From 8e707169a118ad0808f6ff2da80cb17161030258 Mon Sep 17 00:00:00 2001
From: Dustin Spicuzza <dustin@virtualroadside.com>
Date: Sun, 30 Nov 2014 23:51:01 -0500
Subject: [PATCH] Add hasPeriodPassed function to java, for parity with C++
 Timer API

Change-Id: I0f9a2714f20deaaccce610bd3eec58409eac3104
---
 .../java/edu/wpi/first/wpilibj/Timer.java     | 24 +++++++++++++++++++
 .../first/wpilibj/internal/HardwareTimer.java | 18 ++++++++++++++
 .../wpi/first/wpilibj/internal/SimTimer.java  | 18 ++++++++++++++
 3 files changed, 60 insertions(+)

diff --git a/wpilibj/wpilibJava/src/main/java/edu/wpi/first/wpilibj/Timer.java b/wpilibj/wpilibJava/src/main/java/edu/wpi/first/wpilibj/Timer.java
index a35be8c397..8a1391b859 100644
--- a/wpilibj/wpilibJava/src/main/java/edu/wpi/first/wpilibj/Timer.java
+++ b/wpilibj/wpilibJava/src/main/java/edu/wpi/first/wpilibj/Timer.java
@@ -113,6 +113,19 @@ public class Timer {
 		timer.stop();
 	}
 
+	/**
+	 * Check if the period specified has passed and if it has, advance the start
+	 * time by that period. This is useful to decide if it's time to do periodic
+	 * work without drifting later by the time it took to get around to checking.
+	 *
+	 * @param period The period to check for (in seconds).
+	 * @return If the period has passed.
+	 */
+	public boolean hasPeriodPassed(double period)
+	{
+		return timer.hasPeriodPassed(period);
+	}
+
 	public interface Interface {
 		/**
 		 * Get the current time from the timer. If the clock is running it is derived from
@@ -143,5 +156,16 @@ public class Timer {
 		 * looking at the system clock.
 		 */
 		public void stop();
+
+
+		/**
+		 * Check if the period specified has passed and if it has, advance the start
+		 * time by that period. This is useful to decide if it's time to do periodic
+		 * work without drifting later by the time it took to get around to checking.
+		 *
+		 * @param period The period to check for (in seconds).
+		 * @return If the period has passed.
+		 */
+		public boolean hasPeriodPassed(double period);
 	}
 }
diff --git a/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/internal/HardwareTimer.java b/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/internal/HardwareTimer.java
index b5a301a057..0ba6339930 100644
--- a/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/internal/HardwareTimer.java
+++ b/wpilibj/wpilibJavaDevices/src/main/java/edu/wpi/first/wpilibj/internal/HardwareTimer.java
@@ -120,5 +120,23 @@ public class HardwareTimer implements Timer.StaticInterface {
 	        m_accumulatedTime = temp;
 	        m_running = false;
 	    }
+
+        /**
+         * Check if the period specified has passed and if it has, advance the start
+         * time by that period. This is useful to decide if it's time to do periodic
+         * work without drifting later by the time it took to get around to checking.
+         *
+         * @param period The period to check for (in seconds).
+         * @return If the period has passed.
+         */
+        public synchronized boolean hasPeriodPassed(double period) {
+            if (get() > period) {
+                // Advance the start time by the period.
+                // Don't set it to the current time... we want to avoid drift.
+                m_startTime += period;
+                return true;
+            }
+            return false;
+        }
     }
 }
diff --git a/wpilibj/wpilibJavaSim/src/main/java/edu/wpi/first/wpilibj/internal/SimTimer.java b/wpilibj/wpilibJavaSim/src/main/java/edu/wpi/first/wpilibj/internal/SimTimer.java
index 8314a3ffbe..cbc75eb668 100644
--- a/wpilibj/wpilibJavaSim/src/main/java/edu/wpi/first/wpilibj/internal/SimTimer.java
+++ b/wpilibj/wpilibJavaSim/src/main/java/edu/wpi/first/wpilibj/internal/SimTimer.java
@@ -149,5 +149,23 @@ public class SimTimer implements Timer.StaticInterface {
 	        m_accumulatedTime = temp;
 	        m_running = false;
 	    }
+
+        /**
+         * Check if the period specified has passed and if it has, advance the start
+         * time by that period. This is useful to decide if it's time to do periodic
+         * work without drifting later by the time it took to get around to checking.
+         *
+         * @param period The period to check for (in seconds).
+         * @return If the period has passed.
+         */
+        public synchronized boolean hasPeriodPassed(double period) {
+            if (get() > period) {
+                // Advance the start time by the period.
+                // Don't set it to the current time... we want to avoid drift.
+                m_startTime += period;
+                return true;
+            }
+            return false;
+        }
     }
 }