Reland "Move webrtc/{base => rtc_base}" (https://codereview.webrtc.org/2877023002)
Reland the base->rtc_base without adding stub headers (will be
done in follow-up CL). This preserves git blame history of all files.
BUG=webrtc:7634
NOTRY=True
TBR=kwiberg@webrtc.org
Change-Id: Iea3bb6f3f67b8374c96337b63e8f5aa3e6181012
Reviewed-on: https://chromium-review.googlesource.com/554611
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18821}
diff --git a/webrtc/rtc_base/bitbuffer.h b/webrtc/rtc_base/bitbuffer.h
new file mode 100644
index 0000000..bd5e5f8
--- /dev/null
+++ b/webrtc/rtc_base/bitbuffer.h
@@ -0,0 +1,126 @@
+/*
+ * Copyright 2015 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_RTC_BASE_BITBUFFER_H_
+#define WEBRTC_RTC_BASE_BITBUFFER_H_
+
+#include <stdint.h> // For integer types.
+#include <stddef.h> // For size_t.
+
+#include "webrtc/base/constructormagic.h"
+
+namespace rtc {
+
+// A class, similar to ByteBuffer, that can parse bit-sized data out of a set of
+// bytes. Has a similar API to ByteBuffer, plus methods for reading bit-sized
+// and exponential golomb encoded data. For a writable version, use
+// BitBufferWriter. Unlike ByteBuffer, this class doesn't make a copy of the
+// source bytes, so it can be used on read-only data.
+// Sizes/counts specify bits/bytes, for clarity.
+// Byte order is assumed big-endian/network.
+class BitBuffer {
+ public:
+ BitBuffer(const uint8_t* bytes, size_t byte_count);
+
+ // Gets the current offset, in bytes/bits, from the start of the buffer. The
+ // bit offset is the offset into the current byte, in the range [0,7].
+ void GetCurrentOffset(size_t* out_byte_offset, size_t* out_bit_offset);
+
+ // The remaining bits in the byte buffer.
+ uint64_t RemainingBitCount() const;
+
+ // Reads byte-sized values from the buffer. Returns false if there isn't
+ // enough data left for the specified type.
+ bool ReadUInt8(uint8_t* val);
+ bool ReadUInt16(uint16_t* val);
+ bool ReadUInt32(uint32_t* val);
+
+ // Reads bit-sized values from the buffer. Returns false if there isn't enough
+ // data left for the specified bit count..
+ bool ReadBits(uint32_t* val, size_t bit_count);
+
+ // Peeks bit-sized values from the buffer. Returns false if there isn't enough
+ // data left for the specified number of bits. Doesn't move the current
+ // offset.
+ bool PeekBits(uint32_t* val, size_t bit_count);
+
+ // Reads the exponential golomb encoded value at the current offset.
+ // Exponential golomb values are encoded as:
+ // 1) x = source val + 1
+ // 2) In binary, write [countbits(x) - 1] 0s, then x
+ // To decode, we count the number of leading 0 bits, read that many + 1 bits,
+ // and increment the result by 1.
+ // Returns false if there isn't enough data left for the specified type, or if
+ // the value wouldn't fit in a uint32_t.
+ bool ReadExponentialGolomb(uint32_t* val);
+ // Reads signed exponential golomb values at the current offset. Signed
+ // exponential golomb values are just the unsigned values mapped to the
+ // sequence 0, 1, -1, 2, -2, etc. in order.
+ bool ReadSignedExponentialGolomb(int32_t* val);
+
+ // Moves current position |byte_count| bytes forward. Returns false if
+ // there aren't enough bytes left in the buffer.
+ bool ConsumeBytes(size_t byte_count);
+ // Moves current position |bit_count| bits forward. Returns false if
+ // there aren't enough bits left in the buffer.
+ bool ConsumeBits(size_t bit_count);
+
+ // Sets the current offset to the provied byte/bit offsets. The bit
+ // offset is from the given byte, in the range [0,7].
+ bool Seek(size_t byte_offset, size_t bit_offset);
+
+ protected:
+ const uint8_t* const bytes_;
+ // The total size of |bytes_|.
+ size_t byte_count_;
+ // The current offset, in bytes, from the start of |bytes_|.
+ size_t byte_offset_;
+ // The current offset, in bits, into the current byte.
+ size_t bit_offset_;
+
+ RTC_DISALLOW_COPY_AND_ASSIGN(BitBuffer);
+};
+
+// A BitBuffer API for write operations. Supports symmetric write APIs to the
+// reading APIs of BitBuffer. Note that the read/write offset is shared with the
+// BitBuffer API, so both reading and writing will consume bytes/bits.
+class BitBufferWriter : public BitBuffer {
+ public:
+ // Constructs a bit buffer for the writable buffer of |bytes|.
+ BitBufferWriter(uint8_t* bytes, size_t byte_count);
+
+ // Writes byte-sized values from the buffer. Returns false if there isn't
+ // enough data left for the specified type.
+ bool WriteUInt8(uint8_t val);
+ bool WriteUInt16(uint16_t val);
+ bool WriteUInt32(uint32_t val);
+
+ // Writes bit-sized values to the buffer. Returns false if there isn't enough
+ // room left for the specified number of bits.
+ bool WriteBits(uint64_t val, size_t bit_count);
+
+ // Writes the exponential golomb encoded version of the supplied value.
+ // Returns false if there isn't enough room left for the value.
+ bool WriteExponentialGolomb(uint32_t val);
+ // Writes the signed exponential golomb version of the supplied value.
+ // Signed exponential golomb values are just the unsigned values mapped to the
+ // sequence 0, 1, -1, 2, -2, etc. in order.
+ bool WriteSignedExponentialGolomb(int32_t val);
+
+ private:
+ // The buffer, as a writable array.
+ uint8_t* const writable_bytes_;
+
+ RTC_DISALLOW_COPY_AND_ASSIGN(BitBufferWriter);
+};
+
+} // namespace rtc
+
+#endif // WEBRTC_RTC_BASE_BITBUFFER_H_