cpu.c

日本的手持pda源码.wince下使用,完全开源

/*
 *  PocketGnuboy - GameBoy emulator for PocketPC
 *  Copyright (C) 2003  Y.Nagamidori
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 *  based on gnuboy 1.0.3
 *  Copyright (C) 2000-2001 Laguna and Gilgamesh
 */

#include "defs.h"
#include "regs.h"
#include "hw.h"
#include "cpu.h"
#include "mem.h"
#include "fastmem.h"
#include "cpuregs.h"
#include "cpucore.h"

struct cpu cpu;

byte Z80toGB[256], GBtoZ80[256];

void cpu_reset()
{
	int i;

	cpu.speed = 0;
	cpu.halt = 0;
	cpu.div = 0;
	cpu.tim = 0;
	cpu.lcdc = 40;

	cpu.tac_speed = 0;
	cpu.tac_start = 0;

	IME = 0;
	
	xPC = 0x0100;
	xSP = 0xFFFE;
	xAF = 0x01B0;
	xBC = 0x0013;
	xDE = 0x00D8;
	xHL = 0x014D;
	
	if (hw.cgb) A = 0x11;
	if (hw.gba) B = 0x01;

	for (i = 0; i < 256; i++){
		Z80toGB[i] = ((i & 0x40) ? 0x80 : 0) |
					((i & 0x10) ? 0x20 : 0) |
					((i & 0x02) ? 0x40 : 0) |
					((i & 0x01) ? 0x10 : 0);
		GBtoZ80[i] = ((i & 0x80) ? 0x40 : 0) |
					((i & 0x40) ? 0x02 : 0) |
					((i & 0x20) ? 0x10 : 0) |
					((i & 0x10) ? 0x01 : 0);
	}
}

void div_advance()
{
	if (cpu.div >= 128)
	{
		R_DIV += (cpu.div >> 7);
		cpu.div &= 0xff;
	}
}

#define timer_advance(cnt) \
{ \
	if (cpu.tac_start) \
	{ \
		cpu.tim += (cnt << cpu.tac_speed); \
		if (cpu.tim >= 512) \
		{ \
			int tima;	 \
			tima = R_TIMA + (cpu.tim >> 9); \
			cpu.tim &= 0x1ff; \
			if (tima >= 256) \
			{ \
				hw_interrupt(IF_TIMER); \
				while (tima >= 256) \
					tima = tima - 256 + R_TMA; \
			} \
			R_TIMA = tima; \
		} \
	} \
}

#define lcdc_advance(cnt)\
{\
	cpu.lcdc -= cnt;\
	if (cpu.lcdc <= 0) lcdc_trans();\
}\

#define sound_advance(cnt)\
{\
	cpu.snd += cnt;\
}\

INLINE int cpu_idle()
{
	int cnt, max;
	
	if (R_IF & R_IE)
	{
		cpu.halt = 0;
		return 0;
	}

	max = cpu.lcdc << cpu.speed;
	
	/* If timer interrupt cannot happen, this is very simple! */
	if (!((R_IE & IF_TIMER) && cpu.tac_start))
		cnt = max;
	else
	{
		/* Figure out when the next timer interrupt will happen */
		cnt = (511 - cpu.tim + (1<<cpu.tac_speed)) >> cpu.tac_speed;
		cnt += (255 - R_TIMA) << (9 - cpu.tac_speed);

		if (max < cnt)
			cnt = max;
	}

	cpu.div += (cnt);
	timer_advance(cnt);
	cnt >>= cpu.speed;
	lcdc_advance(cnt);
	sound_advance(cnt);
	return cnt;
}

INLINE void cpu_interrupt()
{
	PRE_INT;
	switch (IF & IE)
	{
	case 0x01: case 0x03: case 0x05: case 0x07:
	case 0x09: case 0x0B: case 0x0D: case 0x0F:
	case 0x11: case 0x13: case 0x15: case 0x17:
	case 0x19: case 0x1B: case 0x1D: case 0x1F:
		THROW_INT(0); break;
	case 0x02: case 0x06: case 0x0A: case 0x0E:
	case 0x12: case 0x16: case 0x1A: case 0x1E:
		THROW_INT(1); break;
	case 0x04: case 0x0C: case 0x14: case 0x1C:
		THROW_INT(2); break;
	case 0x08: case 0x18:
		THROW_INT(3); break;
	case 0x10:
		THROW_INT(4); break;
	}
}

void cpu_emulate()
{
	byte op, cbop;
	int clen;
	union reg acc = {0};
	byte b;

	cpu.emulate = 1;
	while (cpu.emulate)
	{
		if (cpu.halt && IME)
		{
			if (cpu_idle())
				continue;
		}

		if (IME && (IF & IE))
			cpu_interrupt();

		op = FETCH;
		clen = cycles_table[op];

		switch(op)
		{
#include "cpucodes.h"		
		default:
			//__assume(0);
			return;
		}

		cpu.div += clen;
		timer_advance(clen);
		clen >>= cpu.speed;
		lcdc_advance(clen);
		sound_advance(clen);
	}
}