[Libva] [PATCH] add replacement for log2f when not available

[groleo at gmail.com]

From: Adrian Marius Negreanu <adrian.m.negreanu at intel.com>

Signed-off-by: Adrian Marius Negreanu <adrian.m.negreanu at intel.com>
---
 configure.ac          | 1 +
 src/gen6_mfc_common.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/configure.ac b/configure.ac
index 176519d..a9ed8d5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -65,6 +65,7 @@ AC_C_BIGENDIAN
 AC_HEADER_STDC
 AC_SYS_LARGEFILE
 AC_CHECK_LIB([m], [sin])
+AC_CHECK_FUNCS([log2f])
 
 LIBVA_PACKAGE_VERSION=libva_package_version
 AC_SUBST(LIBVA_PACKAGE_VERSION)
diff --git a/src/gen6_mfc_common.c b/src/gen6_mfc_common.c
index bb5d360..1d57075 100644
--- a/src/gen6_mfc_common.c
+++ b/src/gen6_mfc_common.c
@@ -62,6 +62,10 @@
 
 #define BRC_PI_0_5 1.5707963267948966192313216916398
 
+#ifndef HAVE_LOG2F
+#define log2f(x) (logf(x)/(float)M_LN2)
+#endif
+
 static void
 intel_mfc_bit_rate_control_context_init(struct encode_state *encode_state, 
                                        struct gen6_mfc_context *mfc_context)
-- 
1.8.0