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
[....]
}
---
Martynas is not replying to pings (and we'd have to support current broken
systems anyway), so resending this. I've discovered the same problem in musl
(where it's already fixed), so amended the description to not be bsd-specific.
---
compat/float/float.h | 35 +++++++++++++++++++++++++++++++++++
compat/float/limits.h | 22 ++++++++++++++++++++++
configure | 14 ++++++++++++++
3 files changed, 71 insertions(+)
create mode 100644 compat/float/float.h
create mode 100644 compat/float/limits.h
diff --git a/compat/float/float.h b/compat/float/float.h
new file mode 100644
index 0000000..c69f728
--- /dev/null
+++ b/compat/float/float.h
@@ -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
diff --git a/compat/float/limits.h b/compat/float/limits.h
new file mode 100644
index 0000000..9150bc8
--- /dev/null
+++ b/compat/float/limits.h
@@ -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>
diff --git a/configure b/configure
index d12427d..c53453a 100755
--- a/configure
+++ b/configure
@@ -994,6 +994,16 @@ check_builtin(){
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 "$headers" "char c[!!($condition) - 1]" "$@" && enable
"$name"
+}
+
require(){
name="$1"
header="$2"
@@ -1356,6 +1366,7 @@ HAVE_LIST="
fast_clz
fast_cmov
fcntl
+ flt_lim
fork
getaddrinfo
gethrtime
@@ -3530,6 +3541,9 @@ if enabled_all ccc libc_glibc; then
add_ldflags -Wl,-z,now # calls to libots crash without this
fi
+check_compile_assert flt_lim "float.h limits.h" "DBL_MAX == (double)DBL_MAX" ||
+ add_cppflags '-I\$(SRC_PATH)/compat/float'
+
esc(){
echo "$*" | sed 's/%/%25/g;s/:/%3a/g'
}
--
1.7.10.4
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