/*
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2019 Sensnology AB
 * Full contributor list: https://github.com/mysensors/MySensors/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

//This may be used to change user task stack size:
//#define CONT_STACKSIZE 4096
#include <Arduino.h>
#include "Schedule.h"
extern "C" {
#include "ets_sys.h"
#include "os_type.h"
#include "osapi.h"
#include "mem.h"
#include "user_interface.h"
#include "cont.h"
}
#include <core_version.h>
#include "gdb_hooks.h"

#define LOOP_TASK_PRIORITY 1
#define LOOP_QUEUE_SIZE    1
#define OPTIMISTIC_YIELD_TIME_US 16000

extern "C" void call_user_start();
extern void loop();
extern void setup();
extern void(*__init_array_start)(void);
extern void(*__init_array_end)(void);

/* Not static, used in Esp.cpp */
struct rst_info resetInfo;

/* Not static, used in core_esp8266_postmortem.c and other places.
 * Placed into noinit section because we assign value to this variable
 * before .bss is zero-filled, and need to preserve the value.
 */
cont_t* g_pcont __attribute__((section(".noinit")));

/* Event queue used by the main (arduino) task */
static os_event_t s_loop_queue[LOOP_QUEUE_SIZE];

/* Used to implement optimistic_yield */
static uint32_t s_micros_at_task_start;

/* For ets_intr_lock_nest / ets_intr_unlock_nest
 * Max nesting seen by SDK so far is 2.
 */
#define ETS_INTR_LOCK_NEST_MAX 7
static uint16_t ets_intr_lock_stack[ETS_INTR_LOCK_NEST_MAX];
static byte     ets_intr_lock_stack_ptr = 0;


extern "C" {
	extern const uint32_t __attribute__((section(".ver_number"))) core_version =
	    ARDUINO_ESP8266_GIT_VER;
	const char* core_release =
#ifdef ARDUINO_ESP8266_RELEASE
	    ARDUINO_ESP8266_RELEASE;
#else
	    NULL;
#endif
} // extern "C"

void initVariant() __attribute__((weak));
void initVariant()
{
}

void preloop_update_frequency() __attribute__((weak));
void preloop_update_frequency()
{
#if defined(F_CPU) && (F_CPU == 160000000L)
	REG_SET_BIT(0x3ff00014, BIT(0));
	ets_update_cpu_frequency(160);
#endif
}

extern "C" bool can_yield()
{
	return cont_can_yield(g_pcont);
}

static inline void esp_yield_within_cont() __attribute__((always_inline));
static void esp_yield_within_cont()
{
	cont_yield(g_pcont);
	run_scheduled_recurrent_functions();
}

extern "C" void esp_yield()
{
	if (can_yield()) {
		esp_yield_within_cont();
	}
}

extern "C" void esp_schedule()
{
	// always on CONT stack here
	ets_post(LOOP_TASK_PRIORITY, 0, 0);
}

extern "C" void __yield()
{
	if (can_yield()) {
		esp_schedule();
		esp_yield_within_cont();
	} else {
		panic();
	}
}

extern "C" void yield(void) __attribute__((weak, alias("__yield")));

extern "C" void optimistic_yield(uint32_t interval_us)
{
	if (can_yield() &&
	        (system_get_time() - s_micros_at_task_start) > interval_us) {
		yield();
	}
}


// Replace ets_intr_(un)lock with nestable versions
extern "C" void IRAM_ATTR ets_intr_lock()
{
	if (ets_intr_lock_stack_ptr < ETS_INTR_LOCK_NEST_MAX) {
		ets_intr_lock_stack[ets_intr_lock_stack_ptr++] = xt_rsil(3);
	} else {
		xt_rsil(3);
	}
}

extern "C" void IRAM_ATTR ets_intr_unlock()
{
	if (ets_intr_lock_stack_ptr > 0) {
		xt_wsr_ps(ets_intr_lock_stack[--ets_intr_lock_stack_ptr]);
	} else {
		xt_rsil(0);
	}
}


