diff --git a/hal/CMakeLists.txt b/hal/CMakeLists.txt
index e743c0fca5..569eed447d 100644
--- a/hal/CMakeLists.txt
+++ b/hal/CMakeLists.txt
@@ -37,7 +37,7 @@ set_target_properties(hal PROPERTIES DEBUG_POSTFIX "d")
 if(USE_EXTERNAL_HAL)
     include(${EXTERNAL_HAL_FILE})
 else()
-    target_sources(hal PRIVATE ${hal_sim_native_src} ${hal_sim_jni_src})
+    target_sources(hal PRIVATE ${hal_sim_native_src})
 endif()
 
 configure_file(src/generate/FRCUsageReporting.h.in gen/hal/FRCUsageReporting.h)
@@ -78,9 +78,7 @@ if (NOT WITHOUT_JAVA)
 
     configure_file(src/generate/FRCNetComm.java.in FRCNetComm.java)
 
-    file(GLOB
-        hal_shared_jni_src src/main/native/cpp/jni/*.cpp
-        hal_sim_jni_src src/main/native/sim/jni/*.cpp)
+    file(GLOB_RECURSE hal_shared_jni_src src/main/native/cpp/jni/*.cpp)
 
     file(GLOB_RECURSE JAVA_SOURCES
         ${CMAKE_CURRENT_BINARY_DIR}/FRCNetComm.java
@@ -103,8 +101,6 @@ if (NOT WITHOUT_JAVA)
 
     if(USE_EXTERNAL_HAL)
         include(${EXTERNAL_HAL_FILE})
-    else()
-        target_sources(haljni PRIVATE ${hal_sim_jni_src})
     endif()
 
     set_target_properties(haljni PROPERTIES OUTPUT_NAME "wpiHaljni")
diff --git a/hal/build.gradle b/hal/build.gradle
index 75ee2a8197..e5b5f6cdc1 100644
--- a/hal/build.gradle
+++ b/hal/build.gradle
@@ -69,33 +69,6 @@ ext {
         it.tasks.withType(AbstractNativeSourceCompileTask) {
             it.dependsOn generateUsageReporting
         }
-        if (it.targetPlatform.name == nativeUtils.wpi.platforms.roborio) {
-            it.sources {
-                athenaJniCpp(CppSourceSet) {
-                    source {
-                        srcDirs = ["${rootDir}/shared/singlelib", "$buildDir/generated/cpp"]
-                        include '**/*.cpp'
-                    }
-                    exportedHeaders {
-                        srcDir 'src/main/native/include'
-                        srcDir generatedHeaders
-                    }
-                }
-            }
-        } else {
-            it.sources {
-                simJniCpp(CppSourceSet) {
-                    source {
-                        srcDirs 'src/main/native/sim'
-                        include '**/jni/*.cpp'
-                    }
-                    exportedHeaders {
-                        srcDir 'src/main/native/include'
-                        srcDir generatedHeaders
-                    }
-                }
-            }
-        }
     }
     splitSetup = {
         it.tasks.withType(AbstractNativeSourceCompileTask) {
@@ -107,7 +80,6 @@ ext {
                     source {
                         srcDirs = ['src/main/native/athena']
                         include '**/*.cpp'
-                        exclude '**/jni/*.cpp'
                     }
                     exportedHeaders {
                         srcDir 'src/main/native/include'
@@ -121,7 +93,6 @@ ext {
                     source {
                         srcDirs 'src/main/native/sim'
                         include '**/*.cpp'
-                        exclude '**/jni/*.cpp'
                     }
                     exportedHeaders {
                         srcDir 'src/main/native/include'
@@ -134,7 +105,6 @@ ext {
 }
 
 apply from: "${rootDir}/shared/jni/setupBuild.gradle"
-apply from: 'simjni.gradle'
 
 sourceSets.main.java.srcDir "${buildDir}/generated/java/"
 
@@ -150,12 +120,6 @@ cppSourcesZip {
     from('src/main/native/sim') {
         into '/sim'
     }
-
-    from("$buildDir/generated/cpp") {
-        into '/athena/jni'
-    }
-
-    dependsOn generateAthenaSimFiles
 }
 
 cppHeadersZip {
diff --git a/hal/simjni.gradle b/hal/simjni.gradle
deleted file mode 100644
index d2ba22b993..0000000000
--- a/hal/simjni.gradle
+++ /dev/null
@@ -1,113 +0,0 @@
-def athenaSimJniOutputDir = file("$buildDir/generated/cpp")
-def athenaSimJniOutputFile = file("$athenaSimJniOutputDir/simjni.cpp")
-
-task generateAthenaSimFiles() {
-    Set dirs = [];
-
-    def createdTask = it
-    outputs.file athenaSimJniOutputFile
-
-    model {
-        components {
-            it.all { component ->
-                if (component in getJniSpecClass()) {
-                    component.binaries.all { binary ->
-                        if (binary.targetPlatform.name == nativeUtils.wpi.platforms.roborio) {
-                            binary.tasks.withType(CppCompile) {
-                                it.dependsOn createdTask
-                            }
-                            component.jniHeaderLocations.each {
-                                dependsOn it.key
-                                createdTask.inputs.dir it.value
-                                dirs << it.value
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    doLast {
-        def symbolList = []
-        dirs.each {
-            def tree = fileTree(dir: it)
-            tree.each { file ->
-                if (!file.name.contains('edu_wpi_first_hal_simulation_')) {
-                    return
-                }
-                boolean reading = false
-                String currentLine = ''
-                file.eachLine { line ->
-                    if (line.trim()) {
-                        if (line.contains(';') && reading) {
-                            currentLine += line.trim()
-                            reading = false
-                            symbolList << currentLine
-                            currentLine = ''
-                        }
-                        if (line.startsWith("JNIEXPORT ") && line.contains('JNICALL')) {
-                            if (line.contains(';')) {
-                                symbolList << line
-                                currentLine = ''
-                                reading = false
-                            } else {
-                                reading = true
-                                currentLine += line.trim()
-                            }
-
-                        }
-                    }
-                }
-            }
-        }
-        athenaSimJniOutputDir.mkdirs()
-        athenaSimJniOutputFile.withWriter { out ->
-            out.println '#include <jni.h>'
-            out.println '''
-static JavaVM* jvm = nullptr;
-
-namespace hal {
-namespace sim {
-jint SimOnLoad(JavaVM* vm, void* reserved) {
-  jvm = vm;
-
-  JNIEnv *env;
