cog/Frameworks/GME/gme/Z80_Cpu.h

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2013-09-28 03:24:46 +00:00
// Z80 CPU emulator
// $package
#ifndef Z80_CPU_H
#define Z80_CPU_H
#include "blargg_endian.h"
class Z80_Cpu {
public:
typedef int time_t;
typedef int addr_t;
typedef BOOST::uint8_t byte;
// Clears registers and maps all pages to unmapped
void reset( void* unmapped_write, void const* unmapped_read );
// TODO: split mapping out of CPU
// Maps memory. Start and size must be multiple of page_size.
enum { page_bits = 10 };
enum { page_size = 1 << page_bits };
void map_mem( addr_t addr, int size, void* write, void const* read );
void map_mem( addr_t addr, int size, void* read_write );
// Maps address to pointer to that byte
byte * write( addr_t addr );
byte const* read( addr_t addr );
// Time of beginning of next instruction
time_t time() const { return cpu_state->time + cpu_state->base; }
// Alter current time
void set_time( time_t t ) { cpu_state->time = t - cpu_state->base; }
void adjust_time( int delta ) { cpu_state->time += delta; }
#if BLARGG_BIG_ENDIAN
struct regs_t { byte b,c, d,e, h,l, flags,a; };
#else
struct regs_t { byte c,b, e,d, l,h, a,flags; };
#endif
BLARGG_STATIC_ASSERT( sizeof (regs_t) == 8 );
struct pairs_t { BOOST::uint16_t bc, de, hl, fa; };
// Registers are not updated until run() returns
struct registers_t {
BOOST::uint16_t pc;
BOOST::uint16_t sp;
BOOST::uint16_t ix;
BOOST::uint16_t iy;
union {
regs_t b; // b.b, b.c, b.d, b.e, b.h, b.l, b.flags, b.a
pairs_t w; // w.bc, w.de, w.hl. w.fa
};
union {
regs_t b;
pairs_t w;
} alt;
byte iff1;
byte iff2;
byte r;
byte i;
byte im;
};
//registers_t r; (below for efficiency)
// can read this far past end of memory
enum { cpu_padding = 0x100 };
// Can read this many bytes past end of a page
enum { page_padding = 4 };
void set_end_time( time_t t );
public:
Z80_Cpu();
enum { page_count = 0x10000 / page_size };
byte szpc [0x200];
time_t end_time_;
struct cpu_state_t {
byte const* read [page_count + 1];
byte * write [page_count + 1];
time_t base;
time_t time;
};
cpu_state_t* cpu_state; // points to cpu_state_ or a local copy within run()
cpu_state_t cpu_state_;
void set_page( int i, void* write, void const* read );
public:
registers_t r;
};
#if BLARGG_NONPORTABLE
#define Z80_CPU_OFFSET( addr ) (addr)
#else
#define Z80_CPU_OFFSET( addr ) ((addr) & (Z80_Cpu::page_size - 1))
#endif
inline Z80_Cpu::byte* Z80_Cpu::write( addr_t addr )
{
return cpu_state->write [(unsigned) addr >> page_bits] + Z80_CPU_OFFSET( addr );
}
inline Z80_Cpu::byte const* Z80_Cpu::read( addr_t addr )
{
return cpu_state->read [(unsigned) addr >> page_bits] + Z80_CPU_OFFSET( addr );
}
inline void Z80_Cpu::map_mem( addr_t addr, int size, void* p )
{
map_mem( addr, size, p, p );
}
inline void Z80_Cpu::set_end_time( time_t t )
{
time_t delta = cpu_state->base - t;
cpu_state->base = t;
cpu_state->time += delta;
}
#endif