a1145a1d04
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30284 a1c6a512-1295-4272-9138-f99709370657
95 lines
2.1 KiB
C
95 lines
2.1 KiB
C
// PC Engine CPU emulator for use with HES music files
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// Game_Music_Emu 0.5.2
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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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struct Hes_Emu;
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enum { future_hes_time = LONG_MAX / 2 + 1 };
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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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// 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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enum { irq_inhibit = 0x04 };
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// Cpu state
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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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// Cpu registers
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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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struct Hes_Cpu {
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struct registers_t r;
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hes_time_t irq_time;
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hes_time_t end_time;
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struct state_t* state; // points to state_ or a local copy within run()
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struct state_t state_;
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// page mapping registers
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uint8_t mmr [page_count + 1];
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uint8_t ram [page_size];
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};
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// Init cpu state
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void Cpu_init( struct Hes_Cpu* this );
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// Reset hes cpu
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void Cpu_reset( struct Hes_Cpu* this );
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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 Cpu_run( struct Hes_Emu* this, hes_time_t end_time );
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void Cpu_set_mmr( struct Hes_Emu* this, int reg, int bank );
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// Time of ning of next instruction to be executed
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static inline hes_time_t Cpu_time( struct Hes_Cpu* this )
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{
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return this->state->time + this->state->base;
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}
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static inline uint8_t const* Cpu_get_code( struct Hes_Cpu* this, hes_addr_t addr )
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{
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return this->state->code_map [addr >> page_shift] + addr
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#if !defined (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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static inline int Cpu_update_end_time( struct Hes_Cpu* this, uint8_t reg_status, hes_time_t t, hes_time_t irq )
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{
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if ( irq < t && !(reg_status & irq_inhibit) ) t = irq;
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int delta = this->state->base - t;
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this->state->base = t;
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return delta;
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}
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#endif
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