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https://github.com/ZDoom/qzdoom.git
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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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