newlib/libm/machine/i386/f_llrint.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 #ifdef __GNUC__
  11 #if !defined(_SOFT_FLOAT)
  12
  13 #include <math.h>
  14
  15 /*
  16 FUNCTION
  17 <<llrint>>, <<llrintf>>, <<llrintl>>---round and convert to long long integer
  18 INDEX
  19         llrint
  20 INDEX
  21         llrintf
  22 INDEX
  23         llrintl
  24
  25 SYNOPSIS
  26         #include <math.h>
  27         long long int llrint(double x);
  28         long long int llrintf(float x);
  29         long long int llrintl(long double x);
  30
  31 DESCRIPTION
  32 The <<llrint>>, <<llrintf>> and <<llrintl>> functions round <[x]> to the nearest integer value,
  33 according to the current rounding direction. If the rounded value is outside the
  34 range of the return type, the numeric result is unspecified. A range error may
  35 occur if the magnitude of <[x]> is too large.
  36
  37 RETURNS
  38 These functions return the rounded integer value of <[x]>.
  39 <<llrint>>, <<llrintf>> and <<llrintl>> return the result as a long long integer.
  40
  41 PORTABILITY
  42 <<llrint>>, <<llrintf>> and <<llrintl>> are ANSI.
  43 The fast math versions of <<llrint>>, <<llrintf>> and <<llrintl>> are only
  44 available on i386 platforms when hardware floating point support is available
  45 and when compiling with GCC.
  46
  47 */
  48
  49 /*
  50  * Fast math version of llrint(x)
  51  * Return x rounded to integral value according to the prevailing
  52  * rounding mode.
  53  * Method:
  54  *      Using inline x87 asms.
  55  * Exception:
  56  *      Governed by x87 FPCR.
  57  */
  58
  59 long long int _f_llrint (double x)
  60 {
  61   long long int _result;
  62   asm ("fistpll %0" : "=m" (_result) : "t" (x) : "st");
  63   return _result;
  64 }
  65
  66 #endif /* !_SOFT_FLOAT */
  67 #endif /* __GNUC__ */