midcsd.cpp

// Cheap Squeak Deluxe audio module
// based on MAME sources by Aaron Giles

#include "burnint.h"
#include "m68000_intf.h"
#include "6821pia.h"
#include "dac.h"

static UINT16 dacvalue;
static UINT16 csd_status;
static INT32 csd_in_reset;
static INT32 csd_is_intialized = 0;

static void csd_porta_w(UINT16, UINT8 data)
{
	dacvalue = (data << 2) | (dacvalue & 3);
   // if (dacvalue !=0) bprintf(0, _T("%X,"), dacvalue);
    if (dacvalue == 0x02 || dacvalue == 0x03) dacvalue = 0xFE; // silly hack gets rid of pops in spyhunter when the music starts/stops
	DACWrite16Signed(0, dacvalue << 6);
}

static void csd_portb_w(UINT16, UINT8 data)
{
	dacvalue = (dacvalue & ~0x3) | (data >> 6);
   // if (dacvalue !=0) bprintf(0, _T("%X,"), dacvalue);
    if (dacvalue == 0x02 || dacvalue == 0x03) dacvalue = 0xFE; // see "silly hack", above
	DACWrite16Signed(0, dacvalue << 6);

    //if (~pia_get_ddr_b(0) & 0x30) csd_status = (data >> 4) & 3;
    UINT8 z_mask = pia_get_ddr_b(0);
    if (~z_mask & 0x10)  csd_status = (csd_status & ~1) | ((data >> 4) & 1);
    if (~z_mask & 0x20)  csd_status = (csd_status & ~2) | ((data >> 4) & 2);

}

static void csd_irq(int state)
{
	SekSetIRQLine(4, state ? CPU_IRQSTATUS_ACK : CPU_IRQSTATUS_NONE);
}

void csd_reset_write(int state)
{
	if (csd_is_intialized == 0) return;

	csd_in_reset = state;

	if (state) {
		INT32 cpu_active = SekGetActive();
		if (cpu_active == -1) SekOpen(0);
		SekReset();
		if (cpu_active == -1) SekClose();
	}
}

static void __fastcall csd_write_word(UINT32 address, UINT16 data)
{
	if ((address & 0x1fff8) == 0x18000) {
		pia_write(0, (address / 2) & 3, data & 0xff);
		return;
	}
}

static void __fastcall csd_write_byte(UINT32 address, UINT8 data)
{
	if ((address & 0x1fff8) == 0x18000) {
		pia_write(0, (address / 2) & 3, data);
		return;
	}
}

static UINT16 __fastcall csd_read_word(UINT32 address)
{
	if ((address & 0x1fff8) == 0x18000) {
		UINT8 ret = pia_read(0, (address / 2) & 3);
		return ret | (ret << 8);
	}

	return 0;
}

static UINT8 __fastcall csd_read_byte(UINT32 address)
{
	if ((address & 0x1fff8) == 0x18000) {
		return pia_read(0, (address / 2) & 3);
	}

	return 0;
}

void csd_data_write(UINT16 data)
{
	if (csd_is_intialized == 0) return;

    pia_set_input_b(0, data & 0x0f);
    pia_set_input_ca1(0, ~data & 0x10);
}

UINT8 csd_status_read()
{
	if (csd_is_intialized == 0) return 0;

	return csd_status;
}

INT32 csd_reset_status()
{
	if (csd_is_intialized == 0) return 1;

	return csd_in_reset;
}

INT32 csd_initialized()
{
	return csd_is_intialized;
}

void csd_reset()
{
	if (csd_is_intialized == 0) return;

	SekOpen(0);
	SekReset();
	DACReset();
	SekClose();

	pia_reset();

	csd_status = 0;
	csd_in_reset = 0;
	dacvalue = 0;
}

static const pia6821_interface pia_intf = {
	0, 0, 0, 0, 0, 0,
	csd_porta_w, csd_portb_w, 0, 0,
	csd_irq, csd_irq
};

void csd_init(UINT8 *rom, UINT8 *ram)
{
	SekInit(0, 0x68000);
	SekOpen(0);
	SekMapMemory(rom,			0x000000, 0x007fff, MAP_ROM);
	SekMapMemory(ram,			0x01c000, 0x01cfff, MAP_RAM);
	SekSetWriteWordHandler(0,	csd_write_word);
	SekSetWriteByteHandler(0,	csd_write_byte);
	SekSetReadWordHandler(0,	csd_read_word);
	SekSetReadByteHandler(0,	csd_read_byte);
	SekClose();

	pia_init();
	pia_config(0, PIA_ALTERNATE_ORDERING, &pia_intf);
	
	DACInit(0, 0, 1, SekTotalCycles, 8000000);
	DACSetRoute(0, 1.00, BURN_SND_ROUTE_BOTH);
    DACDCBlock(1);

	csd_is_intialized = 1;
}

void csd_exit()
{
	if (csd_is_intialized == 0) return;

	SekExit();
	pia_init();
	DACExit();
	csd_is_intialized = 0;
}

void csd_scan(INT32 nAction, INT32 *pnMin)
{
	if (csd_is_intialized == 0) return;

	if (nAction & ACB_VOLATILE)
	{
		SekScan(nAction);
		DACScan(nAction, pnMin);
		pia_scan(nAction, pnMin);

		SCAN_VAR(csd_status);
		SCAN_VAR(csd_in_reset);
		SCAN_VAR(dacvalue);
	}
}