[FFmpeg-devel,2/5] additional math.h functions for djgpp

diff --git a/compat/djgpp/math.c b/compat/djgpp/math.c
new file mode 100644
index 0000000000..777b879e01
--- /dev/null
+++ b/compat/djgpp/math.c
@@ -0,0 +1,47 @@ 
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <math.h>
+
+#define FUN(name, type, op) \
+type name(type x, type y) \
+{ \
+    if (fpclassify(x) == FP_NAN) return y; \
+    if (fpclassify(y) == FP_NAN) return x; \
+    return x op y ? x : y; \
+}
+
+FUN(fmin, double, <)
+FUN(fmax, double, >)
+FUN(fminf, float, <)
+FUN(fmaxf, float, >)
+
+long double fmodl(long double x, long double y)
+{
+    return fmod(x, y);
+}
+
+long double scalbnl(long double x, int exp)
+{
+    return scalbn(x, exp);
+}
+
+long double copysignl(long double x, long double y)
+{
+    return copysign(x, y);
+}
diff --git a/compat/djgpp/math.h b/compat/djgpp/math.h
new file mode 100644
index 0000000000..4c02ea9c40
--- /dev/null
+++ b/compat/djgpp/math.h
@@ -0,0 +1,25 @@ 
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+double fmin(double, double);
+double fmax(double, double);
+float fminf(float, float);
+float fmaxf(float, float);
+long double fmodl(long double, long double);
+long double scalbnl(long double, int);
+long double copysignl(long double, long double);
diff --git a/configure b/configure
index 9ceb4a0c76..6d58d30df6 100755
--- a/configure
+++ b/configure
@@ -5466,6 +5466,8 @@  EOF
     elif test_${pfx}cpp_condition sys/version.h "defined __DJGPP__"; then
         eval ${pfx}libc_type=djgpp
         add_cppflags -U__STRICT_ANSI__
+        add_cflags "-include $source_path/compat/djgpp/math.h"
+        add_compat djgpp/math.o
     fi
     test_${pfx}cc <<EOF
 #include <time.h>
diff --git a/tests/ref/fate/source b/tests/ref/fate/source
index b35f016127..0c98a0638a 100644
--- a/tests/ref/fate/source
+++ b/tests/ref/fate/source
@@ -28,6 +28,7 @@  compat/avisynth/avxsynth_c.h
 compat/avisynth/windowsPorts/basicDataTypeConversions.h
 compat/avisynth/windowsPorts/windows2linux.h
 compat/cuda/dynlink_loader.h
+compat/djgpp/math.h
 compat/float/float.h
 compat/float/limits.h
 Use of av_clip() where av_clip_uintp2() could be used: