/* DL11W.cpp: sample UNIBUS controller with SLU & LTC logic

 Copyright (c) 2018, Joerg Hoppe
 j_hoppe@t-online.de, www.retrocmp.com

 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),
 to deal in the Software without restriction, including without limitation
 the rights to use, copy, modify, merge, publish, distribute, sublicense,
 and/or sell copies of the Software, and to permit persons to whom the
 Software is furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 JOERG HOPPE BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 12-nov-2018  JH      entered beta phase
 20/12/2018 djrm copied to make slu device
 14/01/2019 djrm adapted to use UART2 serial port

 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <assert.h>
#include <errno.h>
#include <iostream>
#include <netdb.h>
#include <netinet/in.h>

#include "utils.hpp"
#include "gpios.hpp"
#include "logsource.hpp"
#include "unibusadapter.hpp"
#include "unibusdevice.hpp"	// definition of class device_c
#include "unibus.h"
#include "dl11w.hpp"

#include "rs232.hpp"
#include "rs232adapter.hpp"

//-------------------------------------------------

slu_c::slu_c() :
		unibusdevice_c() {
	set_workers_count(2); // receiver and transmitte have own threads

	//ip_host.value = IP_HOST; // not used
	//ip_port.value = IP_PORT; // not used

	// static config
	name.value = "DL11";
	type_name.value = "slu_c";
	log_label = "slu";

	break_enable.value = 1; // SW4-1 default ON
	error_bits_enable.value = 1; // SE4-7 default ON

	// SLU has 2 Interrupt vectors: base = RCV, base+= XMT
	// put in slot 1, closest to CPU
	set_default_bus_params(SLU_ADDR, SLU_SLOT, SLU_VECTOR, SLU_LEVEL); // base addr, intr-vector, intr level

	// controller has some register
	register_count = slu_idx_count;

	reg_rcsr = &(this->registers[slu_idx_rcsr]); // @  base addr
	strcpy(reg_rcsr->name, "RCSR"); // Receiver Status Register
	reg_rcsr->active_on_dati = false;
	reg_rcsr->active_on_dato = true;
	reg_rcsr->reset_value = 0;
	reg_rcsr->writable_bits = 0xff;

	reg_rbuf = &(this->registers[slu_idx_rbuf]); // @  base addr
	strcpy(reg_rbuf->name, "RBUF"); // Receiver Buffer Register
	reg_rbuf->active_on_dati = true;
	reg_rbuf->active_on_dato = true; // required for "active on dati""
	reg_rbuf->reset_value = 0;
	reg_rbuf->writable_bits = 0x00;

	reg_xcsr = &(this->registers[slu_idx_xcsr]); // @  base addr
	strcpy(reg_xcsr->name, "XCSR"); // Transmitter Status Register
	reg_xcsr->active_on_dati = false;
	reg_xcsr->active_on_dato = true;
	reg_xcsr->reset_value = XCSR_XMIT_RDY; // set
	reg_xcsr->writable_bits = 0xff;

	reg_xbuf = &(this->registers[slu_idx_xbuf]); // @  base addr
	strcpy(reg_xbuf->name, "XBUF"); //Transmitter Buffer Register
	reg_xbuf->active_on_dati = false; // no controller state change
	reg_xbuf->active_on_dato = true;
	reg_xbuf->reset_value = 0;
	reg_xbuf->writable_bits = 0xff;

	// initialize serial format
	serialport.value = "ttyS2"; // labeled "UART2" on PCB
	baudrate.value = 9600;
	mode.value = "8N1";

	rs232adapter.rs232 = &rs232;
}

slu_c::~slu_c() {
}

bool slu_c::on_param_changed(parameter_c *param) {
	if (param == &enabled) {
		if (enabled.new_value) {
			// enable SLU: setup COM serial port
			// setup for BREAK and parity evaluation
			rs232adapter.rcv_termios_error_encoding = true;
			if (rs232.OpenComport(serialport.value.c_str(), baudrate.value, mode.value.c_str(),
			true)) {
				ERROR("Can not open serial port %s", serialport.value.c_str());
				return false; // reject "enable"
			}

