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Managed FLAC encoder/decoder based on Flake, initial revision
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chudov
245
CUETools.Codecs.FLAKE/BitReader.cs
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245
CUETools.Codecs.FLAKE/BitReader.cs
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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.FLAKE
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{
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class BitReader
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{
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byte[] buffer;
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byte[] byte_to_unary_table;
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int pos, len;
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int _bitaccumulator;
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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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byte_to_unary_table = new byte[] {
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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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}
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/* supports reading 1 to 24 bits, in big endian format */
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public uint readbits_24(int bits)
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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]);
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result <<= _bitaccumulator;
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result >>= 32 - 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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return result;
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}
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public uint readbits_8(int bits)
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{
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uint result = (((uint)buffer[pos]) << 24) | (((uint)buffer[pos + 1]) << 16);
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result <<= _bitaccumulator;
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result >>= 32 - 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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return result;
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}
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public uint peekbits_24(int bits)
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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]);
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result <<= _bitaccumulator;
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result >>= 32 - bits;
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return result;
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}
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///* supports reading 1 to 16 bits, in big endian format */
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//private unsafe uint peekbits_9(byte* buff, int pos)
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//{
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// uint result = (((uint)buff[pos]) << 8) | (((uint)buff[pos + 1]));
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// result <<= _bitaccumulator;
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// result &= 0x0000ffff;
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// result >>= 7;
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// return result;
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//}
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/* supports reading 1 to 16 bits, in big endian format */
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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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}
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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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if (bits <= 24)
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return readbits_24(bits);
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ulong result = (((ulong)buffer[pos]) << 32) | (((ulong)buffer[pos + 1]) << 24) | (((ulong)buffer[pos + 2]) << 16) | (((ulong)buffer[pos + 3]) << 8) | ((ulong)buffer[pos + 4]);
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result <<= _bitaccumulator;
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result &= 0x00ffffffffff;
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result >>= 40 - 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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return (uint)result;
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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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int new_accumulator;
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uint result = buffer[pos];
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result <<= _bitaccumulator;
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result = result >> 7 & 1;
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new_accumulator = (_bitaccumulator + 1);
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pos += (new_accumulator / 8);
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_bitaccumulator = (new_accumulator % 8);
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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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int result = (buffer[pos] << _bitaccumulator) & 0xff;
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if (result == 0)
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{
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val = 8 - (uint)_bitaccumulator;
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_bitaccumulator = 0;
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pos++;
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return val + read_unary();
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// check eof
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}
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val = byte_to_unary_table[result];
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int new_accumulator = (_bitaccumulator + (int)val + 1);
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pos += (new_accumulator / 8);
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_bitaccumulator = (new_accumulator % 8);
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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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readbits(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 = readbits_24(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_rice_signed8(int k)
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{
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uint msbs = read_unary();
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uint lsbs = readbits_8(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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}
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}
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