86Box/src/sound/snd_opl.c

/*
 * 86Box	A hypervisor and IBM PC system emulator that specializes in
 *		running old operating systems and software designed for IBM
 *		PC systems and compatibles from 1981 through fairly recent
 *		system designs based on the PCI bus.
 *
 *		This file is part of the 86Box distribution.
 *
 *		Interface to the actual OPL emulator.
 *
 * TODO:	Finish re-working this into a device_t, which requires a
 *		poll-like function for "update" so the sound card can call
 *		that and get a buffer-full of sample data.
 *
 * Authors:	Fred N. van Kempen, <decwiz@yahoo.com>
 *		Miran Grca, <mgrca8@gmail.com>
 *
 *		Copyright 2017-2020 Fred N. van Kempen.
 *		Copyright 2016-2020 Miran Grca.
 */
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#define HAVE_STDARG_H
#include <86box/86box.h>
#include <86box/timer.h>
#include "cpu.h"
#include <86box/io.h>
#include <86box/sound.h>
#include <86box/snd_opl.h>
#include <86box/snd_opl_nuked.h>


enum {
    FLAG_CYCLES = 0x02,
    FLAG_OPL3 = 0x01
};

enum {
    STAT_TMR_OVER = 0x60,
    STAT_TMR1_OVER = 0x40,
    STAT_TMR2_OVER = 0x20,
    STAT_TMR_ANY = 0x80
};

enum {
    CTRL_RESET   = 0x80,
    CTRL_TMR_MASK = 0x60,
    CTRL_TMR1_MASK = 0x40,
    CTRL_TMR2_MASK = 0x20,
    CTRL_TMR2_START = 0x02,
    CTRL_TMR1_START = 0x01
};


#ifdef ENABLE_OPL_LOG
int opl_do_log = ENABLE_OPL_LOG;


static void
opl_log(const char *fmt, ...)
{
    va_list ap;

    if (opl_do_log) {
	va_start(ap, fmt);
	pclog_ex(fmt, ap);
	va_end(ap);
    }
}
#else
#define opl_log(fmt, ...)
#endif


static void
timer_tick(opl_t *dev, int tmr)
{
    dev->timer_cur_count[tmr] = (dev->timer_cur_count[tmr] + 1) & 0xff;

    opl_log("Ticking timer %i, count now %02X...\n", tmr, dev->timer_cur_count[tmr]);

    if (dev->timer_cur_count[tmr] == 0x00) {
	dev->status |= ((STAT_TMR1_OVER >> tmr) & ~dev->timer_ctrl);
	dev->timer_cur_count[tmr] = dev->timer_count[tmr];

	opl_log("Count wrapped around to zero, reloading timer %i (%02X), status = %02X...\n", tmr, (STAT_TMR1_OVER >> tmr), dev->status);
    }

    timer_on_auto(&dev->timers[tmr], (tmr == 1) ? 320.0 : 80.0);
}


static void
timer_control(opl_t *dev, int tmr, int start)
{
    timer_on_auto(&dev->timers[tmr], 0.0);

    if (start) {
	opl_log("Loading timer %i count: %02X = %02X\n", tmr, dev->timer_cur_count[tmr], dev->timer_count[tmr]);
	dev->timer_cur_count[tmr] = dev->timer_count[tmr];
	if (dev->flags & FLAG_OPL3)
		timer_tick(dev, tmr);	/* Per the YMF 262 datasheet, OPL3 starts counting immediately, unlike OPL2. */
	else
		timer_on_auto(&dev->timers[tmr], (tmr == 1) ? 320.0 : 80.0);
    } else {
		opl_log("Timer %i stopped\n", tmr);
		if (tmr == 1) {
			dev->status &= ~STAT_TMR2_OVER;
		} else
			dev->status &= ~STAT_TMR1_OVER;
	}
}


static void
timer_1(void *priv)
{
    opl_t *dev = (opl_t *)priv;

    timer_tick(dev, 0);
}


static void
timer_2(void *priv)
{
    opl_t *dev = (opl_t *)priv;

    timer_tick(dev, 1);
}


static uint8_t
opl_read(opl_t *dev, uint16_t port)
{
    uint8_t ret = 0xff;

    if ((port & 0x0003) == 0x0000) {
	ret = dev->status;
	if (dev->status & STAT_TMR_OVER)
		ret |= STAT_TMR_ANY;
    }

	opl_log("OPL statret = %02x, status = %02x\n", ret, dev->status);

