76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
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/*
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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 SunPro, 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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*/
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/*
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* rint(x)
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* Return x rounded to integral value according to the prevailing
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* rounding mode.
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* Method:
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* Using floating addition.
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* Exception:
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* Inexact flag raised if x not equal to rint(x).
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*/
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#include <fenv.h>
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#include <math.h>
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#include <math-barriers.h>
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#include <math_private.h>
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#include <fenv_private.h>
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#include <libm-alias-double.h>
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#include <math-use-builtins.h>
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double
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__nearbyint (double x)
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{
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#if USE_NEARBYINT_BUILTIN
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return __builtin_nearbyint (x);
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#else
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/* Use generic implementation. */
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static const double
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TWO52[2] = {
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4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
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-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
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};
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fenv_t env;
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int64_t i0, sx;
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int32_t j0;
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EXTRACT_WORDS64 (i0, x);
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sx = (i0 >> 63) & 1;
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j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
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if (__glibc_likely (j0 < 52))
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{
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if (j0 < 0)
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{
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libc_feholdexcept (&env);
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double w = TWO52[sx] + math_opt_barrier (x);
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double t = w - TWO52[sx];
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math_force_eval (t);
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libc_fesetenv (&env);
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return copysign (t, x);
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}
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}
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else
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{
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if (j0 == 0x400)
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return x + x; /* inf or NaN */
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else
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return x; /* x is integral */
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}
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libc_feholdexcept (&env);
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double w = TWO52[sx] + math_opt_barrier (x);
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double t = w - TWO52[sx];
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math_force_eval (t);
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libc_fesetenv (&env);
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return t;
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#endif /* ! USE_NEARBYINT_BUILTIN */
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}
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libm_alias_double (__nearbyint, nearbyint)
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