src/hardware/gameblaster.cpp

/*
 *  Copyright (C) 2002-2020  The DOSBox Team
 *
 *  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.
 */

#include "dosbox.h"
#include "inout.h"
#include "mixer.h"
#include "mem.h"
#include "hardware.h"
#include "setup.h"
#include "support.h"
#include "pic.h"
#include <cstring>
#include <math.h>

#include "mame/emu.h"
#include "mame/saa1099.h"

#define MASTER_CLOCK 7159090

//My mixer channel
static MixerChannel * cms_chan;
//Timer to disable the channel after a while
static Bit32u lastWriteTicks;
static Bit32u cmsBase;
static saa1099_device* device[2];

static void write_cms(Bitu port, Bitu val, Bitu /* iolen */) {
        if(cms_chan && (!cms_chan->enabled)) cms_chan->Enable(true);
        lastWriteTicks = (Bit32u)PIC_Ticks;
        switch ( port - cmsBase ) {
        case 1:
                device[0]->control_w(0, 0, (u8)val);
                break;
        case 0:
                device[0]->data_w(0, 0, (u8)val);
                break;
        case 3:
                device[1]->control_w(0, 0, (u8)val);
                break;
        case 2:
                device[1]->data_w(0, 0, (u8)val);
                break;
        }
}

static void CMS_CallBack(Bitu len) {
        enum {
                BUFFER_SIZE = 2048
        };

        if ( len > BUFFER_SIZE )
                return;

        if ( cms_chan ) {

                //Have there been 10 seconds of no commands, disable channel
                if ( lastWriteTicks + 10000 < PIC_Ticks ) {
                        cms_chan->Enable( false );
                        return;
                }
                Bit32s result[BUFFER_SIZE][2];
                Bit16s work[2][BUFFER_SIZE];
                Bit16s* buffers[2] = { work[0], work[1] };
                device_sound_interface::sound_stream stream;
                device[0]->sound_stream_update(stream, 0, buffers, (int)len);
                for (Bitu i = 0; i < len; i++) {
                        result[i][0] = work[0][i];
                        result[i][1] = work[1][i];
                }
                device[1]->sound_stream_update(stream, 0, buffers, (int)len);
                for (Bitu i = 0; i < len; i++) {
                        result[i][0] += work[0][i];
                        result[i][1] += work[1][i];
                }
                cms_chan->AddSamples_s32( len, result[0] );
        }
}

// The Gameblaster detection
static Bit8u cms_detect_register = 0xff;

static void write_cms_detect(Bitu port, Bitu val, Bitu /* iolen */) {
        switch ( port - cmsBase ) {
        case 0x6:
        case 0x7:
                cms_detect_register = (Bit8u)val;
                break;
        }
}

static Bitu read_cms_detect(Bitu port, Bitu /* iolen */) {
        Bit8u retval = 0xff;
        switch ( port - cmsBase ) {
        case 0x4:
                retval = 0x7f;
                break;
        case 0xa:
        case 0xb:
                retval = cms_detect_register;
                break;
        }
        return retval;
}


class CMS:public Module_base {
private:
        IO_WriteHandleObject WriteHandler;
        IO_WriteHandleObject DetWriteHandler;
        IO_ReadHandleObject DetReadHandler;
        MixerObject MixerChan;

public:
        CMS(Section* configuration):Module_base(configuration) {
                Section_prop * section = static_cast<Section_prop *>(configuration);
                Bitu sampleRate = (Bitu)section->Get_int( "oplrate" );
                cmsBase = (Bit32u)section->Get_hex("sbbase");
                WriteHandler.Install( cmsBase, write_cms, IO_MB, 4 );

                // A standalone Gameblaster has a magic chip on it which is
                // sometimes used for detection.
                const char * sbtype=section->Get_string("sbtype");
                if (!strcasecmp(sbtype,"gb")) {
                        DetWriteHandler.Install( cmsBase + 4, write_cms_detect, IO_MB, 12 );
                        DetReadHandler.Install(cmsBase,read_cms_detect,IO_MB,16);
                }

                /* Register the Mixer CallBack */
                cms_chan = MixerChan.Install(CMS_CallBack,sampleRate,"CMS");
        
                lastWriteTicks = (Bit32u)PIC_Ticks;

#if 0 // unused?
                Bit32u freq = 7159000;          //14318180 isa clock / 2
#endif

                machine_config config;
                device[0] = new saa1099_device(config, "", 0, 7159090);
                device[1] = new saa1099_device(config, "", 0, 7159090);

                device[0]->device_start();
                device[1]->device_start();
        }

        ~CMS() {
                cms_chan = 0;
                delete device[0];
                delete device[1];
        }
};


static CMS* test = NULL;
   
void CMS_Init(Section* sec) {
    if (test == NULL)
        test = new CMS(sec);
}
void CMS_ShutDown(Section* sec) {
    (void)sec;//UNUSED
    if (test) {
        delete test;
        test = NULL;
    }
}

// save state support
void POD_Save_Gameblaster( std::ostream& stream )
{
        const char pod_name[32] = "CMS";

    if( stream.fail() ) return;
    if( !test ) return;
    if( !cms_chan ) return;

    WRITE_POD( &pod_name, pod_name );

    //*******************************************
    //*******************************************
    //*******************************************

    // - pure data
    WRITE_POD( &lastWriteTicks, lastWriteTicks );
    WRITE_POD( &cmsBase, cmsBase );
    WRITE_POD( &cms_detect_register, cms_detect_register );

    //************************************************
    //************************************************
    //************************************************

    for (int i=0; i<2; i++) {
        device[i]->SaveState(stream);
    }

    cms_chan->SaveState(stream);
}


void POD_Load_Gameblaster( std::istream& stream )
{
        char pod_name[32] = {0};

        if( stream.fail() ) return;
        if( !test ) return;
        if( !cms_chan ) return;


        // error checking
        READ_POD( &pod_name, pod_name );
        if( strcmp( pod_name, "CMS" ) ) {
                stream.clear( std::istream::failbit | std::istream::badbit );
                return;
        }

        //*******************************************
        //*******************************************
        //*******************************************

    // - pure data
    READ_POD( &lastWriteTicks, lastWriteTicks );
    READ_POD( &cmsBase, cmsBase );
    READ_POD( &cms_detect_register, cms_detect_register );

        //************************************************
        //************************************************
        //************************************************

    for (int i=0; i<2; i++) {
        device[i]->LoadState(stream);
   }

        cms_chan->LoadState(stream);
}