    return ret;
}


static void
opl_write(opl_t *dev, uint16_t port, uint8_t val)
{
    if ((port & 0x0001) == 0x0001) {
	nuked_write_reg_buffered(dev->opl, dev->port, val);

	switch (dev->port) {
		case 0x02:	/* Timer 1 */
			dev->timer_count[0] = val;
			opl_log("Timer 0 count now: %i\n", dev->timer_count[0]);
			break;

		case 0x03:	/* Timer 2 */
			dev->timer_count[1] = val;
			opl_log("Timer 1 count now: %i\n", dev->timer_count[1]);
			break;

		case 0x04:	/* Timer control */
			if (val & CTRL_RESET) {
				opl_log("Resetting timer status...\n");
				dev->status &= ~STAT_TMR_OVER;
			} else {
				dev->timer_ctrl = val;
				timer_control(dev, 0, val & CTRL_TMR1_START);
				timer_control(dev, 1, val & CTRL_TMR2_START);
				opl_log("Status mask now %02X (val = %02X)\n", (val & ~CTRL_TMR_MASK) & CTRL_TMR_MASK, val);
			}
			break;
	}
    } else {
	dev->port = nuked_write_addr(dev->opl, port, val) & 0x01ff;

	if (!(dev->flags & FLAG_OPL3))
		dev->port &= 0x00ff;
    }
}


void
opl_set_do_cycles(opl_t *dev, int8_t do_cycles)
{
    if (do_cycles)
	dev->flags |= FLAG_CYCLES;
    else
	dev->flags &= ~FLAG_CYCLES;
}


static void
opl_init(opl_t *dev, int is_opl3)
{
    memset(dev, 0x00, sizeof(opl_t));

    dev->flags = FLAG_CYCLES;
    if (is_opl3)
	dev->flags |= FLAG_OPL3;
    else
	dev->status = 0x06;

    /* Create a NukedOPL object. */
    dev->opl = nuked_init(48000);

    timer_add(&dev->timers[0], timer_1, dev, 0);
    timer_add(&dev->timers[1], timer_2, dev, 0);
}


void
opl_close(opl_t *dev)
{
    /* Release the NukedOPL object. */
    if (dev->opl) {
	nuked_close(dev->opl);
	dev->opl = NULL;
    }
}


uint8_t
opl2_read(uint16_t port, void *priv)
{
    opl_t *dev = (opl_t *)priv;

    if (dev->flags & FLAG_CYCLES)
	cycles -= ((int) (isa_timing * 8));

    opl2_update(dev);
	opl_log("OPL2 port read = %04x\n", port);
	
    return(opl_read(dev, port));
}


void
opl2_write(uint16_t port, uint8_t val, void *priv)
{
    opl_t *dev = (opl_t *)priv;

    opl2_update(dev);

	opl_log("OPL2 port write = %04x\n", port);
    opl_write(dev, port, val);
}


void
opl2_init(opl_t *dev)
{
    opl_init(dev, 0);
}


void
opl2_update(opl_t *dev)
{
    if (dev->pos >= sound_pos_global) {
		return;
	}

    nuked_generate_stream(dev->opl,
			  &dev->buffer[dev->pos * 2],
			  sound_pos_global - dev->pos);

    for (; dev->pos < sound_pos_global; dev->pos++) {
	dev->buffer[dev->pos * 2] /= 2;
	dev->buffer[(dev->pos * 2) + 1] = dev->buffer[dev->pos * 2];
    }
}


uint8_t
opl3_read(uint16_t port, void *priv)
{
    opl_t *dev = (opl_t *)priv;

    if (dev->flags & FLAG_CYCLES)
	cycles -= ((int)(isa_timing * 8));

    opl3_update(dev);

    return(opl_read(dev, port));
}


void
opl3_write(uint16_t port, uint8_t val, void *priv)
{
    opl_t *dev = (opl_t *)priv;
	
    opl3_update(dev);

    opl_write(dev, port, val);
}


void
opl3_init(opl_t *dev)
{
    opl_init(dev, 1);
}


/* API to sound interface. */
void
opl3_update(opl_t *dev)
{
    if (dev->pos >= sound_pos_global)
	return;

    nuked_generate_stream(dev->opl,
			  &dev->buffer[dev->pos * 2],
			  sound_pos_global - dev->pos);

    for (; dev->pos < sound_pos_global; dev->pos++) {
	dev->buffer[dev->pos * 2] /= 2;
	dev->buffer[(dev->pos * 2) + 1] /= 2;
    }
}