newlib/libm/machine/i386/f_lrint.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 <<lrint>>, <<lrintf>>, <<lrintl>>---round and convert to long integer
  17 INDEX
  18         lrint
  19 INDEX
  20         lrintf
  21 INDEX
  22         lrintl
  23
  24 SYNOPSIS
  25         #include <math.h>
  26         long int lrint(double x);
  27         long int lrintf(float x);
  28         long int lrintl(long double x);
  29
  30 DESCRIPTION
  31 The <<lrint>>, <<lrintf>> and <<lrintl>> functions round <[x]> to the nearest integer value,
  32 according to the current rounding direction. If the rounded value is outside the
  33 range of the return type, the numeric result is unspecified. A range error may
  34 occur if the magnitude of <[x]> is too large.
  35
  36 RETURNS
  37 These functions return the rounded integer value of <[x]>.
  38 <<lrint>>, <<lrintf>> and <<lrintl>> return the result as a long integer.
  39
  40 PORTABILITY
  41 <<lrint>>, <<lrintf>>, and <<lrintl>> are ANSI.
  42 <<lrint>> and <<lrintf>> are available on all platforms.
  43 <<lrintl>> is only available on i386 platforms when hardware
  44 floating point support is available and when compiling with GCC.
  45
  46 */
  47
  48 /*
  49  * Fast math version of lrint(x)
  50  * Return x rounded to integral value according to the prevailing
  51  * rounding mode.
  52  * Method:
  53  *      Using inline x87 asms.
  54  * Exception:
  55  *      Governed by x87 FPCR.
  56  */
  57
  58 long int _f_lrint (double x)
  59 {
  60   long int _result;
  61   asm ("fistpl %0" : "=m" (_result) : "t" (x) : "st");
  62   return _result;
  63 }
  64
  65 #endif  /* !__GNUC__ || _SOFT_FLOAT */
  66