/*

Read a buffer by group of bits (not necessarily multiple of 8).

Copyright (C) 2019, Guillaume Gonnet

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program.  If not, see <https://www.gnu.org/licenses/>.

*/

#pragma once

#include <inttypes.h>

namespace maconv {
namespace utils {


// Read a buffer by group of bits (not necessarily multiple of 8).
struct BitReader {

    // Load a buffer of |length| in the reader.
    void Load(uint8_t *data, int length);


    // Is the reader at end?
    bool HasEnded(int n = 0) { return data == end && num_bits <= n; }

    // Ignore a number of bits (n can be > 32).
    void IgnoreBits(int n);


    // Read a single bit.
    virtual uint8_t ReadBit() { return ReadWord(1); };

    // Read a word (i.e. n <= 25 bits).
    virtual uint32_t ReadWord(int n, bool skip = true) = 0;

    // Read a long word (n can be > 25).
    virtual uint32_t ReadLongWord(int n, bool skip = true) = 0;

    // Skip some bits (that has been readed).
    virtual void SkipBits(int n) = 0;


    uint8_t *data; // Current pointer on data.
    uint8_t *end; // Length of the buffer.

    uint32_t bits = 0; // Bit cache.
    int num_bits = 0; // Number of bits in the cache.
};



// BitReader that reads Big Endian integers.
struct BitReaderBE : BitReader {

    // Read a word (i.e. <= 32 bits).
    uint32_t ReadWord(int n, bool skip = true) override;

    // Read a long word (n can be > 25 bits).
    uint32_t ReadLongWord(int n, bool skip = true) override;

    // Skip some bits (that has been readed).
    void SkipBits(int n) override;

    // Refill the bit cache.
    void FillBitCache();
};


// BitReader that reads Little Endian integers.
struct BitReaderLE : BitReader {

    // Read a word (i.e. <= 25 bits).
    uint32_t ReadWord(int n, bool skip = true) override;

    // Read a long word (n can be > 25 bits).
    uint32_t ReadLongWord(int n, bool skip = true) override;

    // Skip some bits (that has been readed).
    void SkipBits(int n) override;

    // Refill the bit cache.
    void FillBitCache();
};


} // namespace utils
} // namespace maconv