shithub: libsamplerate

ref: 09d00868afafbbeb7632e764ed658ca3a6d60d4a
dir: /m4/clip_mode.m4/

dnl @synopsis AC_C_CLIP_MODE
dnl
dnl Determine the clipping mode when converting float to int.
dnl @version 1.0	May 17 2003
dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com>
dnl
dnl Permission to use, copy, modify, distribute, and sell this file for any 
dnl purpose is hereby granted without fee, provided that the above copyright 
dnl and this permission notice appear in all copies.  No representations are
dnl made about the suitability of this software for any purpose.  It is 
dnl provided "as is" without express or implied warranty.







dnl Find the clipping mode in the following way:
dnl    1) If we are not cross compiling test it.
dnl    2) IF we are cross compiling, assume that clipping isn't done correctly.

AC_DEFUN([AC_C_CLIP_MODE],
[AC_CACHE_CHECK(processor clipping capabilities, 
	ac_cv_c_clip_type,

# Initialize to unknown
ac_cv_c_clip_positive=unknown
ac_cv_c_clip_negative=unknown


if test $ac_cv_c_clip_positive = unknown ; then
	AC_TRY_RUN(
	[[
	#define	_ISOC9X_SOURCE	1
	#define _ISOC99_SOURCE	1
	#define	__USE_ISOC99	1
	#define __USE_ISOC9X	1
	#include <math.h>
	int main (void)
	{	double	fval ;
		int k, ival ;

		fval = 1.0 * 0x7FFFFFFF ;
		for (k = 0 ; k < 100 ; k++)
		{	ival = (lrint (fval)) >> 24 ;
			if (ival != 127)
				return 1 ;
		
			fval *= 1.2499999 ;
			} ;
		
			return 0 ;
		}
		]],
		ac_cv_c_clip_positive=yes,
		ac_cv_c_clip_positive=no,
		ac_cv_c_clip_positive=unknown
		)

	AC_TRY_RUN(
	[[
	#define	_ISOC9X_SOURCE	1
	#define _ISOC99_SOURCE	1
	#define	__USE_ISOC99	1
	#define __USE_ISOC9X	1
	#include <math.h>
	int main (void)
	{	double	fval ;
		int k, ival ;

		fval = -8.0 * 0x10000000 ;
		for (k = 0 ; k < 100 ; k++)
		{	ival = (lrint (fval)) >> 24 ;
			if (ival != -128)
				return 1 ;
		
			fval *= 1.2499999 ;
			} ;
		
			return 0 ;
		}
		]],
		ac_cv_c_clip_negative=yes,
		ac_cv_c_clip_negative=no,
		ac_cv_c_clip_negative=unknown
		)
	fi

if test $ac_cv_c_clip_positive = yes ; then
	ac_cv_c_clip_positive=1
else
	ac_cv_c_clip_positive=0
	fi

if test $ac_cv_c_clip_negative = yes ; then
	ac_cv_c_clip_negative=1
else
	ac_cv_c_clip_negative=0
	fi

[[
case "$ac_cv_c_clip_positive$ac_cv_c_clip_negative" in
	"00")
		ac_cv_c_clip_type="none"
		;;
	"10")
		ac_cv_c_clip_type="positive"
		;;
	"01")
		ac_cv_c_clip_type="negative"
		;;
	"11")
		ac_cv_c_clip_type="both"
		;;
	esac
	]]

)
]

)# AC_C_CLIP_MODE