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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.
81 lines
2 KiB
C++
81 lines
2 KiB
C++
// Atari 6502 CPU emulator
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// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
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#ifndef SAP_CPU_H
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#define SAP_CPU_H
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#include "blargg_common.h"
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typedef blargg_long sap_time_t; // clock cycle count
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typedef unsigned sap_addr_t; // 16-bit address
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enum { future_sap_time = INT_MAX / 2 + 1 };
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class Sap_Cpu {
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public:
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// Clear all registers and keep pointer to 64K memory passed in
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void reset( void* mem_64k );
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// Run until specified time is reached. Returns true if suspicious/unsupported
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// instruction was encountered at any point during run.
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bool run( sap_time_t end_time );
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// Registers are not updated until run() returns (except I flag in status)
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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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enum { idle_addr = 0xFEFF };
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// Time of beginning of next instruction to be executed
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sap_time_t time() const { return state->time + state->base; }
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void set_time( sap_time_t t ) { state->time = t - state->base; }
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void adjust_time( int delta ) { state->time += delta; }
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sap_time_t irq_time() const { return irq_time_; }
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void set_irq_time( sap_time_t );
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sap_time_t end_time() const { return end_time_; }
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void set_end_time( sap_time_t );
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public:
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Sap_Cpu() { state = &state_; }
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enum { irq_inhibit = 0x04 };
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private:
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struct state_t {
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sap_time_t base;
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sap_time_t 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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sap_time_t irq_time_;
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sap_time_t end_time_;
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uint8_t* mem;
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inline sap_time_t update_end_time( sap_time_t end, sap_time_t irq );
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};
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inline sap_time_t Sap_Cpu::update_end_time( sap_time_t t, sap_time_t irq )
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{
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if ( irq < t && !(r.status & irq_inhibit) ) t = irq;
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sap_time_t 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 Sap_Cpu::set_irq_time( sap_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 Sap_Cpu::set_end_time( sap_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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#endif
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