-  if (vm->GetEnv(reinterpret_cast<void **>(&env), JNI_VERSION_1_6) != JNI_OK)
-    return JNI_ERR;
-
-  return JNI_VERSION_1_6;
-}
-
-void SimOnUnload(JavaVM * vm, void* reserved) {
-  JNIEnv *env;
-  if (vm->GetEnv(reinterpret_cast<void **>(&env), JNI_VERSION_1_6) != JNI_OK)
-    return;
-  jvm = nullptr;
-}
-}
-}
-
-static void ThrowSimException(JNIEnv* env) {
-
-}
-'''
-            out.println 'extern "C" {'
-            symbolList.each {
-                def symbol = it.replace('JNIEnv *', 'JNIEnv * env')
-                if (symbol.contains('JNIEXPORT void')) {
-                    symbol = symbol.replace(';', ''' {
-  ThrowSimException(env);
-}''')
-                } else {
-                    symbol = symbol.replace(';', ''' {
-  ThrowSimException(env);
-  return 0;
-}''')
-                }
-                out.println symbol
-            }
-            out.println '}'
-        }
-    }
-}
diff --git a/hal/src/main/native/athena/mockdata/AccelerometerData.cpp b/hal/src/main/native/athena/mockdata/AccelerometerData.cpp
new file mode 100644
index 0000000000..2baaf78e4e
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/AccelerometerData.cpp
@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/AccelerometerData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetAccelerometerData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, Accelerometer##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Active, false)
+DEFINE_CAPI(HAL_AccelerometerRange, Range, HAL_AccelerometerRange_k2G)
+DEFINE_CAPI(double, X, 0)
+DEFINE_CAPI(double, Y, 0)
+DEFINE_CAPI(double, Z, 0)
+
+void HALSIM_RegisterAccelerometerAllCallbacks(int32_t index,
+                                              HAL_NotifyCallback callback,
+                                              void* param,
+                                              HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/AddressableLEDData.cpp b/hal/src/main/native/athena/mockdata/AddressableLEDData.cpp
new file mode 100644
index 0000000000..d7187892dd
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/AddressableLEDData.cpp
@@ -0,0 +1,45 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/AddressableLEDData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+
+int32_t HALSIM_FindAddressableLEDForChannel(int32_t channel) { return 0; }
+
+void HALSIM_ResetAddressableLEDData(int32_t index) {}
+
+int32_t HALSIM_GetAddressableLEDData(int32_t index,
+                                     struct HAL_AddressableLEDData* data) {
+  return 0;
+}
+
+void HALSIM_SetAddressableLEDData(int32_t index,
+                                  const struct HAL_AddressableLEDData* data,
+                                  int32_t length) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, AddressableLED##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(int32_t, OutputPort, 0)
+DEFINE_CAPI(int32_t, Length, 0)
+DEFINE_CAPI(HAL_Bool, Running, false)
+
+#undef DEFINE_CAPI
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMCALLBACKREGISTRY_STUB_CAPI(TYPE, HALSIM, AddressableLED##CAPINAME)
+
+DEFINE_CAPI(HAL_ConstBufferCallback, Data, data)
+
+void HALSIM_RegisterAddressableLEDAllCallbacks(int32_t index,
+                                               HAL_NotifyCallback callback,
+                                               void* param,
+                                               HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/AnalogGyroData.cpp b/hal/src/main/native/athena/mockdata/AnalogGyroData.cpp
new file mode 100644
index 0000000000..d91ce27462
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/AnalogGyroData.cpp
@@ -0,0 +1,26 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/AnalogGyroData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetAnalogGyroData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, AnalogGyro##CAPINAME, RETURN)
+
+DEFINE_CAPI(double, Angle, 0)
+DEFINE_CAPI(double, Rate, 0)
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+
+void HALSIM_RegisterAnalogGyroAllCallbacks(int32_t index,
+                                           HAL_NotifyCallback callback,
+                                           void* param,
+                                           HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/AnalogInData.cpp b/hal/src/main/native/athena/mockdata/AnalogInData.cpp
new file mode 100644
index 0000000000..428853896d
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/AnalogInData.cpp
@@ -0,0 +1,33 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/AnalogInData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetAnalogInData(int32_t index) {}
+
+HAL_SimDeviceHandle HALSIM_GetAnalogInSimDevice(int32_t index) { return 0; }
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, AnalogIn##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(int32_t, AverageBits, 0)
+DEFINE_CAPI(int32_t, OversampleBits, 0)
+DEFINE_CAPI(double, Voltage, 0)
+DEFINE_CAPI(HAL_Bool, AccumulatorInitialized, false)
+DEFINE_CAPI(int64_t, AccumulatorValue, 0)
+DEFINE_CAPI(int64_t, AccumulatorCount, 0)
+DEFINE_CAPI(int32_t, AccumulatorCenter, 0)
+DEFINE_CAPI(int32_t, AccumulatorDeadband, 0)
+
+void HALSIM_RegisterAnalogInAllCallbacks(int32_t index,
+                                         HAL_NotifyCallback callback,
+                                         void* param, HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/AnalogOutData.cpp b/hal/src/main/native/athena/mockdata/AnalogOutData.cpp
new file mode 100644
index 0000000000..f05b0be3e1
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/AnalogOutData.cpp
@@ -0,0 +1,25 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/AnalogOutData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetAnalogOutData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, AnalogOut##CAPINAME, RETURN)
+
+DEFINE_CAPI(double, Voltage, 0)
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+
+void HALSIM_RegisterAnalogOutAllCallbacks(int32_t index,
+                                          HAL_NotifyCallback callback,
+                                          void* param, HAL_Bool initialNotify) {
+}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/AnalogTriggerData.cpp b/hal/src/main/native/athena/mockdata/AnalogTriggerData.cpp
new file mode 100644
index 0000000000..7781cf2c73
