diff options
Diffstat (limited to 'gme/Hes_Cpu.h')
-rw-r--r-- | gme/Hes_Cpu.h | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/gme/Hes_Cpu.h b/gme/Hes_Cpu.h new file mode 100644 index 00000000..9cb8b006 --- /dev/null +++ b/gme/Hes_Cpu.h @@ -0,0 +1,124 @@ +// PC Engine CPU emulator for use with HES music files + +// Game_Music_Emu 0.5.2 +#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 = LONG_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 |