Genesis-Plus-GX/source/sound/SRC/float_cast.h

/*
** Copyright (C) 2001-2008 Erik de Castro Lopo <erikd@mega-nerd.com>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU Lesser General Public License as published by
** the Free Software Foundation; either version 2.1 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU Lesser General Public License for more details.
**
** You should have received a copy of the GNU Lesser General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

/* Version 1.4 */

#ifndef FLOAT_CAST_HEADER
#define FLOAT_CAST_HEADER

/*============================================================================
**  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) ;
*/

#include "config.h"

/*
**  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.
*/

#define    HAVE_LRINT_REPLACEMENT  0

#if (HAVE_LRINT && HAVE_LRINTF)

  /*
  **  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>

#elif (defined (__CYGWIN__))

  #include  <math.h>

  #undef    HAVE_LRINT_REPLACEMENT
  #define    HAVE_LRINT_REPLACEMENT  1

  #undef  lrint
  #undef  lrintf

  #define  lrint  double2int
  #define  lrintf  float2int

  /*
  **  The native CYGWIN lrint and lrintf functions are buggy:
  **    http://sourceware.org/ml/cygwin/2005-06/msg00153.html
  **    http://sourceware.org/ml/cygwin/2005-09/msg00047.html
  **  and slow.
  **  These functions (pulled from the Public Domain MinGW math.h header)
  **  replace the native versions.
  */

  static inline long double2int (double in)
  {  long retval ;

    __asm__ __volatile__
    (  "fistpl %0"
      : "=m" (retval)
      : "t" (in)
      : "st"
      ) ;

    return retval ;
  } /* double2int */

  static inline long float2int (float in)
  {  long retval ;

    __asm__ __volatile__
    (  "fistpl %0"
      : "=m" (retval)
      : "t" (in)
      : "st"
      ) ;

    return retval ;
  } /* float2int */

#elif (defined (WIN32) || defined (_WIN32))

  #undef    HAVE_LRINT_REPLACEMENT
  #define    HAVE_LRINT_REPLACEMENT  1

  #include  <math.h>

  /*
  **  Win32 doesn't seem to have these functions.
  **  Therefore implement inline versions of these functions here.
  */

  __inline long int
  lrint (double flt)
  {  int intgr ;

    _asm
    {  fld flt
      fistp intgr
      } ;

    return intgr ;
  }

  __inline long int
  lrintf (float flt)
  {  int intgr ;

    _asm
    {  fld flt
      fistp intgr
      } ;

    return intgr ;
  }

#elif (defined (__MWERKS__) && defined (macintosh))

  /* This MacOS 9 solution was provided by Stephane Letz */

  #undef    HAVE_LRINT_REPLACEMENT
  #define    HAVE_LRINT_REPLACEMENT  1
  #include  <math.h>

  #undef  lrint
  #undef  lrintf

  #define  lrint  double2int
  #define  lrintf  float2int

  inline int
  float2int (register float in)
  {  long res [2] ;

    asm
    {  fctiw  in, in
      stfd   in, res
    }
    return res [1] ;
  } /* float2int */

  inline int
  double2int (register double in)
  {  long res [2] ;

    asm
    {  fctiw  in, in
      stfd   in, res
    }
    return res [1] ;
  } /* double2int */

#elif (defined (__MACH__) && defined (__APPLE__))

  /* For Apple MacOSX. */

  #undef    HAVE_LRINT_REPLACEMENT
  #define    HAVE_LRINT_REPLACEMENT  1
  #include  <math.h>

  #undef lrint
  #undef lrintf

  #define lrint  double2int
  #define lrintf  float2int

  inline static long
  float2int (register float in)
  {  int res [2] ;

    __asm__ __volatile__
    (  "fctiw  %1, %1\n\t"
      "stfd  %1, %0"
      : "=m" (res)  /* Output */
      : "f" (in)    /* Input */
      : "memory"
      ) ;

    return res [1] ;
  } /* lrintf */

  inline static long
  double2int (register double in)
  {  int res [2] ;

    __asm__ __volatile__
    (  "fctiw  %1, %1\n\t"
      "stfd  %1, %0"
      : "=m" (res)  /* Output */
      : "f" (in)    /* Input */
      : "memory"
      ) ;

    return res [1] ;
  } /* lrint */

#else
  #ifndef __sgi
  #warning "Don't have the functions lrint() and lrintf()."
  #warning "Replacing these functions with a standard C cast."
  #endif

  #include  <math.h>

  #define  lrint(dbl)    ((long) (dbl))
  #define  lrintf(flt)    ((long) (flt))

#endif


#endif /* FLOAT_CAST_HEADER */