			// lock serial port and settings
			serialport.readonly = true;
			baudrate.readonly = true;
			mode.readonly = true;

			INFO("Serial port %s opened", serialport.value.c_str());
			char buff[256];
			sprintf(buff, "Serial port %s opened\n\r", serialport.value.c_str());
			rs232.cputs(buff);
		} else {
			// disable SLU
			rs232.CloseComport();
			// unlock serial port and settings
			serialport.readonly = false;
			baudrate.readonly = false;
			mode.readonly = false;
			INFO("Serial port %s closed", serialport.value.c_str());
		}
	} else if (param == &priority_slot) {
		rcvintr_request.set_priority_slot(priority_slot.new_value);
		// XMT INTR: lower priority => nxt slot, and next vector
		xmtintr_request.set_priority_slot(priority_slot.new_value + 1);
	} else if (param == &intr_vector) {
		rcvintr_request.set_vector(intr_vector.new_value);
		xmtintr_request.set_vector(intr_vector.new_value + 4);
	} else if (param == &intr_level) {
		rcvintr_request.set_level(intr_level.new_value);
		xmtintr_request.set_level(intr_level.new_value);
	}
	return unibusdevice_c::on_param_changed(param); // more actions (for enable)
}

//--------------------------------------------

// calc static INTR condition level. 
// Change of that condition calculated by intr_request_c.is_condition_raised()
bool slu_c::get_rcv_intr_level(void) {
	return rcv_done && rcv_intr_enable;
}

// Update RCSR and optionally generate INTR
void slu_c::set_rcsr_dati_value_and_INTR(void) {
	uint16_t val = (rcv_active ? RCSR_RCVR_ACT : 0) | (rcv_done ? RCSR_RCVR_DONE : 0)
			| (rcv_intr_enable ? RCSR_RCVR_INT_ENB : 0);
	switch (rcvintr_request.edge_detect(get_rcv_intr_level())) {
	case intr_request_c::INTERRUPT_EDGE_RAISING:
		// set register atomically with INTR, if INTR not blocked
		unibusadapter->INTR(rcvintr_request, reg_rcsr, val);
		break;
	case intr_request_c::INTERRUPT_EDGE_FALLING:
		// BR4 is tied to monitor and enable, so raised INTRs may get canceled
		unibusadapter->cancel_INTR(rcvintr_request);
		set_register_dati_value(reg_rcsr, val, __func__);
		break;
	default:
		set_register_dati_value(reg_rcsr, val, __func__);
	}
}

// PDP-11 writes into RCSR
void slu_c::eval_rcsr_dato_value(void) {
	uint16_t val = get_register_dato_value(reg_rcsr);

	rcv_intr_enable = val & RCSR_RCVR_INT_ENB ? 1 : 0;
	rcv_rdr_enb = val & RCSR_RDR_ENB ? 1 : 0;
	if (rcv_rdr_enb)
		rcv_done = 0; // raising edge clears rcv_done
	// if rcvr_done and int enable goes high: INTR
	set_rcsr_dati_value_and_INTR();
}

// Update RBUF, readonly
void slu_c::set_rbuf_dati_value(void) {
	uint16_t val = 0;
	if (error_bits_enable.value) {
		val = (rcv_or_err ? RBUF_OR_ERR : 0) | (rcv_fr_err ? RBUF_FR_ERR : 0)
				| (rcv_p_err ? RBUF_P_ERR : 0);
		if (val) // set general error flag
			val |= RBUF_ERROR;
	}
	val |= rcv_buffer; // received char in bits 7..0
	set_register_dati_value(reg_rbuf, val, __func__);
}