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/AnalogTriggerData.cpp
@@ -0,0 +1,31 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/AnalogTriggerData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+
+int32_t HALSIM_FindAnalogTriggerForChannel(int32_t channel) { return 0; }
+
+void HALSIM_ResetAnalogTriggerData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, AnalogTrigger##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(double, TriggerLowerBound, 0)
+DEFINE_CAPI(double, TriggerUpperBound, 0)
+DEFINE_CAPI(HALSIM_AnalogTriggerMode, TriggerMode,
+            HALSIM_AnalogTriggerUnassigned)
+
+void HALSIM_RegisterAnalogTriggerAllCallbacks(int32_t index,
+                                              HAL_NotifyCallback callback,
+                                              void* param,
+                                              HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/CanDataInternal.cpp b/hal/src/main/native/athena/mockdata/CanDataInternal.cpp
new file mode 100644
index 0000000000..69debf0cee
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/CanDataInternal.cpp
@@ -0,0 +1,25 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/CanData.h"
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+
+void HALSIM_ResetCanData(void) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME) \
+  HAL_SIMCALLBACKREGISTRY_STUB_CAPI_NOINDEX(TYPE, HALSIM, Can##CAPINAME)
+
+DEFINE_CAPI(HAL_CAN_SendMessageCallback, SendMessage)
+DEFINE_CAPI(HAL_CAN_ReceiveMessageCallback, ReceiveMessage)
+DEFINE_CAPI(HAL_CAN_OpenStreamSessionCallback, OpenStream)
+DEFINE_CAPI(HAL_CAN_CloseStreamSessionCallback, CloseStream)
+DEFINE_CAPI(HAL_CAN_ReadStreamSessionCallback, ReadStream)
+DEFINE_CAPI(HAL_CAN_GetCANStatusCallback, GetCANStatus)
+
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/DIOData.cpp b/hal/src/main/native/athena/mockdata/DIOData.cpp
new file mode 100644
index 0000000000..a06855d80c
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/DIOData.cpp
@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/DIOData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetDIOData(int32_t index) {}
+
+HAL_SimDeviceHandle HALSIM_GetDIOSimDevice(int32_t index) { return 0; }
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, DIO##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(HAL_Bool, Value, false)
+DEFINE_CAPI(double, PulseLength, 0)
+DEFINE_CAPI(HAL_Bool, IsInput, false)
+DEFINE_CAPI(int32_t, FilterIndex, 0)
+
+void HALSIM_RegisterDIOAllCallbacks(int32_t index, HAL_NotifyCallback callback,
+                                    void* param, HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/DigitalPWMData.cpp b/hal/src/main/native/athena/mockdata/DigitalPWMData.cpp
new file mode 100644
index 0000000000..bcbe370def
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/DigitalPWMData.cpp
@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/DigitalPWMData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+int32_t HALSIM_FindDigitalPWMForChannel(int32_t channel) { return 0; }
+
+void HALSIM_ResetDigitalPWMData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, DigitalPWM##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(double, DutyCycle, 0)
+DEFINE_CAPI(int32_t, Pin, 0)
+
+void HALSIM_RegisterDigitalPWMAllCallbacks(int32_t index,
+                                           HAL_NotifyCallback callback,
+                                           void* param,
+                                           HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/DriverStationData.cpp b/hal/src/main/native/athena/mockdata/DriverStationData.cpp
new file mode 100644
index 0000000000..744fc2b4a7
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/DriverStationData.cpp
@@ -0,0 +1,51 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/DriverStationData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetDriverStationData(void) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN)                                 \
+  HAL_SIMDATAVALUE_STUB_CAPI_NOINDEX(TYPE, HALSIM, DriverStation##CAPINAME, \
+                                     RETURN)
+
+DEFINE_CAPI(HAL_Bool, Enabled, false)
+DEFINE_CAPI(HAL_Bool, Autonomous, false)
+DEFINE_CAPI(HAL_Bool, Test, false)
+DEFINE_CAPI(HAL_Bool, EStop, false)
+DEFINE_CAPI(HAL_Bool, FmsAttached, false)
+DEFINE_CAPI(HAL_Bool, DsAttached, false)
+DEFINE_CAPI(HAL_AllianceStationID, AllianceStationId,
+            HAL_AllianceStationID_kRed1)
+DEFINE_CAPI(double, MatchTime, 0)
+
+void HALSIM_SetJoystickAxes(int32_t joystickNum, const HAL_JoystickAxes* axes) {
+}
+
+void HALSIM_SetJoystickPOVs(int32_t joystickNum, const HAL_JoystickPOVs* povs) {
+}
+
+void HALSIM_SetJoystickButtons(int32_t joystickNum,
+                               const HAL_JoystickButtons* buttons) {}
+
+void HALSIM_SetJoystickDescriptor(int32_t joystickNum,
+                                  const HAL_JoystickDescriptor* descriptor) {}
+
+void HALSIM_GetJoystickOutputs(int32_t joystickNum, int64_t* outputs,
+                               int32_t* leftRumble, int32_t* rightRumble) {}
+
+void HALSIM_SetMatchInfo(const HAL_MatchInfo* info) {}
+
+void HALSIM_NotifyDriverStationNewData(void) {}
+
+void HALSIM_RegisterDriverStationAllCallbacks(HAL_NotifyCallback callback,
+                                              void* param,
+                                              HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/DutyCycleData.cpp b/hal/src/main/native/athena/mockdata/DutyCycleData.cpp
new file mode 100644
index 0000000000..8d3cd617cf
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/DutyCycleData.cpp
@@ -0,0 +1,33 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/DutyCycleData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+int32_t HALSIM_FindDutyCycleForChannel(int32_t channel) { return 0; }
+
+void HALSIM_ResetDutyCycleData(int32_t index) {}
+
+int32_t HALSIM_GetDutyCycleDigitalChannel(int32_t index) { return 0; }
+
+HAL_SimDeviceHandle HALSIM_GetDutyCycleSimDevice(int32_t index) { return 0; }
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, DutyCycle##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(int32_t, Frequency, 0)
+DEFINE_CAPI(double, Output, 0)
+
+void HALSIM_RegisterDutyCycleAllCallbacks(int32_t index,
