comparison src/libsamplerate-0.1.8/M4/clip_mode.m4 @ 0:c7265573341e

Import initial set of sources

+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
+
+