95 lines
3.3 KiB
C++
95 lines
3.3 KiB
C++
// Manages ROM data loaded from file in an efficient manner
|
|
|
|
// Game_Music_Emu $vers
|
|
#ifndef ROM_DATA_H
|
|
#define ROM_DATA_H
|
|
|
|
#include "blargg_common.h"
|
|
#include "Data_Reader.h"
|
|
|
|
/* Loads a ROM file into memory and allows access to it in page-sized chunks.
|
|
|
|
* ROM file consists of header followed by ROM data. Instead of storing the entire
|
|
ROM contents, the file only stores the occupied portion, with the bytes before and
|
|
after that cleared to some value. The size and format of the header is up to the
|
|
caller, as is the starting address of the ROM data following it. File loading is
|
|
performed with a single read, rather than two or more that might otherwise be
|
|
required.
|
|
|
|
* Once ROM data is loaded and its address specified, a pointer to any "page" can
|
|
be obtained. ROM data is mirrored using smallest power of 2 that contains it.
|
|
Addresses not aligned to pages can also be used, but this might cause unexpected
|
|
results.
|
|
|
|
Example with file data of size 0x0C put at address 0x0F, with page size of 8:
|
|
|
|
---------------0123456789AB--------------------0123456789AB---------...
|
|
^ ^ ^ ^ ^ ^ ^ ^ ^
|
|
0 0x08 0x10 0x18 0x20 0x28 0x30 0x38 0x40
|
|
|
|
at_addr(0x00) = pointer to 8 bytes of fill.
|
|
at_addr(0x08) = pointer to 7 bytes of fill, followed by first byte of file.
|
|
at_addr(0x10) = pointer to next 8 bytes of file.
|
|
at_addr(0x18) = pointer to last 3 bytes of file, followed by 5 bytes of fill.
|
|
at_addr(0x20) = pointer to 8 bytes of fill.
|
|
at_addr(0x28) = pointer to 7 bytes of fill, followed by first byte of file.
|
|
etc. */
|
|
|
|
class Rom_Data {
|
|
enum { pad_extra = 8 };
|
|
public:
|
|
typedef unsigned char byte;
|
|
|
|
// Page_size should be a power of 2
|
|
Rom_Data( int page_size );
|
|
|
|
// Loads file into memory, then copies header to *header_out and fills
|
|
// unmapped bank and file data padding with fill. Returns blargg_err_file_type
|
|
// if in.remain() <= header_size.
|
|
blargg_err_t load( Data_Reader& in, int header_size, void* header_out, int fill );
|
|
|
|
// Below, "file data" refers to data AFTER the header
|
|
|
|
// Size of file data
|
|
int file_size() const { return file_size_; }
|
|
|
|
// Pointer to beginning of file data
|
|
byte * begin() { return rom.begin() + pad_size; }
|
|
byte const* begin() const { return rom.begin() + pad_size; }
|
|
|
|
// Pointer to unmapped page cleared with fill value
|
|
byte* unmapped() { return rom.begin(); }
|
|
|
|
// Sets address that file data will start at. Must be set before using following
|
|
// functions, and cannot be set more than once.
|
|
void set_addr( int addr );
|
|
|
|
// Address of first empty page (file size + addr rounded up to multiple of page_size)
|
|
int size() const { return rom.size() - pad_extra + rom_addr; }
|
|
|
|
// Masks address to nearest power of two greater than size()
|
|
int mask_addr( int addr ) const { return addr & mask; }
|
|
|
|
// Pointer to page beginning at addr, or unmapped() if outside data.
|
|
// Mirrored using mask_addr().
|
|
byte* at_addr( int addr );
|
|
|
|
// Frees memory
|
|
void clear();
|
|
|
|
// Implementation
|
|
public:
|
|
~Rom_Data();
|
|
|
|
protected:
|
|
blargg_vector<byte> rom;
|
|
int mask;
|
|
int rom_addr;
|
|
int const pad_size;
|
|
int file_size_;
|
|
|
|
blargg_err_t load_( Data_Reader& in, int header_size, int file_offset );
|
|
};
|
|
|
|
#endif
|