81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
|
// Nintendo Game Boy CPU emulator
|
||
|
|
|
||
|
|
// Game_Music_Emu 0.6-pre
|
||
|
|
#ifndef GB_CPU_H
|
||
|
|
#define GB_CPU_H
|
||
|
|
|
||
|
|
#include "blargg_common.h"
|
||
|
|
#include "blargg_source.h"
|
||
|
|
|
||
|
|
typedef int addr_t;
|
||
|
|
|
||
|
|
// Emulator reads this many bytes past end of a page
|
||
|
|
enum { cpu_padding = 8 };
|
||
|
|
enum { mem_size = 0x10000 };
|
||
|
|
enum { page_bits = 13 };
|
||
|
|
enum { page_size = 1 << page_bits };
|
||
|
|
enum { page_count = mem_size >> page_bits };
|
||
|
|
|
||
|
|
// Game Boy Z-80 registers. NOT kept updated during emulation.
|
||
|
|
struct core_regs_t {
|
||
|
|
uint16_t bc, de, hl, fa;
|
||
|
|
};
|
||
|
|
|
||
|
|
struct registers_t {
|
||
|
|
int pc; // more than 16 bits to allow overflow detection
|
||
|
|
uint16_t sp;
|
||
|
|
|
||
|
|
struct core_regs_t rp;
|
||
|
|
};
|
||
|
|
|
||
|
|
struct cpu_state_t {
|
||
|
|
byte* code_map [page_count + 1];
|
||
|
|
int time;
|
||
|
|
};
|
||
|
|
|
||
|
|
struct Gb_Cpu {
|
||
|
|
// Base address for RST vectors, to simplify GBS player (normally 0)
|
||
|
|
addr_t rst_base;
|
||
|
|
|
||
|
|
struct registers_t r;
|
||
|
|
struct cpu_state_t* cpu_state; // points to state_ or a local copy within run()
|
||
|
|
struct cpu_state_t cpu_state_;
|
||
|
|
};
|
||
|
|
|
||
|
|
// Initializes Gb cpu
|
||
|
|
static inline void Cpu_init( struct Gb_Cpu* this )
|
||
|
|
{
|
||
|
|
this->rst_base = 0;
|
||
|
|
this->cpu_state = &this->cpu_state_;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Clears registers and map all pages to unmapped
|
||
|
|
void Cpu_reset( struct Gb_Cpu* this, void* unmapped );
|
||
|
|
|
||
|
|
// Maps code memory (memory accessed via the program counter). Start and size
|
||
|
|
// must be multiple of page_size.
|
||
|
|
void Cpu_map_code( struct Gb_Cpu* this, addr_t start, int size, void* code ) ICODE_ATTR;
|
||
|
|
|
||
|
|
// Current time.
|
||
|
|
static inline int Cpu_time( struct Gb_Cpu* this ) { return this->cpu_state->time; }
|
||
|
|
|
||
|
|
// Changes time. Must not be called during emulation.
|
||
|
|
// Should be negative, because emulation stops once it becomes >= 0.
|
||
|
|
static inline void Cpu_set_time( struct Gb_Cpu* this, int t ) { this->cpu_state->time = t; }
|
||
|
|
|
||
|
|
#define GB_CPU_PAGE( addr ) ((unsigned) (addr) >> page_bits)
|
||
|
|
|
||
|
|
#ifdef BLARGG_NONPORTABLE
|
||
|
|
#define GB_CPU_OFFSET( addr ) (addr)
|
||
|
|
#else
|
||
|
|
#define GB_CPU_OFFSET( addr ) ((addr) & (page_size - 1))
|
||
|
|
#endif
|
||
|
|
|
||
|
|
// Accesses emulated memory as CPU does
|
||
|
|
static inline uint8_t* Cpu_get_code( struct Gb_Cpu* this, addr_t addr )
|
||
|
|
{
|
||
|
|
return this->cpu_state_.code_map [GB_CPU_PAGE( addr )] + GB_CPU_OFFSET( addr );
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif
|