/*  gngeo, a neogeo emulator
 *  Copyright (C) 2001 Peponas Mathieu
 * 
 *  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 Library 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. 
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <unistd.h>
#include <sys/time.h>
#include <math.h>
#include "SDL.h"
#include "frame_skip.h"
#include "messages.h"
#include "emu.h"
#include "conf.h"


#ifndef uclock_t
#define uclock_t Uint32
#endif

#define TICKS_PER_SEC 1000000UL
//#define CPU_FPS 60
static int CPU_FPS=60;
static uclock_t F;

#define MAX_FRAMESKIP 10


static char init_frame_skip = 1;
char skip_next_frame = 0;
static struct timeval init_tv = { 0, 0 };
uclock_t bench;

uclock_t get_ticks(void)
{
    struct timeval tv;

    gettimeofday(&tv, 0);
    if (init_tv.tv_sec == 0)
	init_tv = tv;
    return (tv.tv_sec - init_tv.tv_sec) * TICKS_PER_SEC + tv.tv_usec -
	init_tv.tv_usec;


}

void reset_frame_skip(void)
{
    static Uint8 init=0;

    if (!init) {
	    autoframeskip=CF_BOOL(cf_get_item_by_name("autoframeskip"));
	    show_fps=CF_BOOL(cf_get_item_by_name("showfps"));
	    sleep_idle=CF_BOOL(cf_get_item_by_name("sleepidle"));
	    init=1;
    }
    init_tv.tv_usec = 0;
    init_tv.tv_sec = 0;
    skip_next_frame = 0;
    init_frame_skip = 1;
    if (conf.pal)
	CPU_FPS=50;
    F = (uclock_t) ((double) TICKS_PER_SEC / CPU_FPS);
}



int frame_skip(int init)
{
    static int f2skip;
    static uclock_t sec = 0;
    static uclock_t rfd;
    static uclock_t target;
    static int nbFrame = 0;
    static int totalFrame = 0;
    static int skpFrm = 0;

    if (init_frame_skip) {
	init_frame_skip = 0;
	target = get_ticks();
	bench=(CF_BOOL(cf_get_item_by_name("bench"))?get_ticks():0);
	    
	nbFrame = 0;
	//f2skip=0;
	//skpFrm=0;
	sec = 0;
	return 0;
    }

    target += F;
    if (f2skip > 0) {
	f2skip--;
	skpFrm++;
	return 1;
    } else
	skpFrm = 0;


    rfd = get_ticks();

    if (autoframeskip) {
	if (rfd < target && f2skip == 0)
	    while (get_ticks() < target) {
		if (sleep_idle) {
		    usleep(10);
		}
	} else {
	    f2skip = (rfd - target) / (double) F;
	    if (f2skip > MAX_FRAMESKIP) {
		f2skip = MAX_FRAMESKIP;
		reset_frame_skip();
	    }
	    // printf("Skip %d frame(s) %lu %lu\n",f2skip,target,rfd);
	}
    }

    nbFrame++;
    if(bench && totalFrame++>=5000) {
	    printf("average fps=%f \n",(TICKS_PER_SEC*5000.0/(get_ticks()-bench)));
	    exit(0);
    }
    if (get_ticks() - sec >= TICKS_PER_SEC) {
	//printf("%d\n",nbFrame);
	if (show_fps)
	    sprintf(fps_str, "%2d", nbFrame-1);
	nbFrame = 0;
	sec = get_ticks();
    }
    return 0;
}