84 lines
2.7 KiB
C++
84 lines
2.7 KiB
C++
/* Copyright (C) 2009 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. 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 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* this layer allows for other compression methods/libraries
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* besides ZLib. it also simplifies the interface for user code and
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* does error checking, etc.
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*/
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#ifndef INCLUDED_CODEC
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#define INCLUDED_CODEC
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#define CODEC_COMPUTE_CHECKSUM 1
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struct ICodec
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{
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public:
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/**
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* note: the implementation should not check whether any data remains -
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* codecs are sometimes destroyed without completing a transfer.
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**/
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virtual ~ICodec();
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/**
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* @return an upper bound on the output size for the given amount of input.
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* this is used when allocating a single buffer for the whole operation.
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**/
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virtual size_t MaxOutputSize(size_t inSize) const = 0;
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/**
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* clear all previous state and prepare for reuse.
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*
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* this is as if the object were destroyed and re-created, but more
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* efficient since it avoids reallocating a considerable amount of
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* memory (about 200KB for LZ).
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**/
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virtual LibError Reset() = 0;
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/**
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* process (i.e. compress or decompress) data.
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*
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* @param outSize bytes remaining in the output buffer; shall not be zero.
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* @param inConsumed, outProduced how many bytes in the input and
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* output buffers were used. either or both of these can be zero if
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* the input size is small or there's not enough output space.
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**/
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virtual LibError Process(const u8* in, size_t inSize, u8* out, size_t outSize, size_t& inConsumed, size_t& outProduced) = 0;
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/**
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* flush buffers and make sure all output has been produced.
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*
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* @param checksum over all input data.
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* @return error status for the entire operation.
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**/
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virtual LibError Finish(u32& checksum, size_t& outProduced) = 0;
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/**
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* update a checksum to reflect the contents of a buffer.
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*
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* @param checksum the initial value (must be 0 on first call)
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* @return the new checksum. note: after all data has been seen, this is
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* identical to the what Finish would return.
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**/
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virtual u32 UpdateChecksum(u32 checksum, const u8* in, size_t inSize) const = 0;
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};
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typedef shared_ptr<ICodec> PICodec;
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#endif // #ifndef INCLUDED_CODEC
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