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115 lines
3.9 KiB
C++
115 lines
3.9 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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//=============================================================================
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//
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// Class AlignedStream
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// A simple wrapper around stream that controls data padding.
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//
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// Originally, a number of objects in AGS were read and written directly
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// as a data struct in a whole. In order to support backwards compatibility
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// with games made by older versions of AGS, some of the game objects must
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// be read having automatic data alignment in mind.
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//-----------------------------------------------------------------------------
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//
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// AlignedStream uses the underlying stream, it overrides the reading and
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// writing, and inserts extra data padding when needed.
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//
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// Aligned stream works either in read or write mode, it cannot be opened in
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// combined mode.
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//
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// AlignedStream does not support seek, hence moving stream pointer to random
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// position will break padding count logic.
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//
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//=============================================================================
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#ifndef AGS_SHARED_UTIL_ALIGNEDSTREAM_H
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#define AGS_SHARED_UTIL_ALIGNEDSTREAM_H
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#include "ags/shared/util/proxy_stream.h"
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namespace AGS3 {
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namespace AGS {
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namespace Shared {
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enum AlignedStreamMode {
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kAligned_Read,
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kAligned_Write
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};
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class AlignedStream : public ProxyStream {
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public:
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AlignedStream(Stream *stream, AlignedStreamMode mode,
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ObjectOwnershipPolicy stream_ownership_policy = kReleaseAfterUse,
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size_t base_alignment = sizeof(int16_t));
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~AlignedStream() override;
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// Read/Write cumulated padding and reset block counter
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void Reset();
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void Close() override;
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bool CanRead() const override;
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bool CanWrite() const override;
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bool CanSeek() const override;
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size_t Read(void *buffer, size_t size) override;
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int32_t ReadByte() override;
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int16_t ReadInt16() override;
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int32_t ReadInt32() override;
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int64_t ReadInt64() override;
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size_t ReadArray(void *buffer, size_t elem_size, size_t count) override;
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size_t ReadArrayOfInt16(int16_t *buffer, size_t count) override;
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size_t ReadArrayOfInt32(int32_t *buffer, size_t count) override;
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size_t ReadArrayOfInt64(int64_t *buffer, size_t count) override;
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size_t Write(const void *buffer, size_t size) override;
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int32_t WriteByte(uint8_t b) override;
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size_t WriteInt16(int16_t val) override;
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size_t WriteInt32(int32_t val) override;
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size_t WriteInt64(int64_t val) override;
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size_t WriteArray(const void *buffer, size_t elem_size, size_t count) override;
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size_t WriteArrayOfInt16(const int16_t *buffer, size_t count) override;
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size_t WriteArrayOfInt32(const int32_t *buffer, size_t count) override;
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size_t WriteArrayOfInt64(const int64_t *buffer, size_t count) override;
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bool Seek(soff_t offset, StreamSeek origin) override;
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protected:
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void ReadPadding(size_t next_type);
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void WritePadding(size_t next_type);
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void FinalizeBlock();
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private:
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static const size_t LargestPossibleType = sizeof(int64_t);
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AlignedStreamMode _mode;
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size_t _baseAlignment;
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size_t _maxAlignment;
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int64_t _block;
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};
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} // namespace Shared
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} // namespace AGS
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} // namespace AGS3
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#endif
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