--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dynamin/core/environment.d	Mon Jun 15 22:10:48 2009 -0500
@@ -0,0 +1,132 @@
+// Written in the D programming language
+// www.digitalmars.com/d/
+
+/*
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is the Dynamin library.
+ *
+ * The Initial Developer of the Original Code is Jordan Miner.
+ * Portions created by the Initial Developer are Copyright (C) 2006-2009
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Jordan Miner <jminer7@gmail.com>
+ *
+ */
+
+module dynamin.core.environment;
+
+import dynamin.all_core;
+import dynamin.core_backend;
+
+/**
+ * Contains static methods to access information about the computer the
+ * application is running on.
+ */
+static class Environment {
+static:
+private:
+	mixin EnvironmentBackend;
+public:
+	/**
+	 * Returns the time in milliseconds since the program was started.
+	 * On Windows XP, this time is updated every millisecond.
+	 * On Linux, this time is usually updated every millisecond, but
+	 * occasionally may take 5 to 10 milliseconds.
+	 * This is the author's dream time function because
+	 *
+	 * $(OL
+	 * $(LI It is accurate to 1 millisecond.)
+	 * $(LI It works correctly on multiple core computers.)
+	 * $(LI It is unaffected by changes to the system time.)
+	 * $(LI It never wraps to zero.)
+	 * )
+	 *
+	 * On my 1.3 GHz celeron, this function can be called about 480 times
+	 * in one millisecond under Windows and about 380 times in one millisecond
+	 * under Linux.
+	 *
+	 * TODO: make sure it works with multiple cores, although I'm sure it does
+	 */
+	long runningTime() {
+		return backend_runningTime;
+	}
+	/**
+	 * Returns the system time in milliseconds since January 1, 1970 UTC.
+	 * On Windows XP, this time is only updated every 15.625 milliseconds.
+	 *
+	 * On my 1.3 GHz celeron, this function can be called about 12,000 times
+	 * in one millisecond under Windows and about 460 times in one millisecond
+	 * under Linux.
+	 */
+	long systemTime() {
+		return backend_systemTime;
+	}
+	/**
+	 * Gets the number of logical processors on this computer. A logical
+	 * processor can either be a different physical processor or simply
+	 * another core in the same processor. Even a single core hyper-threaded
+	 * processor is considered to have two logical processors.
+	 * Returns: the number of logical processors
+	 */
+	int processorCount() {
+		return backend_processorCount;
+	}
+	/**
+	 * The number returned by this method can be used to measure the
+	 * time between two calls. This method uses the highest resolution
+	 * timer available.
+	 *
+	 * On my 1.3 GHz celeron, this function can be called about 500 times
+	 * in one millisecond under Windows.
+	 *
+	 * Returns: the current time in milliseconds
+	 *
+	 * Note: Under Windows, this is implemented using QueryPerformanceCounter().
+	 * QueryPerformanceCounter() gets the time counter from the processor.
+	 * On processors with multiple cores (such as an Althon X2 or a Core 2 Duo),
+	 * the time counter for each core may be a few milliseconds different.
+	 * (Microsoft's documentation says this is due to bugs in the BIOS or HAL.)
+	 * Since QueryPerformanceCounter() can get the time from either core,
+	 * the time between two calls made within the same millisecond can be off.
+	 * For example, on my Althon X2 computer, the difference between cores
+	 * is usually 60 ms. If two calls to QueryPerformanceCounter() are made
+	 * in the same millisecond, there is a possiblity that the second one
+	 * will return a time 60 ms smaller than the first.
+	 * Under Linux, this is implemented using gettimeofday(), which has no
+	 * problems with multiple cores and is accurate.
+	 * One way to fix this inaccuracy is by only allowing the thread to
+	 * use one processor. Another problem is that this time will run slightly
+	 * faster or slower than the system time.
+	 */
+	private long processorTime() {
+		return backend_processorTime;
+	}
+}
+
+unittest {
+	auto startTime = Environment.runningTime;
+	assert(startTime > 0);
+	auto time = startTime;
+	const SAMPLE = 50;
+	// makes sure that RunningTime does not go backwards
+	for(int i = 0; i < SAMPLE;) {
+		auto time2 = Environment.runningTime;
+		assert(time2 >= time);
+		if(time2 > time) {
+			time = time2;
+			++i;
+		}
+	}
+	//printf("avg accuracy: %.1f ms\n", (time-startTime)/cast(float)SAMPLE);
+}
+