101 lines
2.6 KiB
C++
101 lines
2.6 KiB
C++
/*
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Read a buffer by group of bits (not necessarily multiple of 8).
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Copyright (C) 2019, Guillaume Gonnet
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This program is free software: you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
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PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <inttypes.h>
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namespace maconv {
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namespace utils {
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// Read a buffer by group of bits (not necessarily multiple of 8).
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struct BitReader {
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// Load a buffer of |length| in the reader.
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void Load(uint8_t *data, int length);
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// Is the reader at end?
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bool HasEnded(int n = 0) { return data == end && num_bits <= n; }
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// Ignore a number of bits (n can be > 32).
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void IgnoreBits(int n);
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// Read a single bit.
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virtual uint8_t ReadBit() { return ReadWord(1); };
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// Read a word (i.e. n <= 25 bits).
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virtual uint32_t ReadWord(int n, bool skip = true) = 0;
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// Read a long word (n can be > 25).
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virtual uint32_t ReadLongWord(int n, bool skip = true) = 0;
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// Skip some bits (that has been readed).
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virtual void SkipBits(int n) = 0;
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uint8_t *data; // Current pointer on data.
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uint8_t *end; // Length of the buffer.
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uint32_t bits = 0; // Bit cache.
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int num_bits = 0; // Number of bits in the cache.
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};
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// BitReader that reads Big Endian integers.
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struct BitReaderBE : BitReader {
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// Read a word (i.e. <= 32 bits).
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uint32_t ReadWord(int n, bool skip = true) override;
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// Read a long word (n can be > 25 bits).
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uint32_t ReadLongWord(int n, bool skip = true) override;
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// Skip some bits (that has been readed).
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void SkipBits(int n) override;
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// Refill the bit cache.
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void FillBitCache();
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};
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// BitReader that reads Little Endian integers.
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struct BitReaderLE : BitReader {
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// Read a word (i.e. <= 25 bits).
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uint32_t ReadWord(int n, bool skip = true) override;
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// Read a long word (n can be > 25 bits).
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uint32_t ReadLongWord(int n, bool skip = true) override;
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// Skip some bits (that has been readed).
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void SkipBits(int n) override;
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// Refill the bit cache.
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void FillBitCache();
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};
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} // namespace utils
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} // namespace maconv
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