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// PC Engine CPU emulator for use with HES music files
// Game_Music_Emu 0.5.5
#ifndef HES_CPU_H
#define HES_CPU_H
#include "blargg_common.h"
typedef blargg_long hes_time_t; // clock cycle count
typedef unsigned hes_addr_t; // 16-bit address
enum { future_hes_time = INT_MAX / 2 + 1 };
class Hes_Cpu {
public:
typedef BOOST::uint8_t uint8_t;
void reset();
enum { page_size = 0x2000 };
enum { page_shift = 13 };
enum { page_count = 8 };
void set_mmr( int reg, int bank );
uint8_t const* get_code( hes_addr_t );
uint8_t ram [page_size];
// not kept updated during a call to run()
struct registers_t {
BOOST::uint16_t pc;
uint8_t a;
uint8_t x;
uint8_t y;
uint8_t status;
uint8_t sp;
};
registers_t r;
// page mapping registers
uint8_t mmr [page_count + 1];
// Set end_time and run CPU from current time. Returns true if any illegal
// instructions were encountered.
bool run( hes_time_t end_time );
// Time of beginning of next instruction to be executed
hes_time_t time() const { return state->time + state->base; }
void set_time( hes_time_t t ) { state->time = t - state->base; }
void adjust_time( int delta ) { state->time += delta; }
hes_time_t irq_time() const { return irq_time_; }
void set_irq_time( hes_time_t );
hes_time_t end_time() const { return end_time_; }
void set_end_time( hes_time_t );
void end_frame( hes_time_t );
// Attempt to execute instruction here results in CPU advancing time to
// lesser of irq_time() and end_time() (or end_time() if IRQs are
// disabled)
enum { idle_addr = 0x1FFF };
// Can read this many bytes past end of a page
enum { cpu_padding = 8 };
public:
Hes_Cpu() { state = &state_; }
enum { irq_inhibit = 0x04 };
private:
// noncopyable
Hes_Cpu( const Hes_Cpu& );
Hes_Cpu& operator = ( const Hes_Cpu& );
struct state_t {
uint8_t const* code_map [page_count + 1];
hes_time_t base;
blargg_long time;
};
state_t* state; // points to state_ or a local copy within run()
state_t state_;
hes_time_t irq_time_;
hes_time_t end_time_;
void set_code_page( int, void const* );
inline int update_end_time( hes_time_t end, hes_time_t irq );
};
inline BOOST::uint8_t const* Hes_Cpu::get_code( hes_addr_t addr )
{
return state->code_map [addr >> page_shift] + addr
#if !BLARGG_NONPORTABLE
% (unsigned) page_size
#endif
;
}
inline int Hes_Cpu::update_end_time( hes_time_t t, hes_time_t irq )
{
if ( irq < t && !(r.status & irq_inhibit) ) t = irq;
int delta = state->base - t;
state->base = t;
return delta;
}
inline void Hes_Cpu::set_irq_time( hes_time_t t )
{
state->time += update_end_time( end_time_, (irq_time_ = t) );
}
inline void Hes_Cpu::set_end_time( hes_time_t t )
{
state->time += update_end_time( (end_time_ = t), irq_time_ );
}
inline void Hes_Cpu::end_frame( hes_time_t t )
{
assert( state == &state_ );
state_.base -= t;
if ( irq_time_ < future_hes_time ) irq_time_ -= t;
if ( end_time_ < future_hes_time ) end_time_ -= t;
}
#endif
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