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annotate src/libsndfile-1.0.25/M4/clip_mode.m4 @ 0:c7265573341e

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Import initial set of sources
author Chris Cannam
date Mon, 18 Mar 2013 14:12:14 +0000
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Chris@0 1 dnl @synopsis MN_C_CLIP_MODE
Chris@0 2 dnl
Chris@0 3 dnl Determine the clipping mode when converting float to int.
Chris@0 4 dnl @version 1.0 May 17 2003
Chris@0 5 dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com>
Chris@0 6 dnl
Chris@0 7 dnl Permission to use, copy, modify, distribute, and sell this file for any
Chris@0 8 dnl purpose is hereby granted without fee, provided that the above copyright
Chris@0 9 dnl and this permission notice appear in all copies. No representations are
Chris@0 10 dnl made about the suitability of this software for any purpose. It is
Chris@0 11 dnl provided "as is" without express or implied warranty.
Chris@0 12
Chris@0 13
Chris@0 14
Chris@0 15
Chris@0 16
Chris@0 17
Chris@0 18
Chris@0 19 dnl Find the clipping mode in the following way:
Chris@0 20 dnl 1) If we are not cross compiling test it.
Chris@0 21 dnl 2) IF we are cross compiling, assume that clipping isn't done correctly.
Chris@0 22
Chris@0 23 AC_DEFUN([MN_C_CLIP_MODE],
Chris@0 24 [AC_CACHE_CHECK(processor clipping capabilities,
Chris@0 25 ac_cv_c_clip_type,
Chris@0 26
Chris@0 27 # Initialize to unknown
Chris@0 28 ac_cv_c_clip_positive=unknown
Chris@0 29 ac_cv_c_clip_negative=unknown
Chris@0 30
Chris@0 31
Chris@0 32 if test $ac_cv_c_clip_positive = unknown ; then
Chris@0 33 AC_TRY_RUN(
Chris@0 34 [[
Chris@0 35 #define _ISOC9X_SOURCE 1
Chris@0 36 #define _ISOC99_SOURCE 1
Chris@0 37 #define __USE_ISOC99 1
Chris@0 38 #define __USE_ISOC9X 1
Chris@0 39 #include <math.h>
Chris@0 40 int main (void)
Chris@0 41 { double fval ;
Chris@0 42 int k, ival ;
Chris@0 43
Chris@0 44 fval = 1.0 * 0x7FFFFFFF ;
Chris@0 45 for (k = 0 ; k < 100 ; k++)
Chris@0 46 { ival = (lrint (fval)) >> 24 ;
Chris@0 47 if (ival != 127)
Chris@0 48 return 1 ;
Chris@0 49
Chris@0 50 fval *= 1.2499999 ;
Chris@0 51 } ;
Chris@0 52
Chris@0 53 return 0 ;
Chris@0 54 }
Chris@0 55 ]],
Chris@0 56 ac_cv_c_clip_positive=yes,
Chris@0 57 ac_cv_c_clip_positive=no,
Chris@0 58 ac_cv_c_clip_positive=unknown
Chris@0 59 )
Chris@0 60
Chris@0 61 AC_TRY_RUN(
Chris@0 62 [[
Chris@0 63 #define _ISOC9X_SOURCE 1
Chris@0 64 #define _ISOC99_SOURCE 1
Chris@0 65 #define __USE_ISOC99 1
Chris@0 66 #define __USE_ISOC9X 1
Chris@0 67 #include <math.h>
Chris@0 68 int main (void)
Chris@0 69 { double fval ;
Chris@0 70 int k, ival ;
Chris@0 71
Chris@0 72 fval = -8.0 * 0x10000000 ;
Chris@0 73 for (k = 0 ; k < 100 ; k++)
Chris@0 74 { ival = (lrint (fval)) >> 24 ;
Chris@0 75 if (ival != -128)
Chris@0 76 return 1 ;
Chris@0 77
Chris@0 78 fval *= 1.2499999 ;
Chris@0 79 } ;
Chris@0 80
Chris@0 81 return 0 ;
Chris@0 82 }
Chris@0 83 ]],
Chris@0 84 ac_cv_c_clip_negative=yes,
Chris@0 85 ac_cv_c_clip_negative=no,
Chris@0 86 ac_cv_c_clip_negative=unknown
Chris@0 87 )
Chris@0 88 fi
Chris@0 89
Chris@0 90 if test $ac_cv_c_clip_positive = yes ; then
Chris@0 91 ac_cv_c_clip_positive=1
Chris@0 92 else
Chris@0 93 ac_cv_c_clip_positive=0
Chris@0 94 fi
Chris@0 95
Chris@0 96 if test $ac_cv_c_clip_negative = yes ; then
Chris@0 97 ac_cv_c_clip_negative=1
Chris@0 98 else
Chris@0 99 ac_cv_c_clip_negative=0
Chris@0 100 fi
Chris@0 101
Chris@0 102 [[
Chris@0 103 case "$ac_cv_c_clip_positive$ac_cv_c_clip_negative" in
Chris@0 104 "00")
Chris@0 105 ac_cv_c_clip_type="none"
Chris@0 106 ;;
Chris@0 107 "10")
Chris@0 108 ac_cv_c_clip_type="positive"
Chris@0 109 ;;
Chris@0 110 "01")
Chris@0 111 ac_cv_c_clip_type="negative"
Chris@0 112 ;;
Chris@0 113 "11")
Chris@0 114 ac_cv_c_clip_type="both"
Chris@0 115 ;;
Chris@0 116 esac
Chris@0 117 ]]
Chris@0 118
Chris@0 119 )
Chris@0 120 ]
Chris@0 121
Chris@0 122 )# MN_C_CLIP_MODE
Chris@0 123
Chris@0 124