+                                          HAL_NotifyCallback callback,
+                                          void* param, HAL_Bool initialNotify) {
+}
+
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/EncoderData.cpp b/hal/src/main/native/athena/mockdata/EncoderData.cpp
new file mode 100644
index 0000000000..87a7385593
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/EncoderData.cpp
@@ -0,0 +1,47 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/EncoderData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+int32_t HALSIM_FindEncoderForChannel(int32_t channel) { return 0; }
+
+void HALSIM_ResetEncoderData(int32_t index) {}
+
+int32_t HALSIM_GetEncoderDigitalChannelA(int32_t index) { return 0; }
+
+int32_t HALSIM_GetEncoderDigitalChannelB(int32_t index) { return 0; }
+
+HAL_SimDeviceHandle HALSIM_GetEncoderSimDevice(int32_t index) { return 0; }
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, Encoder##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(int32_t, Count, 0)
+DEFINE_CAPI(double, Period, 0)
+DEFINE_CAPI(HAL_Bool, Reset, false)
+DEFINE_CAPI(double, MaxPeriod, 0)
+DEFINE_CAPI(HAL_Bool, Direction, false)
+DEFINE_CAPI(HAL_Bool, ReverseDirection, false)
+DEFINE_CAPI(int32_t, SamplesToAverage, 0)
+DEFINE_CAPI(double, DistancePerPulse, 0)
+
+void HALSIM_SetEncoderDistance(int32_t index, double distance) {}
+
+double HALSIM_GetEncoderDistance(int32_t index) { return 0; }
+
+void HALSIM_SetEncoderRate(int32_t index, double rate) {}
+
+double HALSIM_GetEncoderRate(int32_t index) { return 0; }
+
+void HALSIM_RegisterEncoderAllCallbacks(int32_t index,
+                                        HAL_NotifyCallback callback,
+                                        void* param, HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/I2CData.cpp b/hal/src/main/native/athena/mockdata/I2CData.cpp
new file mode 100644
index 0000000000..eb6a6c901c
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/I2CData.cpp
@@ -0,0 +1,27 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/I2CData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetI2CData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, I2C##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+
+#undef DEFINE_CAPI
+#define DEFINE_CAPI(TYPE, CAPINAME) \
+  HAL_SIMCALLBACKREGISTRY_STUB_CAPI(TYPE, HALSIM, I2C##CAPINAME)
+
+DEFINE_CAPI(HAL_BufferCallback, Read)
+DEFINE_CAPI(HAL_ConstBufferCallback, Write)
+
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/MockHooks.cpp b/hal/src/main/native/athena/mockdata/MockHooks.cpp
new file mode 100644
index 0000000000..3302d740d8
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/MockHooks.cpp
@@ -0,0 +1,34 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/MockHooks.h"
+
+extern "C" {
+
+void HALSIM_SetRuntimeType(HAL_RuntimeType type) {}
+
+void HALSIM_WaitForProgramStart(void) {}
+
+void HALSIM_SetProgramStarted(void) {}
+
+HAL_Bool HALSIM_GetProgramStarted(void) { return false; }
+
+void HALSIM_RestartTiming(void) {}
+
+void HALSIM_PauseTiming(void) {}
+
+void HALSIM_ResumeTiming(void) {}
+
+HAL_Bool HALSIM_IsTimingPaused(void) { return false; }
+
+void HALSIM_StepTiming(uint64_t delta) {}
+
+void HALSIM_SetSendError(HALSIM_SendErrorHandler handler) {}
+
+void HALSIM_SetSendConsoleLine(HALSIM_SendConsoleLineHandler handler) {}
+
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/NotifierData.cpp b/hal/src/main/native/athena/mockdata/NotifierData.cpp
new file mode 100644
index 0000000000..34aa6e7669
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/NotifierData.cpp
@@ -0,0 +1,20 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2016-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/NotifierData.h"
+
+extern "C" {
+
+uint64_t HALSIM_GetNextNotifierTimeout(void) { return 0; }
+
+int32_t HALSIM_GetNumNotifiers(void) { return 0; }
+
+int32_t HALSIM_GetNotifierInfo(struct HALSIM_NotifierInfo* arr, int32_t size) {
+  return 0;
+}
+
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/PCMData.cpp b/hal/src/main/native/athena/mockdata/PCMData.cpp
new file mode 100644
index 0000000000..29302cb714
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/PCMData.cpp
@@ -0,0 +1,40 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/PCMData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetPCMData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, PCM##CAPINAME, RETURN)
+
+HAL_SIMDATAVALUE_STUB_CAPI_CHANNEL(HAL_Bool, HALSIM, PCMSolenoidInitialized,
+                                   false)
+HAL_SIMDATAVALUE_STUB_CAPI_CHANNEL(HAL_Bool, HALSIM, PCMSolenoidOutput, false)
+DEFINE_CAPI(HAL_Bool, CompressorInitialized, false)
+DEFINE_CAPI(HAL_Bool, CompressorOn, false)
+DEFINE_CAPI(HAL_Bool, ClosedLoopEnabled, false)
+DEFINE_CAPI(HAL_Bool, PressureSwitch, false)
+DEFINE_CAPI(double, CompressorCurrent, 0)
+
+void HALSIM_GetPCMAllSolenoids(int32_t index, uint8_t* values) { *values = 0; }
+
+void HALSIM_SetPCMAllSolenoids(int32_t index, uint8_t values) {}
+
+void HALSIM_RegisterPCMAllNonSolenoidCallbacks(int32_t index,
+                                               HAL_NotifyCallback callback,
+                                               void* param,
+                                               HAL_Bool initialNotify) {}
+
+void HALSIM_RegisterPCMAllSolenoidCallbacks(int32_t index, int32_t channel,
+                                            HAL_NotifyCallback callback,
+                                            void* param,
+                                            HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/PDPData.cpp b/hal/src/main/native/athena/mockdata/PDPData.cpp
new file mode 100644
index 0000000000..a28bb817a4
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/PDPData.cpp
@@ -0,0 +1,34 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/PDPData.h"
+
+#include "../PortsInternal.h"
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetPDPData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, PDP##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(double, Temperature, 0)
+DEFINE_CAPI(double, Voltage, 0)
+HAL_SIMDATAVALUE_STUB_CAPI_CHANNEL(double, HALSIM, PDPCurrent, 0)
+
+void HALSIM_GetPDPAllCurrents(int32_t index, double* currents) {
+  for (int i = 0; i < hal::kNumPDPChannels; i++) currents[i] = 0;
+}
+
+void HALSIM_SetPDPAllCurrents(int32_t index, const double* currents) {}
