Move CFX_BitStream to its own file

This CL moves the CFX_BitStream code out of fx_basic and into
cfx_bitstream.

Bug: pdfium:867
Change-Id: I5b7e6190a7db1fe1d24feb6bd676035a5c73ee92
Reviewed-on: https://pdfium-review.googlesource.com/12350
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/core/fxcrt/cfx_bitstream.h b/core/fxcrt/cfx_bitstream.h
new file mode 100644
index 0000000000..1829f23b92
--- /dev/null
+++ b/core/fxcrt/cfx_bitstream.h
@@ -0,0 +1,38 @@
+// Copyright 2017 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#ifndef CORE_FXCRT_CFX_BITSTREAM_H_
+#define CORE_FXCRT_CFX_BITSTREAM_H_
+
+#include <stdint.h>
+
+#include "core/fxcrt/cfx_unowned_ptr.h"
+
+class CFX_BitStream {
+ public:
+  CFX_BitStream(const uint8_t* pData, uint32_t dwSize);
+  ~CFX_BitStream();
+
+  void ByteAlign();
+
+  bool IsEOF() const { return m_BitPos >= m_BitSize; }
+  uint32_t GetPos() const { return m_BitPos; }
+  uint32_t GetBits(uint32_t nBits);
+
+  void SkipBits(uint32_t nBits) { m_BitPos += nBits; }
+  void Rewind() { m_BitPos = 0; }
+
+  uint32_t BitsRemaining() const {
+    return m_BitSize >= m_BitPos ? m_BitSize - m_BitPos : 0;
+  }
+
+ private:
+  uint32_t m_BitPos;
+  uint32_t m_BitSize;
+  CFX_UnownedPtr<const uint8_t> m_pData;
+};
+
+#endif  // CORE_FXCRT_CFX_BITSTREAM_H_