forked from xuos/xiuos
136 lines
2.8 KiB
C
136 lines
2.8 KiB
C
/* Copyright JS Foundation and other contributors, http://js.foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is based on work under the following copyright and permission
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* notice:
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*
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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*
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* @(#)s_nextafter.c 1.3 95/01/18
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*/
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#include "jerry-math-internal.h"
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double
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nextafter (double x,
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double y)
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{
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int hx, hy, ix, iy;
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unsigned lx, ly;
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double_accessor ret;
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hx = __HI (x); /* high word of x */
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lx = __LO (x); /* low word of x */
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hy = __HI (y); /* high word of y */
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ly = __LO (y); /* low word of y */
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ix = hx & 0x7fffffff; /* |x| */
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iy = hy & 0x7fffffff; /* |y| */
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if (((ix >= 0x7ff00000) && ((ix - 0x7ff00000) | lx) != 0) /* x is nan */
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|| ((iy >= 0x7ff00000) && ((iy - 0x7ff00000) | ly) != 0)) /* y is nan */
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{
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return x + y;
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}
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if (x == y)
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{
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return x; /* x=y, return x */
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}
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if ((ix | lx) == 0)
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{ /* x == 0 */
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ret.as_int.hi = hy & 0x80000000; /* return +-minsubnormal */
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ret.as_int.lo = 1;
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y = ret.dbl * ret.dbl;
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if (y == ret.dbl)
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{
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return y;
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}
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else
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{
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return ret.dbl; /* raise underflow flag */
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}
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}
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if (hx >= 0)
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{ /* x > 0 */
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if (hx > hy || ((hx == hy) && (lx > ly)))
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{ /* x > y, x -= ulp */
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if (lx == 0)
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{
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hx -= 1;
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}
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lx -= 1;
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}
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else
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{ /* x < y, x += ulp */
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lx += 1;
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if (lx == 0)
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{
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hx += 1;
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}
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}
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}
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else
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{ /* x < 0 */
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if (hy >= 0 || hx > hy || ((hx == hy) && (lx > ly)))
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{ /* x < y, x -= ulp */
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if (lx == 0)
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{
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hx -= 1;
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}
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lx -= 1;
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}
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else
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{ /* x > y, x += ulp */
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lx += 1;
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if (lx == 0)
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{
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hx += 1;
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}
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}
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}
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hy = hx & 0x7ff00000;
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if (hy >= 0x7ff00000)
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{
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return x + x; /* overflow */
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}
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if (hy < 0x00100000)
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{ /* underflow */
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y = x * x;
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if (y != x)
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{ /* raise underflow flag */
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ret.as_int.hi = hx;
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ret.as_int.lo = lx;
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return ret.dbl;
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}
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}
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ret.as_int.hi = hx;
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ret.as_int.lo = lx;
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return ret.dbl;
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} /* nextafter */
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