Better ringbuffer implementation.

src/xenia/base/ring_buffer.h

@@ -18,18 +18,39 @@ namespace xe {
 
 class RingBuffer {
   public:
-    RingBuffer(uint8_t *raw_buffer, size_t size, size_t write_offset = 0);
+    RingBuffer(uint8_t* raw_buffer, size_t size, size_t read_offset, size_t write_offset);
 
-    size_t Write(uint8_t *buffer, size_t num_bytes);
+    size_t Read(uint8_t* buffer, size_t num_bytes);
+    size_t Skip(size_t num_bytes);
+    size_t Write(uint8_t* buffer, size_t num_bytes);
 
-    size_t DistanceToOffset(size_t offset);
-
-    void set_write_offset(size_t write_offset) { write_offset_ = write_offset; }
+    size_t read_offset() { return read_offset_; }
     size_t write_offset() { return write_offset_; }
 
+    size_t read_size() {
+      if (read_offset_ == write_offset_) {
+        return 0;
+      }
+      if (read_offset_ < write_offset_) {
+        return write_offset_ - read_offset_;
+      }
+      return (size_ - read_offset_) + write_offset_;
+    }
+
+    size_t write_size() {
+      if (write_offset_ == read_offset_) {
+        return size_;
+      }
+      if (write_offset_ < read_offset_) {
+        return read_offset_ - write_offset_;
+      }
+      return (size_ - write_offset_) + read_offset_;
+    }
+
   private:
-    uint8_t *raw_buffer_;
+    uint8_t* raw_buffer_;
     size_t size_;
+    size_t read_offset_;
     size_t write_offset_;
 };