system.c

DC的SEGA_GG模拟器源代码

/*
    Copyright (C) 1998, 1999, 2000  Charles Mac Donald

    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
*/

#include "shared.h"


t_bitmap bitmap;
t_cart cart;                
t_snd snd;
t_input input;
FM_OPL *ym3812;


void system_init(int rate, int frequency)
{
    /* Initialize the VDP emulation */
    vdp_init();

    /* Initialize the SMS emulation */
    sms_init();

    /* Initialize the look-up tables and related data */
    render_init();

    /* Enable sound emulation if the sample rate was specified */
    audio_init(rate, frequency);

    /* Don't save SRAM by default */
    sms.save = 0;

    /* Clear emulated button state */
    memset(&input, 0, sizeof(t_input));
}

void audio_init(int rate, int frequency)
{
    /* Clear sound context */
    memset(&snd, 0, sizeof(t_snd));

    /* Reset logging data */
    snd.log = 0;
    snd.callback = NULL;

    /* Oops.. sound is disabled */
    if(!rate) return;

    /* Calculate buffer size in samples */
    snd.bufsize = (rate / frequency);

    /* Sound output */
    snd.buffer = (signed short int *)malloc(snd.bufsize * 4);
    if(!snd.buffer) return;

    /* YM3812/YM2413 sound stream */
    snd.fm_buffer = (signed short int *)malloc(snd.bufsize * 2);
    if(!snd.fm_buffer) return;

    /* SN76489 sound stream */
    snd.psg_buffer[0] = (signed short int *)malloc(snd.bufsize * 2);
    snd.psg_buffer[1] = (signed short int *)malloc(snd.bufsize * 2);
    if(!snd.psg_buffer[0] || !snd.psg_buffer[1]) return;

    /* Set up SN76489 emulation */
    SN76496_init(0, MASTER_CLOCK, 255, rate);

    /* Set up YM3812 emulation */
    ym3812 = OPLCreate(OPL_TYPE_YM3812, MASTER_CLOCK, rate);
    if(!ym3812) return;

    /* Set up YM2413 emulation */
    ym2413_init(1);

    /* Inform other functions that we can use sound */
    snd.enabled = 1;
}


void system_shutdown(void)
{
    if(snd.enabled) OPLDestroy(ym3812);
}


void system_reset(void)
{
    cpu_reset();
    vdp_reset();
    sms_reset();
    render_reset();
    LoadSRAM();
    if(snd.enabled)
    {
        OPLResetChip(ym3812);
        ym2413_reset(0);
    }
}