/* Hey EMACS -*- linux-c -*- */
/* $Id: m68k.c 2733 2007-12-21 05:33:19Z kevinkofler $ */

/*  TiEmu - Tiemu Is an EMUlator
 *
 *  Copyright (c) 2000-2001, Thomas Corvazier, Romain Lievin
 *  Copyright (c) 2001-2003, Romain Lievin
 *  Copyright (c) 2003, Julien Blache
 *  Copyright (c) 2004, Romain Liévin
 *  Copyright (c) 2005-2007, Romain Liévin, Kevin Kofler
 *
 *  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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
 */

/*
    M68K management (wrapper for the UAE engine)
*/

#include <stdlib.h>

#include "libuae.h"
#include "ti68k_def.h"
#include "ti68k_err.h"
#include "mem.h"
#include "hw.h"
#include "hwprot.h"
#include "bkpts.h"
#include "images.h"
#include "handles.h"
#include "flash.h"
#include "dbus.h"
#include "gscales.h"
#ifndef NO_SOUND
#include "ports.h"
#include "stream.h"
#include "engine.h"
#include "gettimeofday.h"
#endif

int pending_ints;

int hw_m68k_init(void)
{
    // init breakpoints
    ti68k_bkpt_clear_address();
	ti68k_bkpt_clear_exception();
	ti68k_bkpt_clear_pgmentry();
    bkpts.mode = bkpts.type = bkpts.id = 0;

    // set trap on illegal instruction
    ti68k_bkpt_add_exception(4);

    // init instruction logging
    logger.pclog_size = 11;
    logger.pclog_buf = (uint32_t *)malloc(logger.pclog_size * sizeof(uint32_t));
    if(logger.pclog_buf == NULL)
        return ERR_MALLOC;
    logger.pclog_ptr = 0;

    init_m68k();

    return 0;
}

int hw_m68k_reset(void)
{
	// retrieve SSP & PC values for boot
	find_ssp_and_pc(&tihw.initial_ssp, &tihw.initial_pc);

	// and reset
    m68k_reset();

	pending_ints = 0;

    return 0;
}

int hw_m68k_exit(void)
{
    ti68k_bkpt_clear_address();
	ti68k_bkpt_clear_exception();

    free(logger.pclog_buf);

    return 0;
}

// UAE does not implement interrupt priority and pending interrupts
// I re-implement it as replacement of Interrupt()
void Interrupt2(int nr)
{
	if((nr > regs.intmask) || (nr == 7))
	{
		Interrupt(nr);
		pending_ints &= ~(1 << nr);	// clr pending int
	}
}

void hw_m68k_irq(int n)
{
	set_special(SPCFLAG_INT);
    currIntLev = n;				// unused, used for compat with old Interrupt()

	pending_ints |= (1 << n);	// set pending int
}

// parse pending ints for one to raise (up to low prority order)
#define GET_INT_LVL(level)	\
	{ \
		int mask = 0x80;	\
			for (level = 7; level; level--, mask >>= 1)	\
				if (pending_ints & mask)	\
					break;	\
	}

/* Replace UAE's M68000_run() */

/*
	Returns cycle count.
*/
static unsigned int cycles = 0;
unsigned int hw_m68k_get_cycle_count(int reset)
{
	if(reset) cycles = 0;
	return cycles;
}

/*
  Do 'n' instructions (up to 'maxcycles', unless set to 0). 
  Returned value:
  - 1 if breakpoint has been encountered,
  - 2 if trace,
  - 0 otherwise.
*/
int hw_m68k_run(int n, unsigned maxcycles)
{
    int i=n;
    GList *l = NULL;
    unsigned int cycles_at_start = cycles;
#ifndef NO_SOUND
    static unsigned int cycles_sound_441 = 0;
    static struct timeval last_sound_event = {0, 0};
    static unsigned int usecs_sound_441 = 0;
#endif

	for(i = 0; i < n && (!maxcycles || cycles - cycles_at_start < maxcycles); i++)
	{
		uae_u32 opcode;
		unsigned int insn_cycles;
#ifndef NO_SOUND
		unsigned cutoff;
		int low_power_mode = 0;
#endif

		// refresh hardware
		do_cycles();

		// OSC1 stopped ? Refresh hardware and wake-up on interrupt. No opcode execution.
		if ((regs.spcflags & SPCFLAG_STOP))
	    {
			if(pending_ints)
			{
				int level;
				GET_INT_LVL(level);

				// wake-up on int level 6 (ON key) or level 1..5
				if ((pending_ints & (tihw.io[5] << 1)) || (level == 6))
				{
					Interrupt2(level);
					regs.stopped = 0;
					regs.spcflags &= ~SPCFLAG_STOP;
				}
			}

			cycles += 4; // cycle count for hw_m68k_run loop
			cycle_count += 4; // cycle count for hw.c timers
			tihw.lcd_tick += 4; // used by grayscale for time plane exposure

#ifdef NO_SOUND
			continue;
#else
			low_power_mode = 1;
			insn_cycles = 4;
			goto check_sound;
#endif
	    }		

