From dfde8a34e5419ac99265e3ecc2e82f378674128a Mon Sep 17 00:00:00 2001
From: Justin Ruggles <justin.ruggles@gmail.com>
Date: Fri, 26 Oct 2012 14:48:40 -0400
Subject: lavu: add av_ctz() for trailing zero bit count

---
 libavutil/Makefile  |  2 +-
 libavutil/intmath.c | 39 +++++++++++++++++++++++++++++++++++++
 libavutil/intmath.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 libavutil/log2.c    | 34 ---------------------------------
 libavutil/version.h |  2 +-
 5 files changed, 96 insertions(+), 36 deletions(-)
 create mode 100644 libavutil/intmath.c
 delete mode 100644 libavutil/log2.c

(limited to 'libavutil')

diff --git a/libavutil/Makefile b/libavutil/Makefile
index 45f8e9076c..d4ffd5e7d6 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -67,10 +67,10 @@ OBJS = adler32.o                                                        \
        float_dsp.o                                                      \
        imgutils.o                                                       \
        intfloat_readwrite.o                                             \
+       intmath.o                                                        \
        lfg.o                                                            \
        lls.o                                                            \
        log.o                                                            \
-       log2.o                                                           \
        log2_tab.o                                                       \
        mathematics.o                                                    \
        md5.o                                                            \
diff --git a/libavutil/intmath.c b/libavutil/intmath.c
new file mode 100644
index 0000000000..8db425c6e9
--- /dev/null
+++ b/libavutil/intmath.c
@@ -0,0 +1,39 @@
+/*
+ * 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 "intmath.h"
+
+/* undef these to get the function prototypes from common.h */
+#undef av_log2
+#undef av_log2_16bit
+#include "common.h"
+
+int av_log2(unsigned v)
+{
+    return ff_log2(v);
+}
+
+int av_log2_16bit(unsigned v)
+{
+    return ff_log2_16bit(v);
+}
+
+int av_ctz(int v)
+{
+    return ff_ctz(v);
+}
diff --git a/libavutil/intmath.h b/libavutil/intmath.h
index 2cb313240b..a5ee6525ee 100644
--- a/libavutil/intmath.h
+++ b/libavutil/intmath.h
@@ -85,6 +85,61 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
 #define av_log2       ff_log2
 #define av_log2_16bit ff_log2_16bit
 
+/**
+ * @}
+ */
+
+/**
+ * @addtogroup lavu_math
+ * @{
+ */
+
+#if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
+#ifndef ff_ctz
+#define ff_ctz(v) __builtin_ctz(v)
+#endif
+#endif
+
+#ifndef ff_ctz
+#define ff_ctz ff_ctz_c
+static av_always_inline av_const int ff_ctz_c(int v)
+{
+    int c;
+
+    if (v & 0x1)
+        return 0;
+
+    c = 1;
+    if (!(v & 0xffff)) {
+        v >>= 16;
+        c += 16;
+    }
+    if (!(v & 0xff)) {
+        v >>= 8;
+        c += 8;
+    }
+    if (!(v & 0xf)) {
+        v >>= 4;
+        c += 4;
+    }
+    if (!(v & 0x3)) {
+        v >>= 2;
+        c += 2;
+    }
+    c -= v & 0x1;
+
+    return c;
+}
+#endif
+
+/**
+ * Trailing zero bit count.
+ *
+ * @param v  input value. If v is 0, the result is undefined.
+ * @return   the number of trailing 0-bits
+ */
+int av_ctz(int v);
+
 /**
  * @}
  */
diff --git a/libavutil/log2.c b/libavutil/log2.c
deleted file mode 100644
index 18c1b40aaa..0000000000
--- a/libavutil/log2.c
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * 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 "intmath.h"
-
-/* undef these to get the function prototypes from common.h */
-#undef av_log2
-#undef av_log2_16bit
-#include "common.h"
-
-int av_log2(unsigned v)
-{
-    return ff_log2(v);
-}
-
-int av_log2_16bit(unsigned v)
-{
-    return ff_log2_16bit(v);
-}
diff --git a/libavutil/version.h b/libavutil/version.h
index ae7fa7abeb..1659dbd537 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -37,7 +37,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 52
-#define LIBAVUTIL_VERSION_MINOR  0
+#define LIBAVUTIL_VERSION_MINOR  1
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
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