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ALAC encoder
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chudov
331
CUETools.Codecs/BitReader.cs
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331
CUETools.Codecs/BitReader.cs
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/**
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* CUETools.Codecs: common audio encoder/decoder routines
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* Copyright (c) 2009 Gregory S. Chudov
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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using System;
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using System.Collections.Generic;
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using System.Text;
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namespace CUETools.Codecs
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{
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unsafe public class BitReader
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{
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byte* buffer;
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int pos, len;
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int _bitaccumulator;
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uint cache;
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public static int log2i(int v)
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{
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return log2i((uint)v);
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}
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public static int log2i(uint v)
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{
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int n = 0;
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if (0 != (v & 0xffff0000)) { v >>= 16; n += 16; }
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if (0 != (v & 0xff00)) { v >>= 8; n += 8; }
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return n + byte_to_log2_table[v];
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}
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public static readonly byte[] byte_to_unary_table = new byte[]
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{
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8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
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3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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public static readonly byte[] byte_to_log2_table = new byte[]
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{
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0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
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4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
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5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
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5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
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6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
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6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
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};
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public int Position
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{
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get { return pos; }
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}
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public byte* Buffer
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{
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get
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{
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return buffer;
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}
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}
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public BitReader(byte* _buffer, int _pos, int _len)
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{
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buffer = _buffer;
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pos = _pos;
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len = _len;
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_bitaccumulator = 0;
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cache = peek4();
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}
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public uint peek4()
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{
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//uint result = ((((uint)buffer[pos]) << 24) | (((uint)buffer[pos + 1]) << 16) | (((uint)buffer[pos + 2]) << 8) | ((uint)buffer[pos + 3])) << _bitaccumulator;
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byte* b = buffer + pos;
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uint result = *(b++);
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result = (result << 8) + *(b++);
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result = (result << 8) + *(b++);
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result = (result << 8) + *(b++);
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result <<= _bitaccumulator;
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return result;
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}
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/* skip any number of bits */
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public void skipbits(int bits)
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{
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int new_accumulator = (_bitaccumulator + bits);
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pos += (new_accumulator >> 3);
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_bitaccumulator = (new_accumulator & 7);
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cache = peek4();
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}
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/* skip up to 8 bits */
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public void skipbits8(int bits)
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{
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cache <<= bits;
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int new_accumulator = (_bitaccumulator + bits);
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pos += (new_accumulator >> 3);
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_bitaccumulator = (new_accumulator & 7);
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cache |= ((uint)buffer[pos + 3] << _bitaccumulator);
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}
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/* supports reading 1 to 24 bits, in big endian format */
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public uint readbits24(int bits)
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{
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//uint result = peek4() >> (32 - bits);
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uint result = cache >> (32 - bits);
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skipbits(bits);
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return result;
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}
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public uint peekbits24(int bits)
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{
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return cache >> 32 - bits;
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}
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/* supports reading 1 to 32 bits, in big endian format */
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public uint readbits(int bits)
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{
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uint result = cache >> 32 - bits;
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if (bits <= 24)
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{
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skipbits(bits);
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return result;
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}
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skipbits(24);
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result |= cache >> 56 - bits;
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skipbits(bits - 24);
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return result;
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}
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public ulong readbits64(int bits)
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{
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if (bits <= 24)
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return readbits24(bits);
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ulong result = readbits24(24);
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bits -= 24;
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if (bits <= 24)
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return (result << bits) | readbits24(bits);
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result = (result << 24) | readbits24(24);
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bits -= 24;
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return (result << bits) | readbits24(bits);
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}
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/* reads a single bit */
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public uint readbit()
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{
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uint result = cache >> 31;
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skipbits8(1);
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return result;
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}
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public uint read_unary()
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{
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uint val = 0;
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uint result = cache >> 24;
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while (result == 0)
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{
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val += 8;
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skipbits8(8);
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result = cache >> 24;
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}
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val += byte_to_unary_table[result];
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skipbits8((int)(val & 7) + 1);
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return val;
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}
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public void flush()
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{
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if (_bitaccumulator > 0)
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skipbits8(8 - _bitaccumulator);
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}
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public int readbits_signed(int bits)
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{
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int val = (int)readbits(bits);
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val <<= (32 - bits);
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val >>= (32 - bits);
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return val;
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}
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public uint read_utf8()
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{
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uint x = readbits(8);
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uint v;
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int i;
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if (0 == (x & 0x80))
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{
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v = x;
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i = 0;
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}
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else if (0xC0 == (x & 0xE0)) /* 110xxxxx */
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{
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v = x & 0x1F;
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i = 1;
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}
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else if (0xE0 == (x & 0xF0)) /* 1110xxxx */
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{
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v = x & 0x0F;
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i = 2;
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}
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else if (0xF0 == (x & 0xF8)) /* 11110xxx */
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{
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v = x & 0x07;
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i = 3;
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}
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else if (0xF8 == (x & 0xFC)) /* 111110xx */
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{
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v = x & 0x03;
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i = 4;
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}
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else if (0xFC == (x & 0xFE)) /* 1111110x */
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{
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v = x & 0x01;
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i = 5;
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}
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else if (0xFE == x) /* 11111110 */
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{
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v = 0;
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i = 6;
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}
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else
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throw new Exception("invalid utf8 encoding");
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for (; i > 0; i--)
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{
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x = readbits(8);
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if (0x80 != (x & 0xC0)) /* 10xxxxxx */
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throw new Exception("invalid utf8 encoding");
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v <<= 6;
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v |= (x & 0x3F);
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}
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return v;
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}
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public int read_rice_signed(int k)
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{
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uint msbs = read_unary();
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uint lsbs = readbits24(k);
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uint uval = (msbs << k) | lsbs;
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return (int)(uval >> 1 ^ -(int)(uval & 1));
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}
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public int read_unary_signed()
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{
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uint uval = read_unary();
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return (int)(uval >> 1 ^ -(int)(uval & 1));
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}
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public void read_rice_block(int n, int k, int* r)
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{
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fixed (byte* unary_table = byte_to_unary_table)
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{
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if (k == 0)
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for (int i = n; i > 0; i--)
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*(r++) = read_unary_signed();
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else if (k <= 8)
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for (int i = n; i > 0; i--)
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{
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//*(r++) = read_rice_signed((int)k);
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uint bits = unary_table[cache >> 24];
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uint msbs = bits;
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while (bits == 8)
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{
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skipbits8(8);
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bits = unary_table[cache >> 24];
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msbs += bits;
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}
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skipbits8((int)(msbs & 7) + 1);
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uint uval = (msbs << k) | (cache >> (32 - k));
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skipbits8(k);
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*(r++) = (int)(uval >> 1 ^ -(int)(uval & 1));
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}
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else
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for (int i = n; i > 0; i--)
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{
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//*(r++) = read_rice_signed((int)k);
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uint bits = unary_table[cache >> 24];
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uint msbs = bits;
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while (bits == 8)
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{
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skipbits8(8);
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bits = unary_table[cache >> 24];
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msbs += bits;
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}
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skipbits8((int)(msbs & 7) + 1);
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uint uval = (msbs << k) | (cache >> (32 - k));
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skipbits(k);
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*(r++) = (int)(uval >> 1 ^ -(int)(uval & 1));
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}
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}
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}
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}
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}
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