		// search for code breakpoint
        if(((l = bkpts.code) != NULL) && !(regs.spcflags & SPCFLAG_DBSKIP)
           && !(regs.spcflags & SPCFLAG_BRK))
        {
            bkpts.id = 0;
            while(l)
            {
                if(BKPT_ADDR(GPOINTER_TO_INT(l->data)) == (int)m68k_getpc())
                {
					if(BKPT_IS_TMP(GPOINTER_TO_INT(l->data)))
						bkpts.code = g_list_remove(bkpts.code, l->data);

                    bkpts.type = BK_TYPE_CODE;
		            //regs.spcflags |= SPCFLAG_BRK;
                    return 1;
                }

                bkpts.id++;
                l = g_list_next(l);
            }
        }

		// search for pgrm entry breakpoint
		if((bkpts.pgmentry != NULL) && !(regs.spcflags & SPCFLAG_DBSKIP)
		   && !(regs.spcflags & SPCFLAG_BRK))
		{
			uint16_t handle = GPOINTER_TO_INT(bkpts.pgmentry->data) >> 16;
			uint16_t offset = GPOINTER_TO_INT(bkpts.pgmentry->data) & 0xffff;
			bkpts.id = 0;

			if(heap_deref(handle)+offset == (int)m68k_getpc())
			{
				bkpts.type = BK_TYPE_PGMENTRY;
				return DBG_BREAK;
			}
		}

        // store PC in the log buffer
        if(logger.pclog_size > 1)
        {
            logger.pclog_buf[logger.pclog_ptr++] = m68k_getpc();
            if (logger.pclog_ptr >= logger.pclog_size) logger.pclog_ptr = 0;
        }

		// hardware protection
		if(params.hw_protect)
		{
			if((bkpts.id = hwp_fetch(m68k_getpc())))
			{
				bkpts.type = BK_TYPE_PROTECT;
				return DBG_HWPV;
			}
		}

		// search for next opcode and execute it
		opcode = get_iword_prefetch (0);
		insn_cycles = (*cpufunctbl[opcode])(opcode) * 2; // increments PC automatically now
		cycles += insn_cycles; // cycle count for hw_m68k_run loop
		cycle_count += insn_cycles; // cycle count for hw.c timers
		tihw.lcd_tick += insn_cycles; // used by grayscale for time plane exposure

		// HW2/3 grayscales management
		lcd_hook_hw2(0);

#ifndef NO_SOUND
		// Sound emulation
		check_sound:
		if (audio_isactive)
		{
			cycles_sound_441 += insn_cycles * 441;
			cutoff = params.restricted
			         // num_cycles_per_loop / (ENGINE_TIME_LIMIT * (44100/441) / 1000)
			         ? (unsigned) engine_num_cycles_per_loop()
			            / ((unsigned) ENGINE_TIME_LIMIT / 10u)
			         // check every 100 cycles
			         : 44100u;
			if (cycles_sound_441 >= cutoff)
			{
				// keep excess cycles so we don't accumulate delays
				cycles_sound_441 -= cutoff;
				if (params.restricted || !last_sound_event.tv_sec)
				{
					// for seamless switching to !params.restricted
					// or when we don't have a last_sound_event yet
					gettimeofday(&last_sound_event, NULL);
					usecs_sound_441 = 0u;
				}
				else
				{
					static struct timeval this_sound_event = {0, 0};
					gettimeofday(&this_sound_event, NULL);
					usecs_sound_441 += (this_sound_event.tv_sec - last_sound_event.tv_sec) * 441000000u
					                   + (this_sound_event.tv_usec - last_sound_event.tv_usec) * 441u;
					last_sound_event = this_sound_event;
					if (usecs_sound_441 < 10000u)
						goto skip_sound_processing;
					// keep excess usecs so we don't accumulate delays
					usecs_sound_441 -= 10000u;
				}
				// push amplitudes now
				// We should do this only if(io_bit_tst(0x0c,6))
				// (direct access), but unfortunately Nebulus
				// doesn't bother setting that mode.
				// bit 1 = left channel, bit 0 = right channel
				// value 1 = low, value 0 = high
				stream_push_amplitudes((char)(io_bit_tst(0x0e,1) ? 0 : 127),
				                (char)(io_bit_tst(0x0e,0) ? 0 : 127));
			}
			skip_sound_processing: ;
		}
		else
		{
			cycles_sound_441 = 0u;
			last_sound_event.tv_sec = last_sound_event.tv_usec = 0;
			usecs_sound_441 = 0u;
		}
		if (low_power_mode)
			continue;
#endif

#ifndef NO_GDB
		extern void sim_trace_one(int);
		if (trace)
			sim_trace_one(m68k_getpc());
#endif

		if (recfile_flag)
			recfile();

		// process (pending) interrupts
		if(pending_ints)
		{
			int level;
			GET_INT_LVL(level);

			Interrupt2 (level);
			regs.stopped = 0;
			//regs.spcflags &= ~SPCFLAG_STOP;
		}

		// management of special flags
        if(regs.spcflags) 
	    {
    	    if(regs.spcflags & SPCFLAG_ADRERR) 
	        {
	            Exception(3,0);
				unset_special(SPCFLAG_ADRERR);
	        }
	  
	        if (regs.spcflags & SPCFLAG_DOTRACE) 
	        {
	            Exception(9,0);
	        }
	      
	        if (regs.spcflags & SPCFLAG_TRACE) 
	        {
				unset_special(SPCFLAG_TRACE);
			}

	        if (regs.spcflags & SPCFLAG_BRK) 
	        {		
				unset_special(SPCFLAG_BRK);
				return DBG_BREAK;
	        }

	        if(regs.spcflags & SPCFLAG_DBTRACE) 
	        {
				unset_special(SPCFLAG_DBTRACE);
				return DBG_TRACE;
	        }

            if(regs.spcflags & SPCFLAG_DBSKIP)
			{
                unset_special(SPCFLAG_DBSKIP);
			}
	    }
	}

	return 0;
}
