[docs] Add CANJNI docs

hal/src/main/java/edu/wpi/first/hal/can/CANJNI.java

@@ -9,6 +9,11 @@
 import java.nio.ByteBuffer;
 import java.nio.IntBuffer;
 
+/**
+ * CAN API HAL JNI Functions.
+ *
+ * @see "hal/CAN.h"
+ */
 @SuppressWarnings("MethodName")
 public class CANJNI extends JNIWrapper {
   public static final int CAN_SEND_PERIOD_NO_REPEAT = 0;
@@ -18,18 +23,68 @@ public class CANJNI extends JNIWrapper {
   public static final int CAN_IS_FRAME_REMOTE = 0x80000000;
   public static final int CAN_IS_FRAME_11BIT = 0x40000000;
 
+  /**
+   * Sends a CAN message.
+   *
+   * @param messageID The ID of the CAN message.
+   * @param data The data bytes to be sent.
+   * @param periodMs The period in milliseconds at which to send the message, use {@link
+   *     #CAN_SEND_PERIOD_NO_REPEAT} for a single send.
+   */
   public static native void FRCNetCommCANSessionMuxSendMessage(
       int messageID, byte[] data, int periodMs);
 
+  /**
+   * Receives a CAN message.
+   *
+   * @param messageID store for the received message ID (output parameter).
+   * @param messageIDMask the message ID mask to look for
+   * @param timeStamp the packet received timestamp (based off of CLOCK_MONOTONIC) (output
+   *     parameter).
+   * @return The data bytes of the received message.
+   */
   public static native byte[] FRCNetCommCANSessionMuxReceiveMessage(
       IntBuffer messageID, int messageIDMask, ByteBuffer timeStamp);
 
+  /**
+   * Retrieves the current status of the CAN bus.
+   *
+   * @param status The CANStatus object to hold the retrieved status.
+   */
   public static native void getCANStatus(CANStatus status);
 
+  /**
+   * Opens a new CAN stream session for receiving CAN messages with specified filters.
+   *
+   * @param messageID The CAN messageID to match against. The bits of the messageID are bitwise
+   *     ANDed with the messageIDMask.
+   * @param messageIDMask The CAN messageIDMask is a bit-wise mask of bits in the messageID to match
+   *     against. This allows matching against multiple frames. For example, providing an messageID
+   *     of 0x2050001 and a mask of 0x1FFF003F would match all REV motor controller frames for a
+   *     device with CAN ID 1. Providing a mask of 0x1FFFFFFF means that only the exact messageID
+   *     will be matched. Providing a mask of 0 would match any frame of any type.
+   * @param maxMessages The maximum number of messages that can be buffered in the session.
+   * @return The handle to the opened CAN stream session.
+   */
   public static native int openCANStreamSession(int messageID, int messageIDMask, int maxMessages);
 
+  /**
+   * Closes a CAN stream session.
+   *
+   * @param sessionHandle The handle of the CAN stream session to be closed.
+   */
   public static native void closeCANStreamSession(int sessionHandle);
 
+  /**
+   * Reads messages from a CAN stream session.
+   *
+   * @param sessionHandle The handle of the CAN stream session.
+   * @param messages An array to hold the CANStreamMessage objects (output parameter).
+   * @param messagesToRead The number of messages to read from the session.
+   * @return The number of messages read into the buffer
+   * @throws CANStreamOverflowException If the number of messages to read exceeds the capacity of
+   *     the provided messages array.
+   */
   public static native int readCANStreamSession(
       int sessionHandle, CANStreamMessage[] messages, int messagesToRead)
       throws CANStreamOverflowException;