bool slu_c::get_xmt_intr_level() {
	return xmt_ready && xmt_intr_enable;
}

// Update Transmit Status Register XCSR and optionally generate INTR
void slu_c::set_xcsr_dati_value_and_INTR(void) {
	uint16_t val = (xmt_ready ? XCSR_XMIT_RDY : 0) | (xmt_intr_enable ? XCSR_XMIT_INT_ENB : 0)
			| (xmt_maint ? XCSR_MAINT : 0) | (xmt_break ? XCSR_BREAK : 0);
	switch (xmtintr_request.edge_detect(get_xmt_intr_level())) {
	case intr_request_c::INTERRUPT_EDGE_RAISING:
		// set register atomically with INTR, if INTR not blocked
		unibusadapter->INTR(xmtintr_request, reg_xcsr, val);
		break;
	case intr_request_c::INTERRUPT_EDGE_FALLING:
		// BR4 is tied to monitor and enable, so raised INTRs may get canceled
		unibusadapter->cancel_INTR(xmtintr_request);
		set_register_dati_value(reg_xcsr, val, __func__);
		break;
	default:
		set_register_dati_value(reg_xcsr, val, __func__);
	}

}

void slu_c::eval_xcsr_dato_value(void) {
	uint16_t val = get_register_dato_value(reg_xcsr);
	bool old_break = xmt_break;
	xmt_intr_enable = val & XCSR_XMIT_INT_ENB ? 1 : 0;
	xmt_maint = val & XCSR_MAINT ? 1 : 0;
	xmt_break = val & XCSR_BREAK ? 1 : 0;
	// if xmt_ready and int enable goes high: INTR
	set_xcsr_dati_value_and_INTR();

	if (old_break != xmt_break) {
		// re-evaluate break state on bit change
		if (break_enable.value)
			rs232.SetBreak(xmt_break);
		else
			rs232.SetBreak(0);
	}
}

void slu_c::eval_xbuf_dato_value(void) {
	// transmit data buffer contains only the character in bits 7..0
	xmt_buffer = get_register_dato_value(reg_xbuf) & 0xff;
}

// process DATI/DATO access to one of my "active" registers
// !! called asynchronuously by PRU, with SSYN asserted and blocking UNIBUS.
// The time between PRU event and program flow into this callback
// is determined by ARM Linux context switch
//
// UNIBUS DATO cycles let dati_flipflops "flicker" outside of this proc:
//      do not read back dati_flipflops.
void slu_c::on_after_register_access(unibusdevice_register_t *device_reg,
		uint8_t unibus_control) {

//	if (unibus_control == UNIBUS_CONTROL_DATO) // bus write 
//		set_register_dati_value(device_reg, device_reg->active_dato_flipflops, __func__);

	if (unibusadapter->line_INIT)
		return; // do nothing wile reset

	switch (device_reg->index) {

	case slu_idx_rcsr:
		if (unibus_control == UNIBUS_CONTROL_DATO) { // bus write into RCSR
			pthread_mutex_lock(&on_after_rcv_register_access_mutex); // signal changes atomic against UNIBUS accesses
			eval_rcsr_dato_value(); // may generate INTR
			set_rcsr_dati_value_and_INTR();
			// ignore reader enable
			pthread_mutex_unlock(&on_after_rcv_register_access_mutex);
		}
		break;
	case slu_idx_rbuf: { // DATI/DATO: is read only, but write also clears "rcvr_done"
		// signal data has been read from bus
		pthread_mutex_lock(&on_after_rcv_register_access_mutex);
		rcv_done = 0;
		set_rcsr_dati_value_and_INTR();
		pthread_mutex_unlock(&on_after_rcv_register_access_mutex);
	}
		break;
	case slu_idx_xcsr:
		if (unibus_control == UNIBUS_CONTROL_DATO) { // bus write
			pthread_mutex_lock(&on_after_xmt_register_access_mutex);
			eval_xcsr_dato_value(); // may trigger INTR
			set_xcsr_dati_value_and_INTR();
			pthread_mutex_unlock(&on_after_xmt_register_access_mutex);
		}
		break;
	case slu_idx_xbuf:
		if (unibus_control == UNIBUS_CONTROL_DATO) { // bus write into XBUF
			pthread_mutex_lock(&on_after_xmt_register_access_mutex);
			eval_xbuf_dato_value();
			xmt_ready = 0; // signal worker: xmt_data pending
			set_xcsr_dati_value_and_INTR();
			// on_after_register_access_cond used for xmt worker
			pthread_cond_signal(&on_after_xmt_register_access_cond);
			pthread_mutex_unlock(&on_after_xmt_register_access_mutex);
		}
		break;
	default:
		break;
	}

