mirror of
https://github.com/RetroDECK/Supermodel.git
synced 2024-11-24 22:55:40 +00:00
281 lines
6.4 KiB
C++
281 lines
6.4 KiB
C++
/**
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** Supermodel
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** A Sega Model 3 Arcade Emulator.
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** Copyright 2011 Bart Trzynadlowski, Nik Henson
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**
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** This file is part of Supermodel.
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**
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** Supermodel 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
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** Software Foundation, either version 3 of the License, or (at your option)
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** any later version.
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**
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** Supermodel is distributed in the hope that it will be useful, but WITHOUT
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** ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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** FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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** more details.
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**
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** You should have received a copy of the GNU General Public License along
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** with Supermodel. If not, see <http://www.gnu.org/licenses/>.
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**/
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/*
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* BlockFile.cpp
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*
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* Block format container file management. Implementation of the CBlockFile
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* class.
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*/
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#include "BlockFile.h"
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#include <cstdio>
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#include <cstring>
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#include <cstdint>
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#include "Supermodel.h"
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/******************************************************************************
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Output Functions
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******************************************************************************/
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void CBlockFile::ReadString(std::string *str, uint32_t length)
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{
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if (NULL == fp)
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return;
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str->clear();
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//TODO: use fstream to get rid of this ugly hack
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bool keep_loading = true;
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for (size_t i = 0; i < length; i++)
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{
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char c;
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fread(&c, sizeof(char), 1, fp);
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if (keep_loading)
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{
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if (!c)
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keep_loading = false;
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else
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*str += c;
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}
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}
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}
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unsigned CBlockFile::ReadBytes(void *data, uint32_t numBytes)
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{
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if (NULL == fp)
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return 0;
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return fread(data, sizeof(uint8_t), numBytes, fp);
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}
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unsigned CBlockFile::ReadDWord(uint32_t *data)
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{
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if (NULL == fp)
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return 0;
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fread(data, sizeof(uint32_t), 1, fp);
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return 4;
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}
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void CBlockFile::UpdateBlockSize(void)
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{
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long int curPos;
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unsigned newBlockSize;
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if (NULL == fp)
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return;
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curPos = ftell(fp); // save current file position
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fseek(fp, blockStartPos, SEEK_SET);
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newBlockSize = curPos - blockStartPos;
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fwrite(&newBlockSize, sizeof(uint32_t), 1, fp);
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fseek(fp, curPos, SEEK_SET); // go back
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}
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void CBlockFile::WriteByte(uint8_t data)
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{
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if (NULL == fp)
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return;
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fwrite(&data, sizeof(uint8_t), 1, fp);
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UpdateBlockSize();
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}
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void CBlockFile::WriteDWord(uint32_t data)
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{
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if (NULL == fp)
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return;
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fwrite(&data, sizeof(uint32_t), 1, fp);
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UpdateBlockSize();
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}
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void CBlockFile::WriteBytes(const void *data, uint32_t numBytes)
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{
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if (NULL == fp)
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return;
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fwrite(data, sizeof(uint8_t), numBytes, fp);
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UpdateBlockSize();
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}
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void CBlockFile::WriteBlockHeader(const std::string &name, const std::string &comment)
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{
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if (NULL == fp)
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return;
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// Record current block starting position
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blockStartPos = ftell(fp);
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// Write the total block length field
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WriteDWord(0); // will be automatically updated as we write the file
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// Write name and comment lengths
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WriteDWord(name.size() + 1);
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WriteDWord(comment.size() + 1);
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Write(name);
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Write(comment);
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// Record the start of the current data section
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dataStartPos = ftell(fp);
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}
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/******************************************************************************
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Block Format Container File Implementation
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Files are just a consecutive array of blocks that must be searched.
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Block Format
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------------
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blockLength (uint32_t) Total length of block in bytes.
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nameLength (uint32_t) Length of name field including terminating 0 (up to
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1025).
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commentLength (uint32_t) Same as above, but for comment string.
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name ... Name string (null-terminated, up to 1025 bytes).
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comment ... Comment string (same as above).
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data ... Raw data (blockLength - total header size).
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******************************************************************************/
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unsigned CBlockFile::Read(void *data, uint32_t numBytes)
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{
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if (mode == 'r')
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return ReadBytes(data, numBytes);
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return 0;
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}
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unsigned CBlockFile::Read(bool *value)
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{
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uint8_t byte;
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unsigned numBytes = Read(&byte, sizeof(byte));
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if (numBytes > 0)
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*value = byte != 0;
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return numBytes;
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}
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void CBlockFile::Write(const void *data, uint32_t numBytes)
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{
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if (mode == 'w')
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WriteBytes(data, numBytes);
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}
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void CBlockFile::Write(bool value)
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{
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uint8_t byte = value ? 1 : 0;
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Write(&byte, sizeof(byte));
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}
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void CBlockFile::Write(const std::string &str)
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{
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if (mode == 'w')
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WriteBytes(str.c_str(), str.length() + 1);
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}
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void CBlockFile::NewBlock(const std::string &name, const std::string &comment)
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{
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if (mode == 'w')
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WriteBlockHeader(name, comment);
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}
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bool CBlockFile::FindBlock(const std::string &name)
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{
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if (mode != 'r')
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return FAIL;
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fseek(fp, 0, SEEK_SET);
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long int curPos = 0;
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while (curPos < fileSize)
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{
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blockStartPos = curPos;
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// Read header
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uint32_t block_length;
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uint32_t name_length;
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uint32_t comment_length;
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curPos += ReadDWord(&block_length);
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curPos += ReadDWord(&name_length);
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curPos += ReadDWord(&comment_length);
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std::string block_name;
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ReadString(&block_name, name_length);
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// Is this the block we want?
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if (block_name == name)
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{
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fseek(fp, blockStartPos + 12 + name_length + comment_length, SEEK_SET); // move to beginning of data
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dataStartPos = ftell(fp);
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return OKAY;
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}
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// Move to next block
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fseek(fp, blockStartPos + block_length, SEEK_SET);
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curPos = blockStartPos + block_length;
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if (block_length == 0) // this would never advance
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break;
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}
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return FAIL;
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}
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bool CBlockFile::Create(const std::string &file, const std::string &headerName, const std::string &comment)
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{
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fp = fopen(file.c_str(), "wb");
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if (NULL == fp)
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return FAIL;
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mode = 'w';
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WriteBlockHeader(headerName, comment);
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return OKAY;
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}
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bool CBlockFile::Load(const std::string &file)
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{
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fp = fopen(file.c_str(), "rb");
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if (NULL == fp)
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return FAIL;
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mode = 'r';
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// TODO: is this a valid block file?
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// Get the file size
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fseek(fp, 0, SEEK_END);
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fileSize = ftell(fp);
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fseek(fp, 0, SEEK_SET);
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return OKAY;
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}
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void CBlockFile::Close(void)
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{
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if (fp != NULL)
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fclose(fp);
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fp = NULL;
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mode = 0;
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}
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CBlockFile::CBlockFile(void)
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{
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fp = NULL;
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mode = 0; // neither reading nor writing (do nothing)
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}
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CBlockFile::~CBlockFile(void)
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{
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if (fp != NULL) // in case user forgot
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fclose(fp);
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fp = NULL;
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mode = 0;
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}
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