/*
 * VARCem	Virtual ARchaeological Computer EMulator.
 *		An emulator of (mostly) x86-based PC systems and devices,
 *		using the ISA,EISA,VLB,MCA  and PCI system buses, roughly
 *		spanning the era between 1981 and 1995.
 *
 *		This file is part of the VARCem Project.
 *
 *		Implement the PIT (Programmable Interval Timer.)
 *
 * Version:	@(#)pit.c	1.0.4	2018/03/27
 *
 * Authors:	Fred N. van Kempen, <decwiz@yahoo.com>
 *		Miran Grca, <mgrca8@gmail.com>
 *		Sarah Walker, <tommowalker@tommowalker.co.uk>
 *
 *		Copyright 2017,2018 Fred N. van Kempen.
 *		Copyright 2016-2018 Miran Grca.
 *		Copyright 2008-2018 Sarah Walker.
 *
 * 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 <stdio.h>
#include <stdint.h>
#include <string.h>
#include <wchar.h>
#include "emu.h"
#include "cpu/cpu.h"
#include "dma.h"
#include "io.h"
#include "nmi.h"
#include "pic.h"
#include "pit.h"
#include "ppi.h"
#include "device.h"
#include "timer.h"
#include "machine/machine.h"
#include "sound/sound.h"
#include "sound/snd_speaker.h"
#include "video/video.h"


/*B0 to 40, two writes to 43, then two reads - value does not change!*/
/*B4 to 40, two writes to 43, then two reads - value _does_ change!*/
int	displine;
int	firsttime = 1;
PIT	pit,
	pit2;
float	cpuclock;
float	isa_timing, bus_timing;
double	PITCONST;
float	CGACONST;
float	MDACONST;
float	VGACONST1,
	VGACONST2;
float	RTCCONST;


static void
pit_set_out(PIT *pit, int t, int out)
{
    pit->set_out_funcs[t](out, pit->out[t]);
    pit->out[t] = out;
}


static void
pit_load(PIT *pit, int t)
{
    int l = pit->l[t] ? pit->l[t] : 0x10000;

    timer_clock();

    pit->newcount[t] = 0;
    pit->disabled[t] = 0;

    switch (pit->m[t]) {
	case 0: /*Interrupt on terminal count*/
                pit->count[t] = l;
                pit->c[t] = (int64_t)((((int64_t) l) << TIMER_SHIFT) * PITCONST);
		pit_set_out(pit, t, 0);
		pit->thit[t] = 0;
		pit->enabled[t] = pit->gate[t];
		break;

	case 1: /*Hardware retriggerable one-shot*/
		pit->enabled[t] = 1;
		break;

	case 2: /*Rate generator*/
		if (pit->initial[t]) {
                        pit->count[t] = l - 1;
                        pit->c[t] = (int64_t)(((((int64_t) l) - 1LL) << TIMER_SHIFT) * PITCONST);
			pit_set_out(pit, t, 1);
			pit->thit[t] = 0;
		}
		pit->enabled[t] = pit->gate[t];
		break;

	case 3: /*Square wave mode*/
		if (pit->initial[t]) {
                        pit->count[t] = l;
                        pit->c[t] = (int64_t)((((((int64_t) l) + 1LL) >> 1) << TIMER_SHIFT) * PITCONST);
			pit_set_out(pit, t, 1);
			pit->thit[t] = 0;
		}
		pit->enabled[t] = pit->gate[t];
		break;

	case 4: /*Software triggered stobe*/
		if (!pit->thit[t] && !pit->initial[t]) {
			pit->newcount[t] = 1;
		} else {
                        pit->count[t] = l;
                        pit->c[t] = (int64_t)((l << TIMER_SHIFT) * PITCONST);
			pit_set_out(pit, t, 0);
			pit->thit[t] = 0;
		}
		pit->enabled[t] = pit->gate[t];
		break;

	case 5: /*Hardware triggered stobe*/
		pit->enabled[t] = 1;
		break;
    }

    pit->initial[t] = 0;
    pit->running[t] = pit->enabled[t] &&
		      pit->using_timer[t] && !pit->disabled[t];

    timer_update_outstanding();
}


static void
pit_over(PIT *pit, int t)
{
    int64_t l = pit->l[t] ? pit->l[t] : 0x10000LL;

    if (pit->disabled[t]) {
	pit->count[t] += 0xffff;
	pit->c[t] += (int64_t)(((int64_t)0xffff << TIMER_SHIFT) * PITCONST);
	return;
    }

