Renamed folders for consistency, using sim/athena/shared schema (#27)

Rename the following folders:
hal/lib/Athena -> hal/lib/athena
hal/lib/Desktop -> hal/lib/sim
hal/lib/Shared -> hal/lib/shared
wpilibc/Athena -> wpilibc/athena
wpilibc/simulation -> wpilibc/sim

Windows users may need to run gradlew clean after updating.

hal/lib/athena/cpp/Resource.cpp

@@ -0,0 +1,103 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2008-2016. 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/cpp/Resource.hpp"
+#include <cstddef>
+#include "HAL/Errors.hpp"
+#include "HAL/cpp/priority_mutex.h"
+
+namespace hal {
+
+priority_recursive_mutex Resource::m_createLock;
+
+/**
+ * Allocate storage for a new instance of Resource.
+ * Allocate a bool array of values that will get initialized to indicate that no
+ * resources have been allocated yet. The indicies of the resources are [0 ..
+ * elements - 1].
+ */
+Resource::Resource(uint32_t elements) {
+  std::lock_guard<priority_recursive_mutex> sync(m_createLock);
+  m_isAllocated = std::vector<bool>(elements, false);
+}
+
+/**
+ * Factory method to create a Resource allocation-tracker *if* needed.
+ *
+ * @param r -- address of the caller's Resource pointer. If *r == NULL, this
+ *    will construct a Resource and make *r point to it. If *r != NULL, i.e.
+ *    the caller already has a Resource instance, this won't do anything.
+ * @param elements -- the number of elements for this Resource allocator to
+ *    track, that is, it will allocate resource numbers in the range
+ *    [0 .. elements - 1].
+ */
+/*static*/ void Resource::CreateResourceObject(Resource** r,
+                                               uint32_t elements) {
+  std::lock_guard<priority_recursive_mutex> sync(m_createLock);
+  if (*r == NULL) {
+    *r = new Resource(elements);
+  }
+}
+
+/**
+ * Allocate a resource.
+ * When a resource is requested, mark it allocated. In this case, a free
+ * resource value
+ * within the range is located and returned after it is marked allocated.
+ */
+uint32_t Resource::Allocate(const char* resourceDesc) {
+  std::lock_guard<priority_recursive_mutex> sync(m_allocateLock);
+  for (uint32_t i = 0; i < m_isAllocated.size(); i++) {
+    if (!m_isAllocated[i]) {
+      m_isAllocated[i] = true;
+      return i;
+    }
+  }
+  // TODO: wpi_setWPIErrorWithContext(NoAvailableResources, resourceDesc);
+  return ~0ul;
+}
+
+/**
+ * Allocate a specific resource value.
+ * The user requests a specific resource value, i.e. channel number and it is
+ * verified unallocated, then returned.
+ */
+uint32_t Resource::Allocate(uint32_t index, const char* resourceDesc) {
+  std::lock_guard<priority_recursive_mutex> sync(m_allocateLock);
+  if (index >= m_isAllocated.size()) {
+    // TODO: wpi_setWPIErrorWithContext(ChannelIndexOutOfRange, resourceDesc);
+    return ~0ul;
+  }
+  if (m_isAllocated[index]) {
+    // TODO: wpi_setWPIErrorWithContext(ResourceAlreadyAllocated, resourceDesc);
+    return ~0ul;
+  }
+  m_isAllocated[index] = true;
+  return index;
+}
+
+/**
+ * Free an allocated resource.
+ * After a resource is no longer needed, for example a destructor is called for
+ * a channel assignment class, Free will release the resource value so it can
+ * be reused somewhere else in the program.
+ */
+void Resource::Free(uint32_t index) {
+  std::lock_guard<priority_recursive_mutex> sync(m_allocateLock);
+  if (index == ~0ul) return;
+  if (index >= m_isAllocated.size()) {
+    // TODO: wpi_setWPIError(NotAllocated);
+    return;
+  }
+  if (!m_isAllocated[index]) {
+    // TODO: wpi_setWPIError(NotAllocated);
+    return;
+  }
+  m_isAllocated[index] = false;
+}
+
+}  // namespace hal