140 lines
3.2 KiB
C++
140 lines
3.2 KiB
C++
// PC Engine CPU emulator for use with HES music files
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// $package
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#ifndef HES_CPU_H
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#define HES_CPU_H
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#include "blargg_common.h"
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class Hes_Cpu {
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public:
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typedef BOOST::uint8_t byte;
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typedef int time_t;
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typedef int addr_t;
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enum { future_time = INT_MAX/2 + 1 };
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void reset();
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enum { page_bits = 13 };
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enum { page_size = 1 << page_bits };
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enum { page_count = 0x10000 / page_size };
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void set_mmr( int reg, int bank, void const* code );
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byte const* get_code( addr_t );
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// NOT kept updated during emulation.
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struct registers_t {
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BOOST::uint16_t pc;
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byte a;
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byte x;
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byte y;
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byte flags;
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byte sp;
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};
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registers_t r;
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// page mapping registers
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byte mmr [page_count + 1];
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// Time of beginning of next instruction to be executed
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time_t time() const { return cpu_state->time + cpu_state->base; }
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void set_time( time_t t ) { cpu_state->time = t - cpu_state->base; }
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void adjust_time( int delta ) { cpu_state->time += delta; }
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// Clocks past end (negative if before)
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int time_past_end() const { return cpu_state->time; }
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// Time of next IRQ
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time_t irq_time() const { return irq_time_; }
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void set_irq_time( time_t );
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// Emulation stops once time >= end_time
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time_t end_time() const { return end_time_; }
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void set_end_time( time_t );
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// Subtracts t from all times
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void end_frame( time_t t );
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// Can read this many bytes past end of a page
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enum { cpu_padding = 8 };
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private:
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// noncopyable
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Hes_Cpu( const Hes_Cpu& );
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Hes_Cpu& operator = ( const Hes_Cpu& );
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// Implementation
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public:
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Hes_Cpu() { cpu_state = &cpu_state_; }
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enum { irq_inhibit_mask = 0x04 };
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struct cpu_state_t {
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byte const* code_map [page_count + 1];
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time_t base;
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int time;
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};
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cpu_state_t* cpu_state; // points to cpu_state_ or a local copy
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cpu_state_t cpu_state_;
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time_t irq_time_;
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time_t end_time_;
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private:
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void set_code_page( int, void const* );
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inline void update_end_time( time_t end, time_t irq );
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};
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#define HES_CPU_PAGE( addr ) ((unsigned) (addr) >> Hes_Cpu::page_bits)
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#if BLARGG_NONPORTABLE
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#define HES_CPU_OFFSET( addr ) (addr)
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#else
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#define HES_CPU_OFFSET( addr ) ((addr) & (Hes_Cpu::page_size - 1))
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#endif
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inline BOOST::uint8_t const* Hes_Cpu::get_code( addr_t addr )
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{
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return cpu_state_.code_map [HES_CPU_PAGE( addr )] + HES_CPU_OFFSET( addr );
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}
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inline void Hes_Cpu::update_end_time( time_t end, time_t irq )
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{
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if ( end > irq && !(r.flags & irq_inhibit_mask) )
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end = irq;
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cpu_state->time += cpu_state->base - end;
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cpu_state->base = end;
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}
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inline void Hes_Cpu::set_irq_time( time_t t )
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{
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irq_time_ = t;
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update_end_time( end_time_, t );
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}
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inline void Hes_Cpu::set_end_time( time_t t )
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{
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end_time_ = t;
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update_end_time( t, irq_time_ );
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}
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inline void Hes_Cpu::end_frame( time_t t )
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{
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assert( cpu_state == &cpu_state_ );
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cpu_state_.base -= t;
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if ( irq_time_ < future_time ) irq_time_ -= t;
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if ( end_time_ < future_time ) end_time_ -= t;
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}
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inline void Hes_Cpu::set_mmr( int reg, int bank, void const* code )
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{
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assert( (unsigned) reg <= page_count ); // allow page past end to be set
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assert( (unsigned) bank < 0x100 );
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mmr [reg] = bank;
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byte const* p = STATIC_CAST(byte const*,code) - HES_CPU_OFFSET( reg << page_bits );
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cpu_state->code_map [reg] = p;
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cpu_state_.code_map [reg] = p;
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}
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#endif
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