    switch (pit->m[t]) {
	case 0: /*Interrupt on terminal count*/
	case 1: /*Hardware retriggerable one-shot*/
		if (! pit->thit[t])
			pit_set_out(pit, t, 1);
		pit->thit[t] = 1;
		pit->count[t] += 0xffff;
		pit->c[t] += (int64_t)(((int64_t)0xffff << TIMER_SHIFT) * PITCONST);
		break;

	case 2: /*Rate generator*/
		pit->count[t] += (int)l;
		pit->c[t] += (int64_t)((l << TIMER_SHIFT) * PITCONST);
		pit_set_out(pit, t, 0);
		pit_set_out(pit, t, 1);
		break;

	case 3: /*Square wave mode*/
		if (pit->out[t]) {
			pit_set_out(pit, t, 0);
			pit->count[t] += (int)(l >> 1);
			pit->c[t] += (int64_t)(((l >> 1) << TIMER_SHIFT) * PITCONST);
		} else {
			pit_set_out(pit, t, 1);
			pit->count[t] += (int)((l + 1) >> 1);
			pit->c[t] = (int64_t)((((l + 1) >> 1) << TIMER_SHIFT) * PITCONST);
		}
		break;

	case 4: /*Software triggered strove*/
		if (! pit->thit[t]) {
			pit_set_out(pit, t, 0);
			pit_set_out(pit, t, 1);
		}
		if (pit->newcount[t]) {
			pit->newcount[t] = 0;
			pit->count[t] += (int)l;
			pit->c[t] += (int64_t)((l << TIMER_SHIFT) * PITCONST);
		} else {
			pit->thit[t] = 1;
			pit->count[t] += 0xffff;
			pit->c[t] += (int64_t)(((int64_t)0xffff << TIMER_SHIFT) * PITCONST);
		}
		break;

	case 5: /*Hardware triggered strove*/
		if (! pit->thit[t]) {
			pit_set_out(pit, t, 0);
			pit_set_out(pit, t, 1);
		}
		pit->thit[t] = 1;
		pit->count[t] += 0xffff;
		pit->c[t] += (int64_t)(((int64_t)0xffff << TIMER_SHIFT) * PITCONST);
		break;
    }

    pit->running[t] = pit->enabled[t] &&
		      pit->using_timer[t] && !pit->disabled[t];
}


static void
pit_set_gate_no_timer(PIT *pit, int t, int gate)
{
    int64_t l = pit->l[t] ? pit->l[t] : 0x10000LL;

    if (pit->disabled[t]) {
	pit->gate[t] = gate;
	return;
    }

    switch (pit->m[t]) {
	case 0: /*Interrupt on terminal count*/
	case 4: /*Software triggered stobe*/
		pit->enabled[t] = gate;
		break;

	case 1: /*Hardware retriggerable one-shot*/
	case 5: /*Hardware triggered stobe*/
		if (gate && !pit->gate[t]) {
			pit->count[t] = (int)l;
                        pit->c[t] = (int64_t)((l << TIMER_SHIFT) * PITCONST);
			pit_set_out(pit, t, 0);
			pit->thit[t] = 0;
			pit->enabled[t] = 1;
		}
		break;

	case 2: /*Rate generator*/
		if (gate && !pit->gate[t]) {
			pit->count[t] = (int)(l - 1);
                        pit->c[t] = (int64_t)((l << TIMER_SHIFT) * PITCONST);
			pit_set_out(pit, t, 1);
			pit->thit[t] = 0;
		}		
		pit->enabled[t] = gate;
		break;

	case 3: /*Square wave mode*/
		if (gate && !pit->gate[t]) {
			pit->count[t] = (int)l;
			pit->c[t] = (int64_t)((((l+1)>>1)<<TIMER_SHIFT)*PITCONST);
			pit_set_out(pit, t, 1);
			pit->thit[t] = 0;
		}
		pit->enabled[t] = gate;
		break;
    }

    pit->gate[t] = gate;
    pit->running[t] = pit->enabled[t] &&
		      pit->using_timer[t] && !pit->disabled[t];
}


static void
pit_clock(PIT *pit, int t)
{
    if (pit->thit[t] || !pit->enabled[t]) return;

    if (pit->using_timer[t]) return;

    pit->count[t] -= (pit->m[t] == 3) ? 2 : 1;
    if (! pit->count[t])
	pit_over(pit, t);
}


