+53) << 52));
	mr = mr * 0x1.0p-53;

	mr = v > 0  ? as_double(ux | ((ulong)v << 52)) : mr;

	mr = v == 0x7ff ? as_double(s | PINFBITPATT_DP64)  : mr;
	mr = v < -53 ? as_double(s) : mr;

	mr  = ((n == 0) | isinf(x) | (x == 0) ) ? x : mr;
	return mr;
}

#endif