+
+void HALSIM_RegisterPDPAllNonCurrentCallbacks(int32_t index, int32_t channel,
+                                              HAL_NotifyCallback callback,
+                                              void* param,
+                                              HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/PWMData.cpp b/hal/src/main/native/athena/mockdata/PWMData.cpp
new file mode 100644
index 0000000000..b9c5691115
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/PWMData.cpp
@@ -0,0 +1,27 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/PWMData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetPWMData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, PWM##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+DEFINE_CAPI(int32_t, RawValue, 0)
+DEFINE_CAPI(double, Speed, 0)
+DEFINE_CAPI(double, Position, 0)
+DEFINE_CAPI(int32_t, PeriodScale, 0)
+DEFINE_CAPI(HAL_Bool, ZeroLatch, false)
+
+void HALSIM_RegisterPWMAllCallbacks(int32_t index, HAL_NotifyCallback callback,
+                                    void* param, HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/RelayData.cpp b/hal/src/main/native/athena/mockdata/RelayData.cpp
new file mode 100644
index 0000000000..734bf89604
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/RelayData.cpp
@@ -0,0 +1,26 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/RelayData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetRelayData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, Relay##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, InitializedForward, false)
+DEFINE_CAPI(HAL_Bool, InitializedReverse, false)
+DEFINE_CAPI(HAL_Bool, Forward, false)
+DEFINE_CAPI(HAL_Bool, Reverse, false)
+
+void HALSIM_RegisterRelayAllCallbacks(int32_t index,
+                                      HAL_NotifyCallback callback, void* param,
+                                      HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/RoboRioData.cpp b/hal/src/main/native/athena/mockdata/RoboRioData.cpp
new file mode 100644
index 0000000000..f9e9ca7f1d
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/RoboRioData.cpp
@@ -0,0 +1,36 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/RoboRioData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetRoboRioData(void) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI_NOINDEX(TYPE, HALSIM, RoboRio##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, FPGAButton, false)
+DEFINE_CAPI(double, VInVoltage, 0)
+DEFINE_CAPI(double, VInCurrent, 0)
+DEFINE_CAPI(double, UserVoltage6V, 0)
+DEFINE_CAPI(double, UserCurrent6V, 0)
+DEFINE_CAPI(HAL_Bool, UserActive6V, false)
+DEFINE_CAPI(double, UserVoltage5V, 0)
+DEFINE_CAPI(double, UserCurrent5V, 0)
+DEFINE_CAPI(HAL_Bool, UserActive5V, false)
+DEFINE_CAPI(double, UserVoltage3V3, 0)
+DEFINE_CAPI(double, UserCurrent3V3, 0)
+DEFINE_CAPI(HAL_Bool, UserActive3V3, false)
+DEFINE_CAPI(int32_t, UserFaults6V, 0)
+DEFINE_CAPI(int32_t, UserFaults5V, 0)
+DEFINE_CAPI(int32_t, UserFaults3V3, 0)
+
+void HALSIM_RegisterRoboRioAllCallbacks(HAL_NotifyCallback callback,
+                                        void* param, HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/SPIAccelerometerData.cpp b/hal/src/main/native/athena/mockdata/SPIAccelerometerData.cpp
new file mode 100644
index 0000000000..c3e8ede784
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/SPIAccelerometerData.cpp
@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/SPIAccelerometerData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetSPIAccelerometerData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, SPIAccelerometer##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Active, false)
+DEFINE_CAPI(int32_t, Range, 0)
+DEFINE_CAPI(double, X, 0)
+DEFINE_CAPI(double, Y, 0)
+DEFINE_CAPI(double, Z, 0)
+
+void HALSIM_RegisterSPIAccelerometerAllCallbcaks(int32_t index,
+                                                 HAL_NotifyCallback callback,
+                                                 void* param,
+                                                 HAL_Bool initialNotify) {}
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/SPIData.cpp b/hal/src/main/native/athena/mockdata/SPIData.cpp
new file mode 100644
index 0000000000..13cf67c95f
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/SPIData.cpp
@@ -0,0 +1,28 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/SPIData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+void HALSIM_ResetSPIData(int32_t index) {}
+
+#define DEFINE_CAPI(TYPE, CAPINAME, RETURN) \
+  HAL_SIMDATAVALUE_STUB_CAPI(TYPE, HALSIM, SPI##CAPINAME, RETURN)
+
+DEFINE_CAPI(HAL_Bool, Initialized, false)
+
+#undef DEFINE_CAPI
+#define DEFINE_CAPI(TYPE, CAPINAME) \
+  HAL_SIMCALLBACKREGISTRY_STUB_CAPI(TYPE, HALSIM, SPI##CAPINAME)
+
+DEFINE_CAPI(HAL_BufferCallback, Read)
+DEFINE_CAPI(HAL_ConstBufferCallback, Write)
+DEFINE_CAPI(HAL_SpiReadAutoReceiveBufferCallback, ReadAutoReceivedData)
+
+}  // extern "C"
diff --git a/hal/src/main/native/athena/mockdata/SimDeviceData.cpp b/hal/src/main/native/athena/mockdata/SimDeviceData.cpp
new file mode 100644
index 0000000000..a31160c85d
--- /dev/null
+++ b/hal/src/main/native/athena/mockdata/SimDeviceData.cpp
@@ -0,0 +1,78 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019-2020 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "hal/simulation/SimDeviceData.h"
+
+#include "hal/simulation/SimDataValue.h"
+
+extern "C" {
+
+void HALSIM_SetSimDeviceEnabled(const char* prefix, HAL_Bool enabled) {}
+
+HAL_Bool HALSIM_IsSimDeviceEnabled(const char* name) { return false; }
+
+int32_t HALSIM_RegisterSimDeviceCreatedCallback(
+    const char* prefix, void* param, HALSIM_SimDeviceCallback callback,
+    HAL_Bool initialNotify) {
+  return 0;
+}
+
+void HALSIM_CancelSimDeviceCreatedCallback(int32_t uid) {}
+
+int32_t HALSIM_RegisterSimDeviceFreedCallback(
+    const char* prefix, void* param, HALSIM_SimDeviceCallback callback) {
+  return 0;
+}
+
+void HALSIM_CancelSimDeviceFreedCallback(int32_t uid) {}
+
+HAL_SimDeviceHandle HALSIM_GetSimDeviceHandle(const char* name) { return 0; }
+
+const char* HALSIM_GetSimDeviceName(HAL_SimDeviceHandle handle) { return ""; }
+
+HAL_SimDeviceHandle HALSIM_GetSimValueDeviceHandle(HAL_SimValueHandle handle) {
+  return 0;
+}
+
