emu65816.hpp

SNES game emulator. C and asm files.

/*
*/

#pragma pack (push,4)
struct regpack {
	dword PC; // 24-bit complete program counter
	union {  // Y index register - Used as a pointer, OR as an offset into an array
		dword Y_dummy;
		word Y;
		byte Y_lo;
	};
	union {  // X index register - ''
		dword X_dummy;
		word X;
		byte X_lo;
	};
	struct {
		byte DBR_dummy1; // Must be 0 for assembly to work
		byte DBR_dummy2;
		byte DBR; // Data Bank        - Selects bank of data access (certain addr. modes)
		byte DBR_dummy3;
	};
	union {
		dword D_dummy;
		word D;   // Direct register  - Pointer used to offset direct addressing (bank 0)
	};
	union {  // 8/16 bit accumulator - Used for math and stuff
		dword A_dummy;
		word A;
		byte A_lo;
	};
	union {
		byte P;   // Status register  - i.e. Flags
				  // 7 6 5 4 3 2 1 0    Negative, oVerflow, 16-bit accuMulator, 16-bit
				  // N V M X D I Z C    indeX, bcD mode, Interrupt Disable, Zero, Carry
		dword P_dummy; // Note: if E=1, X is the B(Hardware Break?) flag, and M is always 1
	};
	union {
		dword S_dummy;
		word S;  // Stack register. (bank 0)
	};
	union {
		dword E_dummy;
		boolean E; // Emulation mode flag
	};
};
#pragma pack (pop)

extern "C" {
	extern struct regpack __cdecl reg; // Set of registers when not running.
	void __cdecl doemulate (void);
}