Imported Upstream version 1.1~hg20130304upstream/1.1_hg20130304

1 files changed, 34 insertions, 0 deletions

diff --git a/src/pkg/runtime/time_plan9_386.c b/src/pkg/runtime/time_plan9_386.c
new file mode 100644
index 000000000..a29d45715
--- /dev/null
+++ b/src/pkg/runtime/time_plan9_386.c
@@ -0,0 +1,34 @@
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "os_GOOS.h"
+
+int64
+runtime·nanotime(void)
+{
+	static int32 fd = -1;
+	byte b[8];
+	uint32 hi, lo;
+
+	// As long as all goroutines share the same file
+	// descriptor table we can get away with using
+	// just a static fd.  Without a lock the file can
+	// be opened twice but that's okay.
+	//
+	// Using /dev/bintime gives us a latency on the
+	// order of ten microseconds between two calls.
+	//
+	// The naïve implementation (without the cached
+	// file descriptor) is roughly four times slower
+	// in 9vx on a 2.16 GHz Intel Core 2 Duo.
+
+	if(fd < 0 && (fd = runtime·open((byte*)"/dev/bintime", OREAD|OCEXEC)) < 0)
+		return 0;
+	if(runtime·pread(fd, b, sizeof b, 0) != sizeof b)
+		return 0;
+	hi = b[0]<<24 | b[1]<<16 | b[2]<<8 | b[3];
+	lo = b[4]<<24 | b[5]<<16 | b[6]<<8 | b[7];
+	return (int64)hi<<32 | (int64)lo;
+}