+void HALSIM_EnumerateSimDevices(const char* prefix, void* param,
+                                HALSIM_SimDeviceCallback callback) {}
+
+int32_t HALSIM_RegisterSimValueCreatedCallback(HAL_SimDeviceHandle device,
+                                               void* param,
+                                               HALSIM_SimValueCallback callback,
+                                               HAL_Bool initialNotify) {
+  return 0;
+}
+
+void HALSIM_CancelSimValueCreatedCallback(int32_t uid) {}
+
+int32_t HALSIM_RegisterSimValueChangedCallback(HAL_SimValueHandle handle,
+                                               void* param,
+                                               HALSIM_SimValueCallback callback,
+                                               HAL_Bool initialNotify) {
+  return 0;
+}
+
+void HALSIM_CancelSimValueChangedCallback(int32_t uid) {}
+
+HAL_SimValueHandle HALSIM_GetSimValueHandle(HAL_SimDeviceHandle device,
+                                            const char* name) {
+  return 0;
+}
+
+void HALSIM_EnumerateSimValues(HAL_SimDeviceHandle device, void* param,
+                               HALSIM_SimValueCallback callback) {}
+
+const char** HALSIM_GetSimValueEnumOptions(HAL_SimValueHandle handle,
+                                           int32_t* numOptions) {
+  *numOptions = 0;
+  return nullptr;
+}
+
+void HALSIM_ResetSimDeviceData(void) {}
+
+}  // extern "C"
diff --git a/hal/src/main/native/sim/jni/AccelerometerDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AccelerometerDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/AccelerometerDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/AccelerometerDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/AddressableLEDDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AddressableLEDDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/AddressableLEDDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/AddressableLEDDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/AnalogGyroDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AnalogGyroDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/AnalogGyroDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/AnalogGyroDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/AnalogInDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AnalogInDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/AnalogInDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/AnalogInDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/AnalogOutDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AnalogOutDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/AnalogOutDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/AnalogOutDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/AnalogTriggerDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AnalogTriggerDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/AnalogTriggerDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/AnalogTriggerDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/BufferCallbackStore.cpp b/hal/src/main/native/cpp/jni/simulation/BufferCallbackStore.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/BufferCallbackStore.cpp
rename to hal/src/main/native/cpp/jni/simulation/BufferCallbackStore.cpp
diff --git a/hal/src/main/native/sim/jni/BufferCallbackStore.h b/hal/src/main/native/cpp/jni/simulation/BufferCallbackStore.h
similarity index 100%
rename from hal/src/main/native/sim/jni/BufferCallbackStore.h
rename to hal/src/main/native/cpp/jni/simulation/BufferCallbackStore.h
diff --git a/hal/src/main/native/sim/jni/CallbackStore.cpp b/hal/src/main/native/cpp/jni/simulation/CallbackStore.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/CallbackStore.cpp
rename to hal/src/main/native/cpp/jni/simulation/CallbackStore.cpp
diff --git a/hal/src/main/native/sim/jni/CallbackStore.h b/hal/src/main/native/cpp/jni/simulation/CallbackStore.h
similarity index 100%
rename from hal/src/main/native/sim/jni/CallbackStore.h
rename to hal/src/main/native/cpp/jni/simulation/CallbackStore.h
diff --git a/hal/src/main/native/sim/jni/ConstBufferCallbackStore.cpp b/hal/src/main/native/cpp/jni/simulation/ConstBufferCallbackStore.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/ConstBufferCallbackStore.cpp
rename to hal/src/main/native/cpp/jni/simulation/ConstBufferCallbackStore.cpp
diff --git a/hal/src/main/native/sim/jni/ConstBufferCallbackStore.h b/hal/src/main/native/cpp/jni/simulation/ConstBufferCallbackStore.h
similarity index 100%
rename from hal/src/main/native/sim/jni/ConstBufferCallbackStore.h
rename to hal/src/main/native/cpp/jni/simulation/ConstBufferCallbackStore.h
diff --git a/hal/src/main/native/sim/jni/DIODataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/DIODataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/DIODataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/DIODataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/DigitalPWMDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/DigitalPWMDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/DigitalPWMDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/DigitalPWMDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/DriverStationDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/DriverStationDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/DriverStationDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/DriverStationDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/DutyCycleDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/DutyCycleDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/DutyCycleDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/DutyCycleDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/EncoderDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/EncoderDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/EncoderDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/EncoderDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/I2CDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/I2CDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/I2CDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/I2CDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/NotifierDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/NotifierDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/NotifierDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/NotifierDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/PCMDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/PCMDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/PCMDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/PCMDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/PDPDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/PDPDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/PDPDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/PDPDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/PWMDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/PWMDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/PWMDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/PWMDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/RelayDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/RelayDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/RelayDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/RelayDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/RoboRioDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/RoboRioDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/RoboRioDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/RoboRioDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/SPIAccelerometerDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/SPIAccelerometerDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/SPIAccelerometerDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/SPIAccelerometerDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/SPIDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/SPIDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/SPIDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/SPIDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/SimDeviceDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/SimDeviceDataJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.cpp
diff --git a/hal/src/main/native/sim/jni/SimDeviceDataJNI.h b/hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.h
similarity index 100%
rename from hal/src/main/native/sim/jni/SimDeviceDataJNI.h
rename to hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.h
diff --git a/hal/src/main/native/sim/jni/SimulatorJNI.cpp b/hal/src/main/native/cpp/jni/simulation/SimulatorJNI.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/SimulatorJNI.cpp
rename to hal/src/main/native/cpp/jni/simulation/SimulatorJNI.cpp
diff --git a/hal/src/main/native/sim/jni/SimulatorJNI.h b/hal/src/main/native/cpp/jni/simulation/SimulatorJNI.h
similarity index 100%
rename from hal/src/main/native/sim/jni/SimulatorJNI.h
rename to hal/src/main/native/cpp/jni/simulation/SimulatorJNI.h
diff --git a/hal/src/main/native/sim/jni/SpiReadAutoReceiveBufferCallbackStore.cpp b/hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.cpp
similarity index 100%
rename from hal/src/main/native/sim/jni/SpiReadAutoReceiveBufferCallbackStore.cpp
rename to hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.cpp
diff --git a/hal/src/main/native/sim/jni/SpiReadAutoReceiveBufferCallbackStore.h b/hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.h
similarity index 100%
rename from hal/src/main/native/sim/jni/SpiReadAutoReceiveBufferCallbackStore.h
rename to hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.h
diff --git a/hal/src/main/native/include/hal/simulation/SimCallbackRegistry.h b/hal/src/main/native/include/hal/simulation/SimCallbackRegistry.h
index bedc81b2ab..bdd6f45611 100644
--- a/hal/src/main/native/include/hal/simulation/SimCallbackRegistry.h
+++ b/hal/src/main/native/include/hal/simulation/SimCallbackRegistry.h
@@ -152,4 +152,42 @@ class SimCallbackRegistry : public impl::SimCallbackRegistryBase {
     DATA->LOWERNAME.Cancel(uid);                                              \
   }
 
+/**
+ * Define a stub standard C API for SimCallbackRegistry.
+ *
+ * Functions defined:
+ * - int32 NS_RegisterCAPINAMECallback(
+ *      int32_t index, TYPE callback, void* param)
+ * - void NS_CancelCAPINAMECallback(int32_t index, int32_t uid)
+ *
+ * @param TYPE the underlying callback type (e.g. HAL_BufferCallback)
+ * @param NS the "namespace" (e.g. HALSIM)
+ * @param CAPINAME the C API name (usually first letter capitalized)
+ */
+#define HAL_SIMCALLBACKREGISTRY_STUB_CAPI(TYPE, NS, CAPINAME)             \
+  int32_t NS##_Register##CAPINAME##Callback(int32_t index, TYPE callback, \
+                                            void* param) {                \
+    return 0;                                                             \
+  }                                                                       \
+                                                                          \
+  void NS##_Cancel##CAPINAME##Callback(int32_t index, int32_t uid) {}
+
+/**
+ * Define a stub standard C API for SimCallbackRegistry (no index variant).
+ *
+ * Functions defined:
+ * - int32 NS_RegisterCAPINAMECallback(TYPE callback, void* param)
+ * - void NS_CancelCAPINAMECallback(int32_t uid)
+ *
+ * @param TYPE the underlying callback type (e.g. HAL_BufferCallback)
+ * @param NS the "namespace" (e.g. HALSIM)
+ * @param CAPINAME the C API name (usually first letter capitalized)
+ */
+#define HAL_SIMCALLBACKREGISTRY_STUB_CAPI_NOINDEX(TYPE, NS, CAPINAME)     \
+  int32_t NS##_Register##CAPINAME##Callback(TYPE callback, void* param) { \
+    return 0;                                                             \
+  }                                                                       \
+                                                                          \
+  void NS##_Cancel##CAPINAME##Callback(int32_t uid) {}
+
 }  // namespace hal
diff --git a/hal/src/main/native/include/hal/simulation/SimDataValue.h b/hal/src/main/native/include/hal/simulation/SimDataValue.h
index c06363acd2..360664e464 100644
--- a/hal/src/main/native/include/hal/simulation/SimDataValue.h
+++ b/hal/src/main/native/include/hal/simulation/SimDataValue.h
@@ -224,4 +224,90 @@ class SimDataValue final : public impl::SimDataValueBase<T, MakeValue> {
                                                                              \
   void NS##_Set##CAPINAME(TYPE LOWERNAME) { DATA->LOWERNAME = LOWERNAME; }
 
+/**
+ * Define a stub standard C API for simulation data.