static void
pit_timer_over(void *priv)
{
    PIT_nr *pit_nr = (PIT_nr *)priv;
    PIT *pit = pit_nr->pit;
    int timer = pit_nr->nr;

    pit_over(pit, timer);
}


static int
pit_read_timer(PIT *pit, int t)
{
    int r;

    timer_clock();

    if (pit->using_timer[t] && !(pit->m[t] == 3 && !pit->gate[t])) {
	r = (int)((int64_t)((pit->c[t] + ((1LL << TIMER_SHIFT) - 1)) / PITCONST) >> TIMER_SHIFT);

	if (pit->m[t] == 2)
		r++;
	if (r < 0)
		r = 0;
	if (r > 0x10000)
		r = 0x10000;
	if (pit->m[t] == 3)
		r <<= 1;

	return r;
    }

    if (pit->m[t] == 2)
	return (pit->count[t] + 1);

    return pit->count[t];
}


static void
pit_write(uint16_t addr, uint8_t val, void *priv)
{
    PIT *pit = (PIT *)priv;
    int t;

    cycles -= (int)PITCONST;

    switch (addr & 3) {
	case 3: /*CTRL*/
		if ((val & 0xc0) == 0xc0) {
			 if (! (val & 0x20)) {
				if (val & 2)
					pit->rl[0] = (uint32_t)pit_read_timer(pit, 0);
				if (val & 4)
					pit->rl[1] = (uint32_t)pit_read_timer(pit, 1);
				if (val & 8)
					pit->rl[2] = (uint32_t)pit_read_timer(pit, 2);
			}
			if (! (val & 0x10)) {
				if (val & 2) {
					pit->read_status[0] = (pit->ctrls[0] & 0x3f) | (pit->out[0] ? 0x80 : 0);
					pit->do_read_status[0] = 1;
				}
				if (val & 4) {
					pit->read_status[1] = (pit->ctrls[1] & 0x3f) | (pit->out[1] ? 0x80 : 0);
					pit->do_read_status[1] = 1;
				}
				if (val & 8) {
					pit->read_status[2] = (pit->ctrls[2] & 0x3f) | (pit->out[2] ? 0x80 : 0);
					pit->do_read_status[2] = 1;
				}
			}
			return;
		}
		t = val >> 6;
		pit->ctrl = val;
		if ((val >> 7) == 3)
			return;

		if (! (pit->ctrl & 0x30)) {
			pit->rl[t] = (uint32_t)pit_read_timer(pit, t);
			pit->ctrl |= 0x30;
			pit->rereadlatch[t] = 0;
			pit->rm[t] = 3;
			pit->latched[t] = 1;
		} else {
			pit->ctrls[t] = val;
			pit->rm[t] = pit->wm[t] = (pit->ctrl >> 4) & 3;
			pit->m[t] = (val >> 1) & 7;
			if (pit->m[t]>5)
				pit->m[t] &= 3;
			if (! (pit->rm[t])) {
				pit->rm[t] = 3;
				pit->rl[t] = (uint32_t)pit_read_timer(pit, t);
			}
			pit->rereadlatch[t] = 1;
			pit->initial[t] = 1;
			if (! pit->m[t])
				pit_set_out(pit, t, 0);
			  else
				pit_set_out(pit, t, 1);
			pit->disabled[t] = 1;
		}
		pit->wp = 0;
		pit->thit[t] = 0;
		break;

	case 0: /*Timers*/
	case 1:
	case 2:
		t = addr & 3;
		switch (pit->wm[t]) {
			case 1:
				pit->l[t] = val;
				pit_load(pit, t);
				break;

			case 2:
				pit->l[t] = (val << 8);
				pit_load(pit, t);
				break;

			case 0:
				pit->l[t] &= 0xff;
				pit->l[t] |= (val << 8);
				pit_load(pit, t);
				pit->wm[t] = 3;
				break;

			case 3:
				pit->l[t] &= 0xff00;
				pit->l[t] |= val;
				pit->wm[t] = 0;
				break;
		}

		speakval = (int)(((float)pit->l[2]/(float)pit->l[0])*0x4000)-0x2000;
		if (speakval > 0x2000)
			speakval = 0x2000;
		break;
    }
}


static uint8_t
pit_read(uint16_t addr, void *priv)
{
    PIT *pit = (PIT *)priv;
    uint8_t temp = 0xff;
    int t;

    cycles -= (int)PITCONST;

