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718112a8fe
Currently none of these is being used, but eventually they will, once more code gets ported over. So it's better to have them right away and avoid editing the project file too much, only to revert that later.
122 lines
2.9 KiB
C++
122 lines
2.9 KiB
C++
// PC Engine CPU emulator for use with HES music files
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// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
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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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typedef blargg_long hes_time_t; // clock cycle count
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typedef unsigned hes_addr_t; // 16-bit address
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enum { future_hes_time = INT_MAX / 2 + 1 };
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class Hes_Cpu {
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public:
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void reset();
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enum { page_size = 0x2000 };
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enum { page_shift = 13 };
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enum { page_count = 8 };
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void set_mmr( int reg, int bank );
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uint8_t const* get_code( hes_addr_t );
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uint8_t ram [page_size];
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// not kept updated during a call to run()
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struct registers_t {
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uint16_t pc;
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uint8_t a;
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uint8_t x;
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uint8_t y;
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uint8_t status;
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uint8_t sp;
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};
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registers_t r;
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// page mapping registers
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uint8_t mmr [page_count + 1];
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// Set end_time and run CPU from current time. Returns true if any illegal
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// instructions were encountered.
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bool run( hes_time_t end_time );
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// Time of beginning of next instruction to be executed
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hes_time_t time() const { return state->time + state->base; }
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void set_time( hes_time_t t ) { state->time = t - state->base; }
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void adjust_time( int delta ) { state->time += delta; }
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hes_time_t irq_time() const { return irq_time_; }
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void set_irq_time( hes_time_t );
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hes_time_t end_time() const { return end_time_; }
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void set_end_time( hes_time_t );
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void end_frame( hes_time_t );
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// Attempt to execute instruction here results in CPU advancing time to
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// lesser of irq_time() and end_time() (or end_time() if IRQs are
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// disabled)
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enum { idle_addr = 0x1FFF };
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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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public:
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Hes_Cpu() { state = &state_; }
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enum { irq_inhibit = 0x04 };
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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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struct state_t {
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uint8_t const* code_map [page_count + 1];
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hes_time_t base;
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blargg_long time;
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};
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state_t* state; // points to state_ or a local copy within run()
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state_t state_;
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hes_time_t irq_time_;
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hes_time_t end_time_;
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void set_code_page( int, void const* );
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inline int update_end_time( hes_time_t end, hes_time_t irq );
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};
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inline uint8_t const* Hes_Cpu::get_code( hes_addr_t addr )
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{
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return state->code_map [addr >> page_shift] + addr
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#if !BLARGG_NONPORTABLE
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% (unsigned) page_size
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#endif
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;
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}
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inline int Hes_Cpu::update_end_time( hes_time_t t, hes_time_t irq )
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{
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if ( irq < t && !(r.status & irq_inhibit) ) t = irq;
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int delta = state->base - t;
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state->base = t;
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return delta;
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}
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inline void Hes_Cpu::set_irq_time( hes_time_t t )
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{
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state->time += update_end_time( end_time_, (irq_time_ = t) );
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}
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inline void Hes_Cpu::set_end_time( hes_time_t t )
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{
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state->time += update_end_time( (end_time_ = t), irq_time_ );
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}
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inline void Hes_Cpu::end_frame( hes_time_t t )
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{
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assert( state == &state_ );
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state_.base -= t;
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if ( irq_time_ < future_hes_time ) irq_time_ -= t;
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if ( end_time_ < future_hes_time ) end_time_ -= t;
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}
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#endif
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