[SCM] libav/experimental: Work around broken floating point limits on some systems.

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit e854b8f9f4097a3c560b746895e9da6721aa4cdb
Author: Anton Khirnov <anton at khirnov.net>
Date:   Thu Nov 14 12:19:04 2013 +0100

    Work around broken floating point limits on some systems.
    
    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
        [....]
    }

diff --git a/libavcodec/dct32.h b/compat/float/float.h
similarity index 67%
copy from libavcodec/dct32.h
copy to compat/float/float.h
index 110338d..c69f728 100644
--- a/libavcodec/dct32.h
+++ b/compat/float/float.h
@@ -1,4 +1,6 @@
 /*
+ * 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
@@ -16,10 +18,18 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#ifndef AVCODEC_DCT32_H
-#define AVCODEC_DCT32_H
+#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
 
-void ff_dct32_float(float *dst, const float *src);
-void ff_dct32_fixed(int *dst, const int *src);
+#undef  DBL_MAX
+#define DBL_MAX ((double)1.79769313486231570815e+308L)
 
+#undef  DBL_MIN
+#define DBL_MIN ((double)2.22507385850720138309e-308L)
 #endif
diff --git a/libavcodec/fft_fixed.c b/compat/float/limits.h
similarity index 87%
copy from libavcodec/fft_fixed.c
copy to compat/float/limits.h
index bad4821..9150bc8 100644
--- a/libavcodec/fft_fixed.c
+++ b/compat/float/limits.h
@@ -1,4 +1,6 @@
 /*
+ * 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
@@ -16,5 +18,5 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#define FFT_FLOAT 0
-#include "fft_template.c"
+#include_next <limits.h>
+#include <float.h>
diff --git a/configure b/configure
index 766df99..c98f0bd 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 "$headers" "char c[2 * !!($condition) - 1]" "$@" && enable "$name"
+}
+
 require(){
     name="$1"
     header="$2"
@@ -1360,6 +1370,7 @@ HAVE_LIST="
     fast_clz
     fast_cmov
     fcntl
+    flt_lim
     fork
     getaddrinfo
     gethrtime
@@ -3536,6 +3547,9 @@ 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'
 }

-- 
Libav/FFmpeg packaging