    switch (addr&3) {
	case 0: /*Timers*/
	case 1:
	case 2:
		t = addr & 3;
		if (pit->do_read_status[t]) {
			pit->do_read_status[t] = 0;
			temp = pit->read_status[t];
			break;
		}
		if (pit->rereadlatch[addr & 3] && !pit->latched[addr & 3]) {
			pit->rereadlatch[addr & 3] = 0;
			pit->rl[t] = pit_read_timer(pit, t);
		}
		switch (pit->rm[addr & 3]) {
			case 0:
				temp = pit->rl[addr & 3] >> 8;
				pit->rm[addr & 3] = 3;
				pit->latched[addr & 3] = 0;
				pit->rereadlatch[addr & 3] = 1;
				break;

			case 1:
				temp = (pit->rl[addr & 3]) & 0xff;
				pit->latched[addr & 3] = 0;
				pit->rereadlatch[addr & 3] = 1;
				break;

			case 2:
				temp = (pit->rl[addr & 3]) >> 8;
				pit->latched[addr & 3] = 0;
				pit->rereadlatch[addr & 3] = 1;
				break;

			case 3:
				temp = (pit->rl[addr & 3]) & 0xFF;
				if (pit->m[addr & 3] & 0x80)
					pit->m[addr & 3] &= 7;
				  else
					pit->rm[addr & 3] = 0;
				break;
		}
		break;

	case 3: /*Control*/
		temp = pit->ctrl;
		break;
    }

    return temp;
}


static void
pit_null_timer(int new_out, int old_out)
{
}


static void
pit_irq0_timer(int new_out, int old_out)
{
    if (new_out && !old_out)
	picint(1);

    if (! new_out)
	picintc(1);
}


static void
pit_speaker_timer(int new_out, int old_out)
{
    int64_t l;

    speaker_update();

    l = pit.l[2] ? pit.l[2] : 0x10000LL;
    if (l < 25LL)
	speakon = 0;
      else
	speakon = new_out;

    ppispeakon = new_out;
}


void
pit_init(void)
{
    pit_reset(&pit);

    io_sethandler(0x0040, 4,
		  pit_read,NULL,NULL, pit_write,NULL,NULL, &pit);

    pit.gate[0] = pit.gate[1] = 1;
    pit.gate[2] = 0;
    pit.using_timer[0] = pit.using_timer[1] = pit.using_timer[2] = 1;

    pit.pit_nr[0].nr = 0;
    pit.pit_nr[1].nr = 1;
    pit.pit_nr[2].nr = 2;
    pit.pit_nr[0].pit = pit.pit_nr[1].pit = pit.pit_nr[2].pit = &pit;

    timer_add(pit_timer_over,
	      &pit.c[0], &pit.running[0], (void *)&pit.pit_nr[0]);
    timer_add(pit_timer_over,
	      &pit.c[1], &pit.running[1], (void *)&pit.pit_nr[1]);
    timer_add(pit_timer_over,
	      &pit.c[2], &pit.running[2], (void *)&pit.pit_nr[2]);

    pit_set_out_func(&pit, 0, pit_irq0_timer);
    pit_set_out_func(&pit, 1, pit_null_timer);
    pit_set_out_func(&pit, 2, pit_speaker_timer);
}


static void
pit_ps2_irq0(int new_out, int old_out)
{
    if (new_out && !old_out) {
	picint(1);
	pit_set_gate_no_timer(&pit2, 0, 1);
    }

    if (! new_out)
	picintc(1);

    if (!new_out && old_out)
	pit_clock(&pit2, 0);
}


static void
pit_ps2_nmi(int new_out, int old_out)
{
    nmi = new_out;

    if (nmi)
	nmi_auto_clear = 1;
}


void
pit_ps2_init(void)
{
    pit_reset(&pit2);

    io_sethandler(0x0044, 1,
		  pit_read,NULL,NULL, pit_write,NULL,NULL, &pit2);
    io_sethandler(0x0047, 1,
		  pit_read,NULL,NULL, pit_write,NULL,NULL, &pit2);

    pit2.gate[0] = 0;
    pit2.using_timer[0] = 0;
    pit2.disabled[0] = 1;

    pit2.pit_nr[0].nr = 0;
    pit2.pit_nr[0].pit = &pit2;

    timer_add(pit_timer_over,
	      &pit2.c[0], &pit2.running[0], (void *)&pit2.pit_nr[0]);

    pit_set_out_func(&pit, 0, pit_ps2_irq0);
    pit_set_out_func(&pit2, 0, pit_ps2_nmi);
}


