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// Data reader interface for uniform access
// File_Extractor 0.4.0
#ifndef DATA_READER_H
#define DATA_READER_H
#include "blargg_common.h"
// Supports reading and finding out how many bytes are remaining
class Data_Reader {
public:
virtual ~Data_Reader() { }
static const char eof_error []; // returned by read() when request goes beyond end
// Read at most count bytes and return number actually read, or <= 0 if error
virtual long read_avail( void*, long n ) = 0;
// Read exactly count bytes and return error if they couldn't be read
virtual blargg_err_t read( void*, long count );
// Number of bytes remaining until end of file
virtual long remain() const = 0;
// Read and discard count bytes
virtual blargg_err_t skip( long count );
public:
Data_Reader() { }
typedef blargg_err_t error_t; // deprecated
private:
// noncopyable
Data_Reader( const Data_Reader& );
Data_Reader& operator = ( const Data_Reader& );
};
// Supports seeking in addition to Data_Reader operations
class File_Reader : public Data_Reader {
public:
// Size of file
virtual long size() const = 0;
// Current position in file
virtual long tell() const = 0;
// Go to new position
virtual blargg_err_t seek( long ) = 0;
long remain() const;
blargg_err_t skip( long n );
};
// Disk file reader
class Std_File_Reader : public File_Reader {
public:
blargg_err_t open( const char* path );
void close();
public:
Std_File_Reader();
~Std_File_Reader();
long size() const;
blargg_err_t read( void*, long );
long read_avail( void*, long );
long tell() const;
blargg_err_t seek( long );
private:
void* file_;
};
// Treats range of memory as a file
class Mem_File_Reader : public File_Reader {
public:
Mem_File_Reader( const void*, long size );
public:
long size() const;
long read_avail( void*, long );
long tell() const;
blargg_err_t seek( long );
private:
const char* const begin;
const long size_;
long pos;
};
// Makes it look like there are only count bytes remaining
class Subset_Reader : public Data_Reader {
public:
Subset_Reader( Data_Reader*, long count );
public:
long remain() const;
long read_avail( void*, long );
private:
Data_Reader* in;
long remain_;
};
// Joins already-read header and remaining data into original file (to avoid seeking)
class Remaining_Reader : public Data_Reader {
public:
Remaining_Reader( void const* header, long size, Data_Reader* );
public:
long remain() const;
long read_avail( void*, long );
blargg_err_t read( void*, long );
private:
char const* header;
char const* header_end;
Data_Reader* in;
long read_first( void* out, long count );
};
// Invokes callback function to read data. Size of data must be specified in advance.
class Callback_Reader : public Data_Reader {
public:
typedef const char* (*callback_t)( void* data, void* out, long count );
Callback_Reader( callback_t, long size, void* data = 0 );
public:
long read_avail( void*, long );
blargg_err_t read( void*, long );
long remain() const;
private:
callback_t const callback;
void* const data;
long remain_;
};
#ifdef HAVE_ZLIB_H
// Gzip compressed file reader
class Gzip_File_Reader : public File_Reader {
public:
blargg_err_t open( const char* path );
void close();
public:
Gzip_File_Reader();
~Gzip_File_Reader();
long size() const;
long read_avail( void*, long );
long tell() const;
blargg_err_t seek( long );
private:
void* file_;
long size_;
};
#endif
#endif
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