[FFmpeg-cvslog] arm64: add cycle counter support

Janne Grunau git at videolan.org
Sat Jan 2 10:33:21 CET 2016


ffmpeg | branch: master | Janne Grunau <janne-libav at jannau.net> | Thu Dec  3 00:12:39 2015 +0100| [64034849dad8410bedbe1def4c533490fb85cc4a] | committer: Janne Grunau

arm64: add cycle counter support

The ISB (instruction synchronization barrier) might be too heavy for
START/STOPTIMER use but should be more accurate in checkasm where the
timing overhead is subtracted.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=64034849dad8410bedbe1def4c533490fb85cc4a
---

 libavutil/aarch64/timer.h |   44 ++++++++++++++++++++++++++++++++++++++++++++
 libavutil/timer.h         |    4 +++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/libavutil/aarch64/timer.h b/libavutil/aarch64/timer.h
new file mode 100644
index 0000000..382cfd9
--- /dev/null
+++ b/libavutil/aarch64/timer.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2015 Janne Grunau <janne-libav at jannau.net>
+ *
+ * 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
+ */
+
+#ifndef AVUTIL_AARCH64_TIMER_H
+#define AVUTIL_AARCH64_TIMER_H
+
+#include <stdint.h>
+#include "config.h"
+
+#if HAVE_INLINE_ASM
+
+#define AV_READ_TIME read_time
+
+static inline uint64_t read_time(void)
+{
+    uint64_t cycle_counter;
+    __asm__ volatile(
+        "isb                   \t\n"
+        "mrs %0, pmccntr_el0       "
+        : "=r"(cycle_counter) :: "memory" );
+
+    return cycle_counter;
+}
+
+#endif /* HAVE_INLINE_ASM */
+
+#endif /* AVUTIL_AARCH64_TIMER_H */
diff --git a/libavutil/timer.h b/libavutil/timer.h
index 0d93d7c..cc4c5a5 100644
--- a/libavutil/timer.h
+++ b/libavutil/timer.h
@@ -38,7 +38,9 @@
 
 #include "log.h"
 
-#if   ARCH_ARM
+#if   ARCH_AARCH64
+#   include "aarch64/timer.h"
+#elif ARCH_ARM
 #   include "arm/timer.h"
 #elif ARCH_BFIN
 #   include "bfin/timer.h"



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