mirror of
https://github.com/ZDoom/gzdoom-gles.git
synced 2024-11-16 17:41:19 +00:00
81 lines
2 KiB
C++
81 lines
2 KiB
C++
// Atari 6502 CPU emulator
|
|
|
|
// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
|
|
#ifndef SAP_CPU_H
|
|
#define SAP_CPU_H
|
|
|
|
#include "blargg_common.h"
|
|
|
|
typedef blargg_long sap_time_t; // clock cycle count
|
|
typedef unsigned sap_addr_t; // 16-bit address
|
|
enum { future_sap_time = INT_MAX / 2 + 1 };
|
|
|
|
class Sap_Cpu {
|
|
public:
|
|
// Clear all registers and keep pointer to 64K memory passed in
|
|
void reset( void* mem_64k );
|
|
|
|
// Run until specified time is reached. Returns true if suspicious/unsupported
|
|
// instruction was encountered at any point during run.
|
|
bool run( sap_time_t end_time );
|
|
|
|
// Registers are not updated until run() returns (except I flag in status)
|
|
struct registers_t {
|
|
uint16_t pc;
|
|
uint8_t a;
|
|
uint8_t x;
|
|
uint8_t y;
|
|
uint8_t status;
|
|
uint8_t sp;
|
|
};
|
|
registers_t r;
|
|
|
|
enum { idle_addr = 0xFEFF };
|
|
|
|
// Time of beginning of next instruction to be executed
|
|
sap_time_t time() const { return state->time + state->base; }
|
|
void set_time( sap_time_t t ) { state->time = t - state->base; }
|
|
void adjust_time( int delta ) { state->time += delta; }
|
|
|
|
sap_time_t irq_time() const { return irq_time_; }
|
|
void set_irq_time( sap_time_t );
|
|
|
|
sap_time_t end_time() const { return end_time_; }
|
|
void set_end_time( sap_time_t );
|
|
|
|
public:
|
|
Sap_Cpu() { state = &state_; }
|
|
enum { irq_inhibit = 0x04 };
|
|
private:
|
|
struct state_t {
|
|
sap_time_t base;
|
|
sap_time_t time;
|
|
};
|
|
state_t* state; // points to state_ or a local copy within run()
|
|
state_t state_;
|
|
sap_time_t irq_time_;
|
|
sap_time_t end_time_;
|
|
uint8_t* mem;
|
|
|
|
inline sap_time_t update_end_time( sap_time_t end, sap_time_t irq );
|
|
};
|
|
|
|
inline sap_time_t Sap_Cpu::update_end_time( sap_time_t t, sap_time_t irq )
|
|
{
|
|
if ( irq < t && !(r.status & irq_inhibit) ) t = irq;
|
|
sap_time_t delta = state->base - t;
|
|
state->base = t;
|
|
return delta;
|
|
}
|
|
|
|
inline void Sap_Cpu::set_irq_time( sap_time_t t )
|
|
{
|
|
state->time += update_end_time( end_time_, (irq_time_ = t) );
|
|
}
|
|
|
|
inline void Sap_Cpu::set_end_time( sap_time_t t )
|
|
{
|
|
state->time += update_end_time( (end_time_ = t), irq_time_ );
|
|
}
|
|
|
|
#endif
|