kc3-lang/SDL/src/libm/s_scalbn.c

Branch : - branch - v2.28 - tag -

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  Commit

• Author : Sam Lantinga
  Date : 2020-01-29 20:09:16
  Hash : 0897f235
  Message : Fixed compiler warning

• src/libm/s_scalbn.c

• /*
   * ====================================================
   * 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_libm.h"
  #include "math_private.h"
  #include <limits.h>
  
  #ifdef __WATCOMC__ /* Watcom defines huge=__huge */
  #undef huge
  #endif
  
  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 = (int32_t)(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)
  
  
  double scalbn(double x, int n)
  {
  	return scalbln(x, n);
  }
  libm_hidden_def(scalbn)