+ *
+ * Functions defined:
+ * - int32 NS_RegisterCAPINAMECallback(
+ *      int32_t index, HAL_NotifyCallback callback, void* param,
+ *      HAL_Bool initialNotify)
+ * - void NS_CancelCAPINAMECallback(int32_t index, int32_t uid)
+ * - TYPE NS_GetCAPINAME(int32_t index)
+ * - void NS_SetCAPINAME(int32_t index, TYPE value)
+ *
+ * @param TYPE the underlying value type (e.g. double)
+ * @param NS the "namespace" (e.g. HALSIM)
+ * @param CAPINAME the C API name (usually first letter capitalized)
+ * @param RETURN what to return from the Get function
+ */
+#define HAL_SIMDATAVALUE_STUB_CAPI(TYPE, NS, CAPINAME, RETURN)        \
+  int32_t NS##_Register##CAPINAME##Callback(                          \
+      int32_t index, HAL_NotifyCallback callback, void* param,        \
+      HAL_Bool initialNotify) {                                       \
+    return 0;                                                         \
+  }                                                                   \
+                                                                      \
+  void NS##_Cancel##CAPINAME##Callback(int32_t index, int32_t uid) {} \
+                                                                      \
+  TYPE NS##_Get##CAPINAME(int32_t index) { return RETURN; }           \
+                                                                      \
+  void NS##_Set##CAPINAME(int32_t index, TYPE) {}
+
+/**
+ * Define a stub standard C API for simulation data (channel variant).
+ *
+ * Functions defined:
+ * - int32 NS_RegisterCAPINAMECallback(
+ *      int32_t index, int32_t channel, HAL_NotifyCallback callback,
+ *      void* param, HAL_Bool initialNotify)
+ * - void NS_CancelCAPINAMECallback(int32_t index, int32_t channel, int32_t uid)
+ * - TYPE NS_GetCAPINAME(int32_t index, int32_t channel)
+ * - void NS_SetCAPINAME(int32_t index, int32_t channel, TYPE value)
+ *
+ * @param TYPE the underlying value type (e.g. double)
+ * @param NS the "namespace" (e.g. HALSIM)
+ * @param CAPINAME the C API name (usually first letter capitalized)
+ * @param RETURN what to return from the Get function
+ */
+#define HAL_SIMDATAVALUE_STUB_CAPI_CHANNEL(TYPE, NS, CAPINAME, RETURN)       \
+  int32_t NS##_Register##CAPINAME##Callback(                                 \
+      int32_t index, int32_t channel, HAL_NotifyCallback callback,           \
+      void* param, HAL_Bool initialNotify) {                                 \
+    return 0;                                                                \
+  }                                                                          \
+                                                                             \
+  void NS##_Cancel##CAPINAME##Callback(int32_t index, int32_t channel,       \
+                                       int32_t uid) {}                       \
+                                                                             \
+  TYPE NS##_Get##CAPINAME(int32_t index, int32_t channel) { return RETURN; } \
+                                                                             \
+  void NS##_Set##CAPINAME(int32_t index, int32_t channel, TYPE) {}
+
+/**
+ * Define a stub standard C API for simulation data (no index variant).
+ *
+ * Functions defined:
+ * - int32 NS_RegisterCAPINAMECallback(
+ *      HAL_NotifyCallback callback, void* param, HAL_Bool initialNotify)
+ * - void NS_CancelCAPINAMECallback(int32_t uid)
+ * - TYPE NS_GetCAPINAME(void)
+ * - void NS_SetCAPINAME(TYPE value)
+ *
+ * @param TYPE the underlying value type (e.g. double)
+ * @param NS the "namespace" (e.g. HALSIM)
+ * @param CAPINAME the C API name (usually first letter capitalized)
+ * @param RETURN what to return from the Get function
+ */
+#define HAL_SIMDATAVALUE_STUB_CAPI_NOINDEX(TYPE, NS, CAPINAME, RETURN)    \
+  int32_t NS##_Register##CAPINAME##Callback(                              \
+      HAL_NotifyCallback callback, void* param, HAL_Bool initialNotify) { \
+    return 0;                                                             \
+  }                                                                       \
+                                                                          \
+  void NS##_Cancel##CAPINAME##Callback(int32_t uid) {}                    \
+                                                                          \
+  TYPE NS##_Get##CAPINAME(void) { return RETURN; }                        \
+                                                                          \
+  void NS##_Set##CAPINAME(TYPE) {}
+
 }  // namespace hal
diff --git a/shared/jni/setupBuild.gradle b/shared/jni/setupBuild.gradle
index 15805d2ba2..369422d4f3 100644
--- a/shared/jni/setupBuild.gradle
+++ b/shared/jni/setupBuild.gradle
@@ -43,7 +43,7 @@ model {
                     source {
                         srcDirs 'src/main/native/cpp'
                         include '**/*.cpp'
-                        exclude '**/jni/*.cpp'
+                        exclude '**/jni/**/*.cpp'
                     }
                     exportedHeaders {
                         srcDir 'src/main/native/include'
@@ -108,7 +108,7 @@ model {
                 cpp {
                     source {
                         srcDirs 'src/main/native/cpp'
-                        include '**/jni/*.cpp'
+                        include '**/jni/**/*.cpp'
                     }
                     exportedHeaders {
                         srcDir 'src/main/native/include'
@@ -150,7 +150,7 @@ model {
                 cpp {
                     source {
                         srcDirs 'src/main/native/cpp'
-                        include '**/jni/*.cpp'
+                        include '**/jni/**/*.cpp'
                     }
                     exportedHeaders {
                         srcDir 'src/main/native/include'