[wpimath] Add protobuf/struct for trivial types (#5935)

This implements de/serialization for the types that aren't templated (SwerveDriveKinematics) in C++ or where there is no trivial way to go round-trip (Splines) for the messages.

wpimath/src/main/java/edu/wpi/first/math/system/plant/DCMotor.java

@@ -4,6 +4,8 @@
 
 package edu.wpi.first.math.system.plant;
 
+import edu.wpi.first.math.system.plant.proto.DCMotorProto;
+import edu.wpi.first.math.system.plant.struct.DCMotorStruct;
 import edu.wpi.first.math.util.Units;
 
 /** Holds the constants for a DC motor. */
@@ -17,6 +19,9 @@ public class DCMotor {
   public final double KvRadPerSecPerVolt;
   public final double KtNMPerAmp;
 
+  public static final DCMotorProto proto = new DCMotorProto();
+  public static final DCMotorStruct struct = new DCMotorStruct();
+
   /**
    * Constructs a DC motor.
    *

wpimath/src/main/java/edu/wpi/first/math/system/plant/proto/DCMotorProto.java

@@ -0,0 +1,47 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.math.system.plant.proto;
+
+import edu.wpi.first.math.proto.Plant.ProtobufDCMotor;
+import edu.wpi.first.math.system.plant.DCMotor;
+import edu.wpi.first.util.protobuf.Protobuf;
+import us.hebi.quickbuf.Descriptors.Descriptor;
+
+public class DCMotorProto implements Protobuf<DCMotor, ProtobufDCMotor> {
+  @Override
+  public Class<DCMotor> getTypeClass() {
+    return DCMotor.class;
+  }
+
+  @Override
+  public Descriptor getDescriptor() {
+    return ProtobufDCMotor.getDescriptor();
+  }
+
+  @Override
+  public ProtobufDCMotor createMessage() {
+    return ProtobufDCMotor.newInstance();
+  }
+
+  @Override
+  public DCMotor unpack(ProtobufDCMotor msg) {
+    return new DCMotor(
+        msg.getNominalVoltage(),
+        msg.getStallTorque(),
+        msg.getStallCurrent(),
+        msg.getFreeCurrent(),
+        msg.getFreeSpeed(),
+        1);
+  }
+
+  @Override
+  public void pack(ProtobufDCMotor msg, DCMotor value) {
+    msg.setNominalVoltage(value.nominalVoltageVolts);
+    msg.setStallTorque(value.stallTorqueNewtonMeters);
+    msg.setStallCurrent(value.stallCurrentAmps);
+    msg.setFreeCurrent(value.freeCurrentAmps);
+    msg.setFreeSpeed(value.freeSpeedRadPerSec);
+  }
+}

wpimath/src/main/java/edu/wpi/first/math/system/plant/struct/DCMotorStruct.java

@@ -0,0 +1,51 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.math.system.plant.struct;
+
+import edu.wpi.first.math.system.plant.DCMotor;
+import edu.wpi.first.util.struct.Struct;
+import java.nio.ByteBuffer;
+
+public class DCMotorStruct implements Struct<DCMotor> {
+  @Override
+  public Class<DCMotor> getTypeClass() {
+    return DCMotor.class;
+  }
+
+  @Override
+  public String getTypeString() {
+    return "struct:DCMotor";
+  }
+
+  @Override
+  public int getSize() {
+    return kSizeDouble * 5;
+  }
+
+  @Override
+  public String getSchema() {
+    return "double nominal_voltage;double stall_torque;double stall_current;"
+        + "double free_current;double free_speed";
+  }
+
+  @Override
+  public DCMotor unpack(ByteBuffer bb) {
+    double nominalVoltage = bb.getDouble();
+    double stallTorque = bb.getDouble();
+    double stallCurrent = bb.getDouble();
+    double freeCurrent = bb.getDouble();
+    double freeSpeed = bb.getDouble();
+    return new DCMotor(nominalVoltage, stallTorque, stallCurrent, freeCurrent, freeSpeed, 1);
+  }
+
+  @Override
+  public void pack(ByteBuffer bb, DCMotor value) {
+    bb.putDouble(value.nominalVoltageVolts);
+    bb.putDouble(value.stallTorqueNewtonMeters);
+    bb.putDouble(value.stallCurrentAmps);
+    bb.putDouble(value.freeCurrentAmps);
+    bb.putDouble(value.freeSpeedRadPerSec);
+  }
+}