215 lines
6.6 KiB
C++
215 lines
6.6 KiB
C++
/*
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Copyright (c) 2009-2010 Christopher A. Taylor. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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* Neither the name of LibCat nor the names of its contributors may be used
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to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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// Not currently being maintained.
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// FIXME: Big-endian code is untested
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// FIXME: Not suitable for storing large buffers > 500 MB in size
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#ifndef CAT_BIT_STREAM_HPP
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#define CAT_BIT_STREAM_HPP
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#include <cat/Platform.hpp>
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namespace cat {
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//// BitStream manipulators ////
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namespace bs_bit
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{
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template<u32 N_BITS> struct set
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{
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u32 bits;
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set(u32 c_bits) : bits(c_bits) { }
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};
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template<u32 N_BITS> struct get
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{
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u32 &ref;
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get(u32 &c_ref) : ref(c_ref) { }
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};
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}
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namespace bs_byte
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{
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struct set
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{
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u32 bytes;
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const void *ref;
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set(u32 b, const void *r) : ref(r), bytes(b) { }
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};
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struct get
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{
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u32 bytes;
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void *ref;
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get(u32 b, void *r) : ref(r), bytes(b) { }
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};
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}
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//// BitStream ////
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class BitStream
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{
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bool fixed_buffer;
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u8 *buffer;
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u32 buffer_bytes;
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bool read_underrun;
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// grow to be able to write a number of bits
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void grow(u32 bits);
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public:
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u32 read_offset, write_offset; // in bits
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public:
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BitStream(u32 bytes = 0, void *vbuffer = 0);
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~BitStream();
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// free unused buffer space
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void shrink();
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public:
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u8 *get() { return buffer; }
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bool aligned() { return read_offset % 8 == 0; }
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u8 *peek() { return buffer + read_offset / 8; }
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public:
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// returns true iff the buffer is valid
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bool valid() { return buffer != 0; }
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// returns count of remaining readable bits
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int unread() { return write_offset - read_offset; }
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// returns true if a recent read operation would have overrun the buffer
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bool underrun();
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// skip ahead a number of bits
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void skip(u32 bits);
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public:
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// insertion
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void write1(u8 data); // data MUST be 1 or 0
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template<class T> void write(T data)
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{
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grow(sizeof(T) * 8);
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u32 byte_offset = write_offset / 8;
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u32 shift = write_offset % 8;
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if (shift)
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{
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buffer[byte_offset] |= (u8)(data << shift);
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data = data >> (8 - shift);
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++byte_offset;
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}
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*(T*)(buffer + byte_offset) = data;
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write_offset += sizeof(T) * 8;
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}
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template<> void write(s8 data) { write((u8)data); }
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template<> void write(s16 data) { write((u16)data); }
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template<> void write(s32 data) { write((u32)data); }
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template<> void write(s64 data) { write((u64)data); }
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template<> void write(float data) { write(*(u32*)&data); }
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template<> void write(double data) { write(*(u64*)&data); }
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void writeBits(u32 data, int count);
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void writeBytes(const void *data, u32 byte_count);
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public:
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// stream-mode insertion
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BitStream &operator<<(const char *data) { writeBytes(data, (u32)strlen(data)); return *this; }
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template<class T> BitStream &operator<<(T data) { write(data); return *this; }
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template<u32 N_BITS> BitStream &operator<<(const bs_bit::set<N_BITS> &n) { writeBits(n.bits, N_BITS); return *this; }
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template<> BitStream &operator<<(const bs_bit::set<1> &n) { write1((u8)n.bits); return *this; }
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template<> BitStream &operator<<(const bs_bit::set<8> &n) { write((u8)n.bits); return *this; }
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template<> BitStream &operator<<(const bs_bit::set<16> &n) { write((u16)n.bits); return *this; }
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template<> BitStream &operator<<(const bs_bit::set<32> &n) { write((u32)n.bits); return *this; }
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BitStream &operator<<(const bs_byte::set &n) { writeBytes(n.ref, n.bytes); return *this; }
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public:
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// extraction
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u8 read1();
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template<class T> void read(T &data)
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{
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const u32 bits = sizeof(T) * 8;
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if (read_offset + bits > write_offset)
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{
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read_underrun = true;
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return;
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}
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u32 byte_offset = read_offset / 8;
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u32 shift = read_offset % 8;
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if (shift)
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data = (*(T*)(buffer + byte_offset + 1) << (8 - shift)) | (buffer[byte_offset] >> shift);
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else
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data = *(T*)(buffer + byte_offset);
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read_offset += bits;
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}
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template<> void read(float &data) { read((u32&)data); }
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template<> void read(double &data) { write(*(u64*)&data); }
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template<class T> T read() { T temp; read(temp); return temp; }
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u32 readBits(u32 count);
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void readBytes(void *data, u32 byte_count);
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public:
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// stream-mode extraction
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template<class T> BitStream &operator>>(T &data) { read(data); return *this; }
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template<u32 N_BITS> BitStream &operator>>(const bs_bit::get<N_BITS> &n) { n.ref = readBits(N_BITS); return *this; }
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template<> BitStream &operator>>(const bs_bit::get<1> &n) { n.ref = read1(); return *this; }
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template<> BitStream &operator>>(const bs_bit::get<8> &n) { n.ref = read<u8>(); return *this; }
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template<> BitStream &operator>>(const bs_bit::get<16> &n) { n.ref = read<u16>(); return *this; }
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template<> BitStream &operator>>(const bs_bit::get<32> &n) { read(n.ref); return *this; }
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BitStream &operator>>(const bs_byte::get &n) { readBytes(n.ref, n.bytes); return *this; }
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};
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} // namespace cat
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#endif // CAT_BIT_STREAM_HPP
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