newlib/libm/machine/i386/f_rint.c

   1 /*
   2  * ====================================================
   3  * x87 FP implementation contributed to Newlib by
   4  * Dave Korn, November 2007.  This file is placed in the
   5  * public domain.  Permission to use, copy, modify, and
   6  * distribute this software is freely granted.
   7  * ====================================================
   8  */
   9
  10 #if defined(__GNUC__) && !defined(_SOFT_FLOAT)
  11
  12 #include <math.h>
  13
  14 /*
  15 FUNCTION
  16 <<rint>>, <<rintf>>, <<rintl>>---round to integer
  17 INDEX
  18         rint
  19 INDEX
  20         rintf
  21 INDEX
  22         rintl
  23
  24 SYNOPSIS
  25         #include <math.h>
  26         double rint(double x);
  27         float rintf(float x);
  28         long double rintl(long double x);
  29
  30 DESCRIPTION
  31 The <<rint>>, <<rintf>> and <<rintl>> functions round <[x]> to an integer value
  32 in floating-point format, using the current rounding direction.  They may
  33 raise the inexact exception if the result differs in value from the argument.
  34
  35 RETURNS
  36 These functions return the rounded integer value of <[x]>.
  37
  38 PORTABILITY
  39 <<rint>>, <<rintf>> and <<rintl>> are ANSI.
  40 <<rint>> and <<rintf>> are available on all platforms.
  41 <<rintl>> is only available on i386 platforms when hardware
  42 floating point support is available and when compiling with GCC.
  43
  44 */
  45
  46 /*
  47  * Fast math version of rint(x)
  48  * Return x rounded to integral value according to the prevailing
  49  * rounding mode.
  50  * Method:
  51  *      Using inline x87 asms.
  52  * Exception:
  53  *      Governed by x87 FPCR.
  54  */
  55
  56 double _f_rint (double x)
  57 {
  58   double _result;
  59   asm ("frndint" : "=t" (_result) : "0" (x));
  60   return _result;
  61 }
  62
  63 #endif  /* !__GNUC__ || _SOFT_FLOAT */
  64