}

void slu_c::on_power_changed(void) {
	if (power_down) { // power-on defaults
	}
}

// UNIBUS INIT: clear all registers
void slu_c::on_init_changed(void) {
	// write all registers to "reset-values"
	if (init_asserted) {
		reset_unibus_registers();
		rcv_active = 0;
		rcv_done = 0;
		rcv_intr_enable = 0;
		rcv_or_err = 0;
		rcv_fr_err = 0;
		rcv_p_err = 0;
		rcv_buffer = 0;
		xmt_ready = 1;
		xmt_intr_enable = 0;
		xmt_maint = 0;
		xmt_break = 0;
		rcvintr_request.edge_detect_reset();
		xmtintr_request.edge_detect_reset();
		// INFO("slu_c::on_init()");
	}
}

// background worker.
void slu_c::worker_rcv(void) {
	timeout_c timeout;
	int n;
	unsigned char buffer[BUFLEN + 1];

	// poll with frequency > baudrate, to see single bits
	//unsigned poll_periods_us = 1000000 / baudrate.value;

	/* Receiver not time critical? UARTS are buffering
	 So if thread is swapped out and back a burst of characters appear.
	 -> Wait after each character for transfer time before polling
	 RS232 again.
	 */
	unsigned poll_periods_us = (rs232.CharTransmissionTime_us * 9) / 10;
	// poll a bit faster to be ahead of char stream. 
	// don't oversample: PDP-11 must process char in that time

	// worker_init_realtime_priority(rt_device);

	while (!workers_terminate) {
		timeout.wait_us(poll_periods_us);
		if (unibusadapter->line_INIT)
			continue; // do nothing while reset
		// "query
		// rcv_active: can only be set by polling the UART input GPIO pin?
		// at the moments, it is only sent on maintenance loopback xmt
		/* read serial data, if any */
		if (rs232adapter.byte_rcv_poll(buffer)) {
			pthread_mutex_lock(&on_after_rcv_register_access_mutex); // signal changes atomic against UNIBUS accesses
			rcv_or_err = rcv_fr_err = rcv_p_err = 0;
			if (rcv_done) // not yet cleared? overrun!
				rcv_or_err = 1;
			if (buffer[0] == 0xff) {
				/* How to receive framing and parity errors:  see termios(3)
				 If IGNPAR=0, PARMRK=1: error on <char> received as \377 \0 <char> 
				 \377 received as \377 \377
				 */
				n = rs232adapter.byte_rcv_poll(buffer);
				assert(n);	// next char after 0xff escape immediately available

				if (buffer[0] == 0) { // error flags
					rcv_fr_err = rcv_p_err = 1;
					n = rs232adapter.byte_rcv_poll(buffer);
					assert(n); // next char after 0xff 0 seq is data"
					rcv_buffer = buffer[0];
				} else if (buffer[0] == 0xff) { // enocoded 0xff
					rcv_buffer = 0xff;
				} else {
					WARNING("Received 0xff <stray> seqeuence");
					rcv_buffer = buffer[0];
				}
			} else
				// received non escaped data byte
				rcv_buffer = buffer[0];
			rcv_done = 1;
			rcv_active = 0;
			set_rbuf_dati_value();
			set_rcsr_dati_value_and_INTR(); // INTR!
			pthread_mutex_unlock(&on_after_rcv_register_access_mutex); // signal changes atomic against UNIBUS accesses
		}
	}
}

void slu_c::worker_xmt(void) {
	timeout_c timeout;

	assert(!pthread_mutex_lock(&on_after_register_access_mutex));

