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authorDan Sinclair <dsinclair@chromium.org>2017-08-30 13:23:44 -0400
committerChromium commit bot <commit-bot@chromium.org>2017-08-30 17:33:36 +0000
commitccd5be05f61c85754daf5c8155f4932f6d35a55a (patch)
tree7ec719348aed7e92cdb8b28887bffcf583a7c819 /core/fxcrt/cfx_bitstream.cpp
parent68eefa6a6f6bbab73000a29e2cac3e104be1cc81 (diff)
downloadpdfium-ccd5be05f61c85754daf5c8155f4932f6d35a55a.tar.xz
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>
Diffstat (limited to 'core/fxcrt/cfx_bitstream.cpp')
-rw-r--r--core/fxcrt/cfx_bitstream.cpp57
1 files changed, 57 insertions, 0 deletions
diff --git a/core/fxcrt/cfx_bitstream.cpp b/core/fxcrt/cfx_bitstream.cpp
new file mode 100644
index 0000000000..7cf6d36adf
--- /dev/null
+++ b/core/fxcrt/cfx_bitstream.cpp
@@ -0,0 +1,57 @@
+// 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
+
+#include "core/fxcrt/cfx_bitstream.h"
+
+#include <limits>
+
+#include "core/fxcrt/fx_system.h"
+
+CFX_BitStream::CFX_BitStream(const uint8_t* pData, uint32_t dwSize)
+ : m_BitPos(0), m_BitSize(dwSize * 8), m_pData(pData) {
+ ASSERT(dwSize <= std::numeric_limits<uint32_t>::max() / 8);
+}
+
+CFX_BitStream::~CFX_BitStream() {}
+
+void CFX_BitStream::ByteAlign() {
+ m_BitPos = (m_BitPos + 7) & ~7;
+}
+
+uint32_t CFX_BitStream::GetBits(uint32_t nBits) {
+ if (nBits > m_BitSize || m_BitPos + nBits > m_BitSize)
+ return 0;
+
+ const uint8_t* data = m_pData.Get();
+
+ if (nBits == 1) {
+ int bit = (data[m_BitPos / 8] & (1 << (7 - m_BitPos % 8))) ? 1 : 0;
+ m_BitPos++;
+ return bit;
+ }
+
+ uint32_t byte_pos = m_BitPos / 8;
+ uint32_t bit_pos = m_BitPos % 8;
+ uint32_t bit_left = nBits;
+ uint32_t result = 0;
+ if (bit_pos) {
+ if (8 - bit_pos >= bit_left) {
+ result = (data[byte_pos] & (0xff >> bit_pos)) >> (8 - bit_pos - bit_left);
+ m_BitPos += bit_left;
+ return result;
+ }
+ bit_left -= 8 - bit_pos;
+ result = (data[byte_pos++] & ((1 << (8 - bit_pos)) - 1)) << bit_left;
+ }
+ while (bit_left >= 8) {
+ bit_left -= 8;
+ result |= data[byte_pos++] << bit_left;
+ }
+ if (bit_left)
+ result |= data[byte_pos] >> (8 - bit_left);
+ m_BitPos += nBits;
+ return result;
+}