void
pit_reset(PIT *pit)
{
    void (*old_set_out_funcs[3])(int new_out, int old_out);
    PIT_nr old_pit_nr[3];

    memcpy(old_set_out_funcs, pit->set_out_funcs, 3 * sizeof(void *));
    memcpy(old_pit_nr, pit->pit_nr, 3 * sizeof(PIT_nr));
    memset(pit, 0, sizeof(PIT));
    memcpy(pit->set_out_funcs, old_set_out_funcs, 3 * sizeof(void *));
    memcpy(pit->pit_nr, old_pit_nr, 3 * sizeof(PIT_nr));

    pit->l[0] = 0xffff; pit->c[0] = (int64_t)(0xffffLL*PITCONST);
    pit->l[1] = 0xffff; pit->c[1] = (int64_t)(0xffffLL*PITCONST);
    pit->l[2] = 0xffff; pit->c[2] = (int64_t)(0xffffLL*PITCONST);
    pit->m[0] = pit->m[1] = pit->m[2] = 0;
    pit->ctrls[0] = pit->ctrls[1] = pit->ctrls[2] = 0;
    pit->thit[0] = 1;
    pit->gate[0] = pit->gate[1] = 1;
    pit->gate[2] = 0;
    pit->using_timer[0] = pit->using_timer[1] = pit->using_timer[2] = 1;
}


void
setpitclock(float clock)
{
    cpuclock = clock;

    TIMER_USEC = (int64_t)((clock / 1000000.0f) * (float)(1 << TIMER_SHIFT));

    PITCONST = clock/(1193181.0f + (2.0f / 3.0f));
    RTCCONST = clock/32768.0f;
    CGACONST = (clock/(19687503.0f/11.0f));
    MDACONST = (clock/2032125.0f);
    VGACONST1 = (clock/25175000.0f);
    VGACONST2 = (clock/28322000.0f);

    isa_timing = clock/8000000.0f;
    bus_timing = clock/(float)cpu_busspeed;

    video_update_timing();

    xt_cpu_multi = (int)((14318184.0*(double)(1 << TIMER_SHIFT)) / (double)machines[machine].cpu[cpu_manufacturer].cpus[cpu_effective].rspeed);

    device_speed_changed();
}


void
clearpit(void)
{
    pit.c[0] = (pit.l[0]<<2);
}


int
pit_get_timer_0(void)
{
    int r = (int)((int64_t)((pit.c[0] + ((1LL << TIMER_SHIFT) - 1)) / PITCONST) >> TIMER_SHIFT);

    if (pit.m[0] == 2)
	r++;
    if (r < 0)
	r = 0;
    if (r > 0x10000)
	r = 0x10000;
    if (pit.m[0] == 3)
	r <<= 1;

    return r;
}


float
pit_timer0_freq(void)
{
    if (pit.l[0])
	return (1193181.0f + (2.0f / 3.0f))/(float)pit.l[0];
      else
	return (1193181.0f + (2.0f / 3.0f))/(float)0x10000;
}


void
pit_set_gate(PIT *pit, int t, int gate)
{
    if (pit->disabled[t]) {
	pit->gate[t] = gate;
	return;
    }

    timer_process();

    pit_set_gate_no_timer(pit, t, gate);

    timer_update_outstanding();
}


void
pit_set_using_timer(PIT *pit, int t, int using_timer)
{
    timer_process();

    if (pit->using_timer[t] && !using_timer)
	pit->count[t] = pit_read_timer(pit, t);
    if (!pit->using_timer[t] && using_timer)
	pit->c[t] = (int64_t)((((int64_t) pit->count[t]) << TIMER_SHIFT) * PITCONST);

    pit->using_timer[t] = using_timer;
    pit->running[t] = pit->enabled[t] &&
		      pit->using_timer[t] && !pit->disabled[t];

    timer_update_outstanding();
}


void
pit_set_out_func(PIT *pit, int t, void (*func)(int new_out, int old_out))
{
    pit->set_out_funcs[t] = func;
}


void
pit_irq0_timer_pcjr(int new_out, int old_out)
{
    if (new_out && !old_out) {
	picint(1);
	pit_clock(&pit, 1);
    }

    if (! new_out)
	picintc(1);
}


void
pit_refresh_timer_xt(int new_out, int old_out)
{
    if (new_out && !old_out)
	dma_channel_read(0);
}


void
pit_refresh_timer_at(int new_out, int old_out)
{
    if (new_out && !old_out)
	ppi.pb ^= 0x10;
}