apps/codecs/libgme/rom_data.h

   1 // Common aspects of emulators which use rom data
   2
   3 // Game_Music_Emu 0.5.2
   4 #ifndef ROM_DATA_H
   5 #define ROM_DATA_H
   6
   7 #include "blargg_common.h"
   8 #include "blargg_source.h"
   9
  10 // ROM data handler, used by several Classic_Emu derivitives. Loads file data
  11 // with padding on both sides, allowing direct use in bank mapping. The main purpose
  12 // is to allow all file data to be loaded with only one read() call (for efficiency).
  13
  14 extern const char gme_wrong_file_type []; // declared in gme.h
  15
  16 enum { pad_extra = 8 };
  17 enum { max_bank_size = 0x4000 };
  18 enum { max_pad_size = max_bank_size + pad_extra };
  19 enum { max_rom_size = 2 * max_pad_size };
  20
  21 struct  Rom_Data {
  22         byte* file_data;
  23         unsigned file_size;
  24
  25         int rom_addr;
  26         int bank_size;
  27         int rom_size;
  28         unsigned pad_size;
  29         int mask;
  30         int size; // TODO: eliminate
  31         int rsize_;
  32
  33         // Unmapped space
  34         byte unmapped [max_rom_size];
  35 };
  36
  37 // Initialize rom
  38 static inline void Rom_init( struct Rom_Data* this, int bank_size )
  39 {
  40         this->bank_size = bank_size;
  41         this->pad_size = this->bank_size + pad_extra;
  42         this->rom_size = 2 * this->pad_size;
  43 }
  44
  45 // Load file data, using already-loaded header 'h' if not NULL. Copy header
  46 // from loaded file data into *out and fill unmapped bytes with 'fill'.
  47 blargg_err_t Rom_load( struct Rom_Data* this, const void* data, long size, int header_size, void* header_out, int fill );
  48
  49 // Set address that file data should start at
  50 void Rom_set_addr( struct Rom_Data* this, int addr );
  51
  52 // Mask address to nearest power of two greater than size()
  53 static inline int mask_addr( int addr, int mask )
  54 {
  55         #ifdef check
  56                 check( addr <= mask );
  57         #endif
  58         return addr & mask;
  59 }
  60
  61 // Pointer to page starting at addr. Returns unmapped() if outside data.
  62 static inline byte* Rom_at_addr( struct Rom_Data* this, int addr )
  63 {
  64         unsigned offset = mask_addr( addr, this->mask ) - this->rom_addr;
  65         if ( offset > (unsigned) (this->rsize_ - this->pad_size) )
  66                 offset = 0; // unmapped
  67
  68         if ( offset < this->pad_size ) return &this->unmapped [offset];
  69         else return &this->file_data [offset - this->pad_size];
  70 }
  71
  72
  73 #ifndef GME_APU_HOOK
  74         #define GME_APU_HOOK( emu, addr, data ) ((void) 0)
  75 #endif
  76
  77 #ifndef GME_FRAME_HOOK
  78         #define GME_FRAME_HOOK( emu ) ((void) 0)
  79 #else
  80         #define GME_FRAME_HOOK_DEFINED 1
  81 #endif
  82
  83 #endif