anim_ra1.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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 <http://www.gnu.org/licenses/>.
 *
 */

#ifndef SCUMM_SMUSH_REBEL_ANIM_RA1_H
#define SCUMM_SMUSH_REBEL_ANIM_RA1_H

#include "common/endian.h"
#include "common/stream.h"

namespace Scumm {

struct RA1AnimChunk {
    uint32 tag;
    uint32 size;
    int64 offset;
    int64 dataOffset;
    int64 endOffset;
    int64 nextOffset;
    const byte *data;
};

class RA1AnimChunkIterator {
public:
    RA1AnimChunkIterator(const byte *data, uint32 size)
        : _data(data), _offset(0), _endOffset(size) {}

    RA1AnimChunkIterator(const byte *data, uint32 startOffset, uint32 endOffset)
        : _data(data), _offset(startOffset), _endOffset(endOffset) {
        if (_offset > _endOffset)
            _offset = _endOffset;
    }

    bool next(RA1AnimChunk &chunk) {
        if (_data == nullptr || _offset + 8 > _endOffset)
            return false;

        const uint32 size = READ_BE_UINT32(_data + _offset + 4);
        const uint32 dataOffset = _offset + 8;
        if (size > _endOffset - dataOffset) {
            _offset = _endOffset;
            return false;
        }

        chunk.tag = READ_BE_UINT32(_data + _offset);
        chunk.size = size;
        chunk.offset = _offset;
        chunk.dataOffset = dataOffset;
        chunk.endOffset = dataOffset + size;
        chunk.nextOffset = chunk.endOffset + (size & 1);
        if (chunk.nextOffset > _endOffset)
            chunk.nextOffset = _endOffset;
        chunk.data = _data + dataOffset;

        _offset = (uint32)chunk.nextOffset;
        return true;
    }

private:
    const byte *_data;
    uint32 _offset;
    uint32 _endOffset;
};

class RA1AnimStreamChunkIterator {
public:
    RA1AnimStreamChunkIterator(Common::SeekableReadStream &stream, int64 endOffset)
        : _stream(stream), _endOffset(endOffset) {}

    bool next(RA1AnimChunk &chunk) {
        if (_stream.pos() + 8 > _endOffset)
            return false;

        const int64 chunkOffset = _stream.pos();
        const uint32 tag = _stream.readUint32BE();
        const uint32 size = _stream.readUint32BE();
        const int64 dataOffset = _stream.pos();
        const int64 endOffset = dataOffset + size;
        if (endOffset < dataOffset || endOffset > _endOffset)
            return false;

        chunk.tag = tag;
        chunk.size = size;
        chunk.offset = chunkOffset;
        chunk.dataOffset = dataOffset;
        chunk.endOffset = endOffset;
        chunk.nextOffset = endOffset + (size & 1);
        if (chunk.nextOffset > _endOffset)
            chunk.nextOffset = _endOffset;
        chunk.data = nullptr;
        return true;
    }

    void skip(const RA1AnimChunk &chunk) {
        _stream.seek(chunk.nextOffset, SEEK_SET);
    }

private:
    Common::SeekableReadStream &_stream;
    int64 _endOffset;
};

class RA1FrameChunkIterator {
public:
    RA1FrameChunkIterator(Common::SeekableReadStream &stream, int32 &remaining)
        : _stream(stream), _remaining(remaining) {}

    bool next(RA1AnimChunk &chunk) {
        while (_remaining > 1) {
            if ((_stream.pos() & 1) && _remaining > 0) {
                const byte pad = _stream.readByte();
                if (pad == 0) {
                    _remaining--;
                } else {
                    _stream.seek(-1, SEEK_CUR);
                }
            }

            if (_remaining < 8) {
                _stream.skip(_remaining);
                _remaining = 0;
                return false;
            }

            const int64 chunkOffset = _stream.pos();
            chunk.tag = _stream.readUint32BE();
            chunk.size = _stream.readUint32BE();
            chunk.offset = chunkOffset;
            chunk.dataOffset = _stream.pos();
            chunk.endOffset = chunk.dataOffset + chunk.size;
            chunk.nextOffset = chunk.endOffset;
            chunk.data = nullptr;
            return true;
        }

        if (_remaining == 1) {
            _stream.skip(1);
            _remaining = 0;
        }
        return false;
    }

    bool fits(const RA1AnimChunk &chunk) const {
        return _remaining >= 8 && chunk.size <= (uint32)(_remaining - 8);
    }

    void skip(const RA1AnimChunk &chunk) {
        const int32 consumed = fits(chunk) ? (int32)chunk.size + 8 : _remaining;
        _remaining -= consumed;
        _stream.seek(chunk.endOffset, SEEK_SET);
    }

private:
    Common::SeekableReadStream &_stream;
    int32 &_remaining;
};

} // End of namespace Scumm

#endif