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- /*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
- /*
- * scalbln(double x, long n)
- * scalbln(x,n) returns x * 2**n computed by exponent
- * manipulation rather than by actually performing an
- * exponentiation or a multiplication.
- */
- #include "math.h"
- #include "math_private.h"
- #include <limits.h>
- static const double
- two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
- twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
- huge = 1.0e+300,
- tiny = 1.0e-300;
- double scalbln(double x, long n)
- {
- int32_t k, hx, lx;
- EXTRACT_WORDS(hx, lx, x);
- k = (hx & 0x7ff00000) >> 20; /* extract exponent */
- if (k == 0) { /* 0 or subnormal x */
- if ((lx | (hx & 0x7fffffff)) == 0)
- return x; /* +-0 */
- x *= two54;
- GET_HIGH_WORD(hx, x);
- k = ((hx & 0x7ff00000) >> 20) - 54;
- }
- if (k == 0x7ff)
- return x + x; /* NaN or Inf */
- k = k + n;
- if (k > 0x7fe)
- return huge * copysign(huge, x); /* overflow */
- if (n < -50000)
- return tiny * copysign(tiny, x); /* underflow */
- if (k > 0) { /* normal result */
- SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
- return x;
- }
- if (k <= -54) {
- if (n > 50000) /* in case integer overflow in n+k */
- return huge * copysign(huge, x); /* overflow */
- return tiny * copysign(tiny, x); /* underflow */
- }
- k += 54; /* subnormal result */
- SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
- return x * twom54;
- }
- libm_hidden_def(scalbln)
- #if LONG_MAX == INT_MAX
- strong_alias_untyped(scalbln,scalbn)
- #else
- double scalbn(double x, int n)
- {
- return scalbln(x, n);
- }
- #endif
- libm_hidden_def(scalbn)
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