	// Transmitter not time critical
	// worker_init_realtime_priority(rt_device);

	while (!workers_terminate) {
		// 1. wait for xmt signal
		int res = pthread_cond_wait(&on_after_xmt_register_access_cond,
				&on_after_xmt_register_access_mutex);
		// on_after_xmt_register_access_mutex remains locked all the time
		if (res != 0) {
			ERROR("SLU::worker_xmt() pthread_cond_wait = %d = %s>", res, strerror(res));
			continue;
		}

		// 2. transmit
		rs232adapter.byte_xmt_send(xmt_buffer);
		xmt_ready = 0;
		set_xcsr_dati_value_and_INTR();
		if (xmt_maint) { // loop back: simulate data byte coming in
			pthread_mutex_lock(&on_after_rcv_register_access_mutex);
			rcv_active = 1;
			set_rcsr_dati_value_and_INTR();
			pthread_mutex_unlock(&on_after_rcv_register_access_mutex);
		}

		// 3. wait for data byte being shifted out
		pthread_mutex_unlock(&on_after_xmt_register_access_mutex);
		timeout.wait_us(rs232.CharTransmissionTime_us);
		pthread_mutex_lock(&on_after_xmt_register_access_mutex);
		if (xmt_maint)
			// put sent byte into rcv buffer, receiver will poll it
			rs232adapter.byte_loopback(xmt_buffer);
		xmt_ready = 1;
		set_xcsr_dati_value_and_INTR();

		// has rcv or xmt interrupt priority on maintennace loop back
	}
	assert(!pthread_mutex_unlock(&on_after_xmt_register_access_mutex));
}

void slu_c::worker(unsigned instance) {
	// 2 parallel worker() instances: 0 and 1 
	if (instance == 0)
		worker_rcv();
	else
		worker_xmt();

}

//--------------------------------------------------------------------------------------------------

ltc_c::ltc_c() :
		unibusdevice_c()  // super class constructor
{

	// static config
	name.value = "KW11";
	type_name.value = "ltc_c";
	log_label = "ltc";
	// slot = 3:
	set_default_bus_params(LTC_ADDR, LTC_SLOT, LTC_VECTOR, LTC_LEVEL); // base addr, intr-vector, intr level

	// controller has only one register
	register_count = 1;
	reg_lks = &(this->registers[0]); // @  base addr
	strcpy(reg_lks->name, "LKS"); // Line Clock Status Register
	reg_lks->active_on_dati = false; // status polled by CPU, not active
	reg_lks->active_on_dato = true;
	reg_lks->reset_value = 0;
	reg_lks->writable_bits = LKS_INT_ENB; // interrupt enable

	// init parameters
	frequency.value = 50;
	ltc_enable.value = true;

	// init controller state	
	intr_enable = 0;
	intr_monitor = 0;
}

ltc_c::~ltc_c() {
}

bool ltc_c::on_param_changed(parameter_c *param) {
	// no own parameter or "enable" logic here
	if (param == &frequency) {
		// accept only these
		return (frequency.new_value == 50 || frequency.new_value == 60);
	} else if (param == &priority_slot) {
		intr_request.set_priority_slot(priority_slot.new_value);
	}  else if (param == &intr_level) {
		intr_request.set_level(intr_level.new_value);
	} else if (param == &intr_vector) {
		intr_request.set_vector(intr_vector.new_value);
	}

	return unibusdevice_c::on_param_changed(param); // more actions (for enable)
}

// calc static INTR condition level. 
// Change of that condition calculated by intr_request_c.is_condition_raised() 
// on raising edge.
bool ltc_c::get_intr_signal_level() {
	return intr_monitor && intr_enable;
}

// set status register, and optionally generate INTR
// intr_raise: if inactive->active transition of interrupt condition detected.
void ltc_c::set_lks_dati_value_and_INTR(void) {
	uint16_t val = (intr_monitor ? LKS_INT_MON : 0) | (intr_enable ? LKS_INT_ENB : 0);
	switch (intr_request.edge_detect(get_intr_signal_level())) {
	case intr_request_c::INTERRUPT_EDGE_RAISING:
		// set register atomically with INTR, if INTR not blocked
		unibusadapter->INTR(intr_request, reg_lks, val);
		break;
	case intr_request_c::INTERRUPT_EDGE_FALLING:
		// BR6 is tied to monitor and enable, so raised INTRs may get canceled
		unibusadapter->cancel_INTR(intr_request);
		set_register_dati_value(reg_lks, val, __func__);
		break;
	default:
		set_register_dati_value(reg_lks, val, __func__);
	}
}

