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Work around broken floating point limits on some systems.

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The values of {FLT,DBL}_{MAX,MIN} macros on some systems (older musl
libc, some BSD flavours) are not exactly representable, i.e.
(double)DBL_MAX == DBL_MAX is false
This violates (at least some interpretations of) the C99 standard and
breaks code (e.g. in vf_fps) like
double f = DBL_MAX;
[...]
if (f == DBL_MAX) { // f has not been changed yet
    [....]
}
This commit is contained in:
Anton Khirnov 2013-11-14 12:19:04 +01:00
parent 8cafeb8bca
commit e854b8f9f4
3 changed files with 71 additions and 0 deletions
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35
compat/float/float.h Normal file
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@ -0,0 +1,35 @@
/*
* Work around broken floating point limits on some systems.
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include_next <float.h>
#ifdef FLT_MAX
#undef FLT_MAX
#define FLT_MAX 3.40282346638528859812e+38F
#undef FLT_MIN
#define FLT_MIN 1.17549435082228750797e-38F
#undef DBL_MAX
#define DBL_MAX ((double)1.79769313486231570815e+308L)
#undef DBL_MIN
#define DBL_MIN ((double)2.22507385850720138309e-308L)
#endif

22
compat/float/limits.h Normal file
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@ -0,0 +1,22 @@
/*
* Work around broken floating point limits on some systems.
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include_next <limits.h>
#include <float.h>

14
configure vendored
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@ -994,6 +994,16 @@ check_builtin(){
check_code ld "$headers" "$builtin" "$@" && enable "$name" check_code ld "$headers" "$builtin" "$@" && enable "$name"
} }
check_compile_assert(){
log check_compile_assert "$@"
name=$1
headers=$2
condition=$3
shift 3
disable "$name"
check_code cc "$headers" "char c[2 * !!($condition) - 1]" "$@" && enable "$name"
}
require(){ require(){
name="$1" name="$1"
header="$2" header="$2"
@ -1360,6 +1370,7 @@ HAVE_LIST="
fast_clz fast_clz
fast_cmov fast_cmov
fcntl fcntl
flt_lim
fork fork
getaddrinfo getaddrinfo
gethrtime gethrtime
@ -3536,6 +3547,9 @@ if enabled_all ccc libc_glibc; then
add_ldflags -Wl,-z,now # calls to libots crash without this add_ldflags -Wl,-z,now # calls to libots crash without this
fi fi
check_compile_assert flt_lim "float.h limits.h" "DBL_MAX == (double)DBL_MAX" ||
add_cppflags '-I\$(SRC_PATH)/compat/float'
esc(){ esc(){
echo "$*" | sed 's/%/%25/g;s/:/%3a/g' echo "$*" | sed 's/%/%25/g;s/:/%3a/g'
} }