newlib-cygwin/newlib/libm/machine/i386/f_lrint.c

70 lines
1.7 KiB
C

/*
* ====================================================
* x87 FP implementation contributed to Newlib by
* Dave Korn, November 2007. This file is placed in the
* public domain. Permission to use, copy, modify, and
* distribute this software is freely granted.
* ====================================================
*/
#if defined(__GNUC__) && !defined(_SOFT_FLOAT)
#include <math.h>
/*
FUNCTION
<<lrint>>, <<lrintf>>, <<lrintl>>---round and convert to long integer
INDEX
lrint
INDEX
lrintf
INDEX
lrintl
ANSI_SYNOPSIS
#include <math.h>
long int lrint(double x);
long int lrintf(float x);
long int lrintl(long double x);
TRAD_SYNOPSIS
ANSI-only.
DESCRIPTION
The <<lrint>>, <<lrintf>> and <<lrintl>> functions round <[x]> to the nearest integer value,
according to the current rounding direction. If the rounded value is outside the
range of the return type, the numeric result is unspecified. A range error may
occur if the magnitude of <[x]> is too large.
RETURNS
These functions return the rounded integer value of <[x]>.
<<lrint>>, <<lrintf>> and <<lrintl>> return the result as a long integer.
PORTABILITY
<<lrint>>, <<lrintf>>, and <<lrintl>> are ANSI.
<<lrint>> and <<lrintf>> are available on all platforms.
<<lrintl>> is only available on i386 platforms when hardware
floating point support is available and when compiling with GCC.
*/
/*
* Fast math version of lrint(x)
* Return x rounded to integral value according to the prevailing
* rounding mode.
* Method:
* Using inline x87 asms.
* Exception:
* Governed by x87 FPCR.
*/
long int _f_lrint (double x)
{
long int _result;
asm ("fistpl %0" : "=m" (_result) : "t" (x) : "st");
return _result;
}
#endif /* !__GNUC__ || _SOFT_FLOAT */