visualboyadvance-m/fex/fex/Data_Reader.h

294 lines
8.3 KiB
C++

// 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