// process DATI/DATO access to one of my "active" registers
void ltc_c::on_after_register_access(unibusdevice_register_t *device_reg,
		uint8_t unibus_control) {
	pthread_mutex_lock(&on_after_register_access_mutex);

	if (unibus_control == UNIBUS_CONTROL_DATO) // bus write
		set_register_dati_value(device_reg, device_reg->active_dato_flipflops, __func__);

	switch (device_reg->index) {

	case 0: // LKS
		if (unibus_control == UNIBUS_CONTROL_DATO) { // bus write
			intr_enable = !!(reg_lks->active_dato_flipflops & LKS_INT_ENB);
			intr_monitor = !!(reg_lks->active_dato_flipflops & LKS_INT_MON);
			set_lks_dati_value_and_INTR();
		}
		break;

	default:
		break;
	}
	pthread_mutex_unlock(&on_after_register_access_mutex);

}

void ltc_c::on_power_changed(void) {
	if (power_down) { // power-on defaults
	}
}

// UNIBUS INIT: clear all registers
void ltc_c::on_init_changed(void) {
	// write all registers to "reset-values"
	if (init_asserted) {
		reset_unibus_registers();
		intr_enable = 0;
		intr_monitor = 1;

		intr_request.edge_detect_reset();
		// INFO("ltc_c::on_init()");
	}
}

/* background worker.
 Freqnecy of clock signal edges is tied to system time, not to "wait" periods
 This worker may get delayed arbitray amount of time (as every thread), 
 lost edges are compensated
 */
void ltc_c::worker(unsigned instance) {
	UNUSED(instance); // only one
	timeout_c global_time;
	timeout_c timeout;
	int64_t global_next_edge_ns;

	INFO("KW11 time resolution is < %u us",
			(unsigned )(global_time.get_resolution_ns() / 1000));
	global_time.start_ns(0);
	global_next_edge_ns = global_time.elapsed_ns();
	uint64_t global_edge_count = 0;
	while (!workers_terminate) {

		// signal egde period may change if 50/60 Hz is changed
		uint64_t edge_period_ns = BILLION / (2 * frequency.value);
		uint64_t wait_ns;
		// overdue_ns: time which signal edge is too late
		int64_t overdue_ns = (int64_t) global_time.elapsed_ns() - global_next_edge_ns;
		// INFO does not work on 64 ints
		// printf("elapsed [ms] =%u, overdue [us] =%u\n", (unsigned) global_time.elapsed_ms(), (unsigned) overdue_ns/1000) ;
		// if overdue_ns positive, next signal edge should have occured
		if (overdue_ns < 0) {
			wait_ns = -overdue_ns; // wait until next edge time reached
		} else {
			// time for next signal edge reached
			if (ltc_enable.value) {
				global_edge_count++;
				clock_signal = !clock_signal; // square wave
				if (clock_signal) {
					intr_monitor = 1;
					pthread_mutex_lock(&on_after_register_access_mutex);
					set_lks_dati_value_and_INTR();
					pthread_mutex_unlock(&on_after_register_access_mutex);
				}
			} else
				// clock disconnected
				clock_signal = 0;

			// time of next signal edge
			global_next_edge_ns += edge_period_ns;
			// overdue_ns now time which next signal edge is too late
			overdue_ns -= edge_period_ns;

			if (overdue_ns < 0)
				// next edge now in future: wait exact
				wait_ns = -overdue_ns;
			else
				// next edge still in past:
				// wait shorter than signal edge period to keep up slowly
				wait_ns = edge_period_ns / 2;
			//if ((global_edge_count % 100) == 0)
			//	INFO("LTC: %u secs by edges", (unsigned)(global_edge_count/100) ) ;
		}
		timeout.wait_ns(wait_ns);
	}
}