bsnes/snesreader/fex/Data_Reader.h

265 lines
6.8 KiB
C++
Executable File

// Lightweight interface for reading data from byte stream
// File_Extractor 1.0.0
#ifndef DATA_READER_H
#define DATA_READER_H
#include "blargg_common.h"
/* Some functions accept a long instead of int for convenience where caller has
a long due to some other interface, and would otherwise have to get a warning,
or cast it (and verify that it wasn't outside the range of an int).
To really support huge (>2GB) files, long isn't a solution, since there's no
guarantee it's more than 32 bits. We'd need to use long long (if available), or
something compiler-specific, and change all places file sizes or offsets are
used. */
// Supports reading and finding out how many bytes are remaining
class Data_Reader {
public:
// Reads min(*n,remain()) bytes and sets *n to this number, thus trying to read more
// tham remain() bytes doesn't result in error, just *n being set to remain().
blargg_err_t read_avail( void* p, int* n );
blargg_err_t read_avail( void* p, long* n );
// Reads exactly n bytes, or returns error if they couldn't ALL be read.
// Reading past end of file results in blargg_err_file_eof.
blargg_err_t read( void* p, int n );
// Number of bytes remaining until end of file
int remain() const { return remain_; }
// Reads and discards n bytes. Skipping past end of file results in blargg_err_file_eof.
blargg_err_t skip( int n );
virtual ~Data_Reader() { }
private:
// noncopyable
Data_Reader( const Data_Reader& );
Data_Reader& operator = ( const Data_Reader& );
// Derived interface
protected:
Data_Reader() : remain_( 0 ) { }
// Sets remain
void set_remain( int n ) { assert( n >= 0 ); remain_ = n; }
// Do same as read(). Guaranteed that 0 < n <= remain(). Value of remain() is updated
// AFTER this call succeeds, not before. set_remain() should NOT be called from this.
virtual blargg_err_t read_v( void*, int n ) BLARGG_PURE( { (void)n; return blargg_ok; } )
// Do same as skip(). Guaranteed that 0 < n <= remain(). Default just reads data
// and discards it. Value of remain() is updated AFTER this call succeeds, not
// before. set_remain() should NOT be called from this.
virtual blargg_err_t skip_v( int n );
// Implementation
public:
BLARGG_DISABLE_NOTHROW
private:
int remain_;
};
// Supports seeking in addition to Data_Reader operations
class File_Reader : public Data_Reader {
public:
// Size of file
int size() const { return size_; }
// Current position in file
int tell() const { return size_ - remain(); }
// Goes to new position
blargg_err_t seek( int );
// Derived interface
protected:
// Sets size and resets position
void set_size( int n ) { size_ = n; Data_Reader::set_remain( n ); }
void set_size( long n ) { set_size( STATIC_CAST(int, n) ); }
// Sets reported position
void set_tell( int i ) { assert( 0 <= i && i <= size_ ); Data_Reader::set_remain( size_ - i ); }
// Do same as seek(). Guaranteed that 0 <= n <= size(). Value of tell() is updated
// AFTER this call succeeds, not before. set_* functions should NOT be called from this.
virtual blargg_err_t seek_v( int n ) BLARGG_PURE( { (void)n; return blargg_ok; } )
// Implementation
protected:
File_Reader() : size_( 0 ) { }
virtual blargg_err_t skip_v( int );
private:
int size_;
void set_remain(); // avoid accidental use of set_remain
};
// Reads from file on disk
class Std_File_Reader : public File_Reader {
public:
// Opens file
blargg_err_t open( const char path [] );
// Closes file if one was open
void close();
// Switches to unbuffered mode. Useful if buffering is already being
// done at a higher level.
void make_unbuffered();
// Implementation
public:
Std_File_Reader();
virtual ~Std_File_Reader();
protected:
virtual blargg_err_t read_v( void*, int );
virtual blargg_err_t seek_v( int );
private:
void* file_;
};
// Treats range of memory as a file
class Mem_File_Reader : public File_Reader {
public:
Mem_File_Reader( const void* begin, long size );
// Implementation
protected:
virtual blargg_err_t read_v( void*, int );
virtual blargg_err_t seek_v( int );
private:
const char* const begin;
};
// Allows only count bytes to be read from reader passed
class Subset_Reader : public Data_Reader {
public:
Subset_Reader( Data_Reader*, int count );
// Implementation
protected:
virtual blargg_err_t read_v( void*, int );
private:
Data_Reader* const in;
};
// Joins already-read header and remaining data into original file.
// Meant for cases where you've already read header and don't want
// to seek and re-read data (for efficiency).
class Remaining_Reader : public Data_Reader {
public:
Remaining_Reader( void const* header, int header_size, Data_Reader* );
// Implementation
protected:
virtual blargg_err_t read_v( void*, int );
private:
Data_Reader* const in;
void const* header;
int header_remain;
};
// Invokes callback function to read data
extern "C" { // necessary to be usable from C
typedef const char* (*callback_reader_func_t)(
void* user_data, // Same value passed to constructor
void* out, // Buffer to place data into
int count // Number of bytes to read
);
}
class Callback_Reader : public Data_Reader {
public:
typedef callback_reader_func_t callback_t;
Callback_Reader( callback_t, long size, void* user_data );
// Implementation
protected:
virtual blargg_err_t read_v( void*, int );
private:
callback_t const callback;
void* const user_data;
};
// Invokes callback function to read data
extern "C" { // necessary to be usable from C
typedef const char* (*callback_file_reader_func_t)(
void* user_data, // Same value passed to constructor
void* out, // Buffer to place data into
int count, // Number of bytes to read
int pos // Position in file to read from
);
}
class Callback_File_Reader : public File_Reader {
public:
typedef callback_file_reader_func_t callback_t;
Callback_File_Reader( callback_t, long size, void* user_data );
// Implementation
protected:
virtual blargg_err_t read_v( void*, int );
virtual blargg_err_t seek_v( int );
private:
callback_t const callback;
void* const user_data;
};
#ifdef HAVE_ZLIB_H
// Reads file compressed with gzip (or uncompressed)
class Gzip_File_Reader : public File_Reader {
public:
// Opens possibly gzipped file
blargg_err_t open( const char path [] );
// Closes file if one was open
void close();
// Implementation
public:
Gzip_File_Reader();
~Gzip_File_Reader();
protected:
virtual blargg_err_t read_v( void*, int );
virtual blargg_err_t seek_v( int );
private:
// void* so "zlib.h" doesn't have to be included here
void* file_;
};
#endif
char* blargg_to_utf8( const wchar_t* );
wchar_t* blargg_to_wide( const char* );
#endif