Emeric Vigier | eebea67 | 2012-08-06 17:36:30 -0400 | [diff] [blame] | 1 | dnl @synopsis AC_C_CLIP_MODE |
| 2 | dnl |
| 3 | dnl Determine the clipping mode when converting float to int. |
| 4 | dnl @version 1.0 May 17 2003 |
| 5 | dnl @author Erik de Castro Lopo <erikd AT mega-nerd DOT com> |
| 6 | dnl |
| 7 | dnl Permission to use, copy, modify, distribute, and sell this file for any |
| 8 | dnl purpose is hereby granted without fee, provided that the above copyright |
| 9 | dnl and this permission notice appear in all copies. No representations are |
| 10 | dnl made about the suitability of this software for any purpose. It is |
| 11 | dnl provided "as is" without express or implied warranty. |
| 12 | |
| 13 | |
| 14 | |
| 15 | |
| 16 | |
| 17 | |
| 18 | |
| 19 | dnl Find the clipping mode in the following way: |
| 20 | dnl 1) If we are not cross compiling test it. |
| 21 | dnl 2) IF we are cross compiling, assume that clipping isn't done correctly. |
| 22 | |
| 23 | AC_DEFUN([AC_C_CLIP_MODE], |
| 24 | [AC_CACHE_CHECK(processor clipping capabilities, |
| 25 | ac_cv_c_clip_type, |
| 26 | |
| 27 | # Initialize to unknown |
| 28 | ac_cv_c_clip_positive=unknown |
| 29 | ac_cv_c_clip_negative=unknown |
| 30 | |
| 31 | |
| 32 | if test $ac_cv_c_clip_positive = unknown ; then |
| 33 | AC_TRY_RUN( |
| 34 | [[ |
| 35 | #define _ISOC9X_SOURCE 1 |
| 36 | #define _ISOC99_SOURCE 1 |
| 37 | #define __USE_ISOC99 1 |
| 38 | #define __USE_ISOC9X 1 |
| 39 | #include <math.h> |
| 40 | int main (void) |
| 41 | { double fval ; |
| 42 | int k, ival ; |
| 43 | |
| 44 | fval = 1.0 * 0x7FFFFFFF ; |
| 45 | for (k = 0 ; k < 100 ; k++) |
| 46 | { ival = (lrint (fval)) >> 24 ; |
| 47 | if (ival != 127) |
| 48 | return 1 ; |
| 49 | |
| 50 | fval *= 1.2499999 ; |
| 51 | } ; |
| 52 | |
| 53 | return 0 ; |
| 54 | } |
| 55 | ]], |
| 56 | ac_cv_c_clip_positive=yes, |
| 57 | ac_cv_c_clip_positive=no, |
| 58 | ac_cv_c_clip_positive=unknown |
| 59 | ) |
| 60 | |
| 61 | AC_TRY_RUN( |
| 62 | [[ |
| 63 | #define _ISOC9X_SOURCE 1 |
| 64 | #define _ISOC99_SOURCE 1 |
| 65 | #define __USE_ISOC99 1 |
| 66 | #define __USE_ISOC9X 1 |
| 67 | #include <math.h> |
| 68 | int main (void) |
| 69 | { double fval ; |
| 70 | int k, ival ; |
| 71 | |
| 72 | fval = -8.0 * 0x10000000 ; |
| 73 | for (k = 0 ; k < 100 ; k++) |
| 74 | { ival = (lrint (fval)) >> 24 ; |
| 75 | if (ival != -128) |
| 76 | return 1 ; |
| 77 | |
| 78 | fval *= 1.2499999 ; |
| 79 | } ; |
| 80 | |
| 81 | return 0 ; |
| 82 | } |
| 83 | ]], |
| 84 | ac_cv_c_clip_negative=yes, |
| 85 | ac_cv_c_clip_negative=no, |
| 86 | ac_cv_c_clip_negative=unknown |
| 87 | ) |
| 88 | fi |
| 89 | |
| 90 | if test $ac_cv_c_clip_positive = yes ; then |
| 91 | ac_cv_c_clip_positive=1 |
| 92 | else |
| 93 | ac_cv_c_clip_positive=0 |
| 94 | fi |
| 95 | |
| 96 | if test $ac_cv_c_clip_negative = yes ; then |
| 97 | ac_cv_c_clip_negative=1 |
| 98 | else |
| 99 | ac_cv_c_clip_negative=0 |
| 100 | fi |
| 101 | |
| 102 | [[ |
| 103 | case "$ac_cv_c_clip_positive$ac_cv_c_clip_negative" in |
| 104 | "00") |
| 105 | ac_cv_c_clip_type="none" |
| 106 | ;; |
| 107 | "10") |
| 108 | ac_cv_c_clip_type="positive" |
| 109 | ;; |
| 110 | "01") |
| 111 | ac_cv_c_clip_type="negative" |
| 112 | ;; |
| 113 | "11") |
| 114 | ac_cv_c_clip_type="both" |
| 115 | ;; |
| 116 | esac |
| 117 | ]] |
| 118 | |
| 119 | ) |
| 120 | ] |
| 121 | |
| 122 | )# AC_C_CLIP_MODE |
| 123 | |
| 124 | |