ref: 137f3366bc0ea0a9c24420ce779435866f00f44e
dir: /libcelt/float_cast.h/
/*
** Copyright (C) 2001 Erik de Castro Lopo <erikd AT mega-nerd DOT com>
**
** Permission to use, copy, modify, distribute, and sell this file for any
** purpose is hereby granted without fee, provided that the above copyright
** and this permission notice appear in all copies. No representations are
** made about the suitability of this software for any purpose. It is
** provided "as is" without express or implied warranty.
*/
/* Version 1.1 */
#ifndef FLOAT_CAST_H
#define FLOAT_CAST_H
/*============================================================================
** On Intel Pentium processors (especially PIII and probably P4), converting
** from float to int is very slow. To meet the C specs, the code produced by
** most C compilers targeting Pentium needs to change the FPU rounding mode
** before the float to int conversion is performed.
**
** Changing the FPU rounding mode causes the FPU pipeline to be flushed. It
** is this flushing of the pipeline which is so slow.
**
** Fortunately the ISO C99 specifications define the functions lrint, lrintf,
** llrint and llrintf which fix this problem as a side effect.
**
** On Unix-like systems, the configure process should have detected the
** presence of these functions. If they weren't found we have to replace them
** here with a standard C cast.
*/
/*
** The C99 prototypes for lrint and lrintf are as follows:
**
** long int lrintf (float x) ;
** long int lrint (double x) ;
*/
/* The presence of the required functions are detected during the configure
** process and the values HAVE_LRINT and HAVE_LRINTF are set accordingly in
** the config.h file.
*/
#if (HAVE_LRINTF)
/*#if 0*/
/* These defines enable functionality introduced with the 1999 ISO C
** standard. They must be defined before the inclusion of math.h to
** engage them. If optimisation is enabled, these functions will be
** inlined. With optimisation switched off, you have to link in the
** maths library using -lm.
*/
#define _ISOC9X_SOURCE 1
#define _ISOC99_SOURCE 1
#define __USE_ISOC9X 1
#define __USE_ISOC99 1
#include <math.h>
#define float2int(x) lrintf(x)
#elif (defined(HAVE_LRINT))
#define _ISOC9X_SOURCE 1
#define _ISOC99_SOURCE 1
#define __USE_ISOC9X 1
#define __USE_ISOC99 1
#include <math.h>
#define float2int(x) lrint(x)
#elif (defined (WIN32) || defined (_WIN32))
#include <math.h>
/* Win32 doesn't seem to have these functions.
** Therefore implement inline versions of these functions here.
*/
__inline long int
float2int (float flt)
{ int intgr;
_asm
{ fld flt
fistp intgr
} ;
return intgr ;
}
#else
#ifdef __GNUC__ /* supported by gcc, but not by all other compilers*/
#warning "Don't have the functions lrint() and lrintf ()."
#warning "Replacing these functions with a standard C cast."
#endif /* __GNUC__ */
#include <math.h>
#define float2int(flt) ((int)(floor(.5+flt)))
#endif
#endif /* FLOAT_CAST_H */