Initial Alloy implementation.

This is a regression in functionality and performance, but a much better
foundation for the future of the project (I think). It can run basic
apps under an SSA interpreter but doesn't support some of the features
required to do real 360 apps yet.

src/alloy/arena.cc

@@ -0,0 +1,92 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2013 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include <alloy/arena.h>
+
+using namespace alloy;
+
+
+Arena::Arena(size_t chunk_size) :
+    chunk_size_(chunk_size),
+    head_chunk_(NULL), active_chunk_(NULL) {
+}
+
+Arena::~Arena() {
+  Reset();
+  Chunk* chunk = head_chunk_;
+  while (chunk) {
+    Chunk* next = chunk->next;
+    delete chunk;
+    chunk = next;
+  }
+  head_chunk_ = NULL;
+}
+
+void Arena::Reset() {
+  active_chunk_ = head_chunk_;
+  if (active_chunk_) {
+    active_chunk_->offset = 0;
+  }
+}
+
+void* Arena::Alloc(size_t size) {
+  if (active_chunk_) {
+    if (active_chunk_->capacity - active_chunk_->offset < size) {
+      Chunk* next = active_chunk_->next;
+      if (!next) {
+        XEASSERT(size < size); // need to support larger chunks
+        next = new Chunk(chunk_size_);
+        active_chunk_->next = next;
+      }
+      active_chunk_ = next;
+    }
+  } else {
+    head_chunk_ = active_chunk_ = new Chunk(chunk_size_);
+  }
+
+  uint8_t* p = active_chunk_->buffer + active_chunk_->offset;
+  active_chunk_->offset += size;
+  return p;
+}
+
+void* Arena::CloneContents() {
+  size_t total_length = 0;
+  Chunk* chunk = head_chunk_;
+  while (chunk) {
+    total_length += chunk->offset;
+    if (chunk == active_chunk_) {
+      break;
+    }
+    chunk = chunk->next;
+  }
+  void* result = xe_malloc(total_length);
+  uint8_t* p = (uint8_t*)result;
+  chunk = head_chunk_;
+  while (chunk) {
+    xe_copy_struct(p, chunk->buffer, chunk->offset);
+    p += chunk->offset;
+    if (chunk == active_chunk_) {
+      break;
+    }
+    chunk = chunk->next;
+  }
+  return result;
+}
+
+Arena::Chunk::Chunk(size_t chunk_size) :
+    next(NULL),
+    capacity(chunk_size), buffer(0), offset(0) {
+  buffer = (uint8_t*)xe_malloc(capacity);
+}
+
+Arena::Chunk::~Chunk() {
+  if (buffer) {
+    xe_free(buffer);
+  }
+}