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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [common/] [s_lround.c] - Blame information for rev 207

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1 207 jeremybenn 
/*
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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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FUNCTION
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<<lround>>, <<lroundf>>, <<llround>>, <<llroundf>>--round to integer, to nearest
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INDEX
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        lround
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INDEX
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        lroundf
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INDEX
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        llround
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INDEX
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        llroundf
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ANSI_SYNOPSIS
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        #include <math.h>
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        long int lround(double <[x]>);
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        long int lroundf(float <[x]>);
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        long long int llround(double <[x]>);
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        long long int llroundf(float <[x]>);
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DESCRIPTION
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        The <<lround>> and <<llround>> functions round their argument to the
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        nearest integer value, rounding halfway cases away from zero, regardless
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        of the current rounding direction.  If the rounded value is outside the
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        range of the return type, the numeric result is unspecified (depending
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        upon the floating-point implementation, not the library).  A range
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        error may occur if the magnitude of x is too large.
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RETURNS
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<[x]> rounded to an integral value as an integer.
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SEEALSO
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See the <<round>> functions for the return being the same floating-point type
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as the argument.  <<lrint>>, <<llrint>>.
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PORTABILITY
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ANSI C, POSIX
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*/
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#include "fdlibm.h"
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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        long int lround(double x)
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#else
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        long int lround(x)
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        double x;
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#endif
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{
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  __int32_t sign, exponent_less_1023;
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  /* Most significant word, least significant word. */
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  __uint32_t msw, lsw;
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  long int result;
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  EXTRACT_WORDS(msw, lsw, x);
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  /* Extract sign. */
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  sign = ((msw & 0x80000000) ? -1 : 1);
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  /* Extract exponent field. */
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  exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
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  msw &= 0x000fffff;
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  msw |= 0x00100000;
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  if (exponent_less_1023 < 20)
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    {
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      if (exponent_less_1023 < 0)
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        {
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          if (exponent_less_1023 < -1)
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            return 0;
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          else
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            return sign;
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        }
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      else
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        {
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          msw += 0x80000 >> exponent_less_1023;
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          result = msw >> (20 - exponent_less_1023);
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        }
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    }
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  else if (exponent_less_1023 < (8 * sizeof (long int)) - 1)
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    {
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      if (exponent_less_1023 >= 52)
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        result = ((long int) msw << (exponent_less_1023 - 20)) | (lsw << (exponent_less_1023 - 52));
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      else
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        {
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          unsigned int tmp = lsw + (0x80000000 >> (exponent_less_1023 - 20));
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          if (tmp < lsw)
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            ++msw;
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          result = ((long int) msw << (exponent_less_1023 - 20)) | (tmp >> (52 - exponent_less_1023));
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        }
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    }
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  else
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    /* Result is too large to be represented by a long int. */
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    return (long int)x;
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  return sign * result;
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}
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#endif /* _DOUBLE_IS_32BITS */

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