// Save / Restore the PS state across the rom ets_post call as the rom code
// does not implement this correctly.
extern "C" bool ets_post_rom(uint8 prio, ETSSignal sig, ETSParam par);

extern "C" bool IRAM_ATTR ets_post(uint8 prio, ETSSignal sig, ETSParam par)
{
	uint32_t saved;
	asm volatile ("rsr %0,ps":"=a" (saved));
	bool rc = ets_post_rom(prio, sig, par);
	xt_wsr_ps(saved);
	return rc;
}

extern "C" void __loop_end(void)
{
	run_scheduled_functions();
	run_scheduled_recurrent_functions();
}

extern "C" void loop_end(void) __attribute__((weak, alias("__loop_end")));

static void loop_wrapper()
{
	static bool setup_done = false;
	preloop_update_frequency();
	if (!setup_done) {
		_begin();		// Startup MySensors library
		setup_done = true;
	}
	_process();			// Process incoming data
	loop();
	run_scheduled_functions();
	esp_schedule();
}

static void loop_task(os_event_t *events)
{
	(void)events;
	s_micros_at_task_start = system_get_time();
	cont_run(g_pcont, &loop_wrapper);
	if (cont_check(g_pcont) != 0) {
		panic();
	}
}
extern "C" {

	struct object {
		long placeholder[10];
	};
	void __register_frame_info(const void *begin, struct object *ob);
	extern char __eh_frame[];
}

static void do_global_ctors(void)
{
	static struct object ob;
	__register_frame_info(__eh_frame, &ob);

	void(**p)(void) = &__init_array_end;
	while (p != &__init_array_start) {
		(*--p)();
	}
}

extern "C" {
	extern void __unhandled_exception(const char *str);

	static void  __unhandled_exception_cpp()
	{
#ifndef __EXCEPTIONS
		abort();
#else
		static bool terminating;
		if (terminating) {
			abort();
		}
		terminating = true;
		/* Use a trick from vterminate.cc to get any std::exception what() */
		try {
			__throw_exception_again;
		} catch (const std::exception& e) {
			__unhandled_exception(e.what());
		} catch (...) {
			__unhandled_exception("");
		}
#endif
	}

}

void init_done()
{
	system_set_os_print(1);
	gdb_init();
	std::set_terminate(__unhandled_exception_cpp);
	do_global_ctors();
	esp_schedule();
}

/* This is the entry point of the application.
 * It gets called on the default stack, which grows down from the top
 * of DRAM area.
 * .bss has not been zeroed out yet, but .data and .rodata are in place.
 * Cache is not enabled, so only ROM and IRAM functions can be called.
 * Peripherals (except for SPI0 and UART0) are not initialized.
 * This function does not return.
 */
/*
	A bit of explanation for this entry point:

	SYS is the SDK task/context used by the upperlying system to run its
	administrative tasks (at least WLAN and lwip's receive callbacks and
	Ticker).  NONOS-SDK is designed to run user's non-threaded code in
	another specific task/context with its own stack in BSS.

	Some clever fellows found that the SYS stack was a large and quite unused
	piece of ram that we could use for the user's stack instead of using user's
	main memory, thus saving around 4KB on ram/heap.

	A problem arose later, which is that this stack can heavily be used by
	the SDK for some features.  One of these features is WPS.  We still don't
	know if other features are using this, or if this memory is going to be
	used in future SDK releases.

	WPS beeing flawed by its poor security, or not beeing used by lots of
	users, it has been decided that we are still going to use that memory for
	user's stack and disable the use of WPS.

	app_entry() jumps to app_entry_custom() defined as "weakref" calling
	itself a weak customizable function, allowing to use another one when
	this is required (see core_esp8266_app_entry_noextra4k.cpp, used by WPS).

	(note: setting app_entry() itself as "weak" is not sufficient and always
	 ends up with the other "noextra4k" one linked, maybe because it has a
	 default ENTRY(app_entry) value in linker scripts).

	References:
	https://github.com/esp8266/Arduino/pull/4553
	https://github.com/esp8266/Arduino/pull/4622
	https://github.com/esp8266/Arduino/issues/4779
	https://github.com/esp8266/Arduino/pull/4889

*/

extern "C" void app_entry_redefinable(void) __attribute__((weak));
extern "C" void app_entry_redefinable(void)
{
	/* Allocate continuation context on this SYS stack,
		 and save pointer to it. */
	cont_t s_cont __attribute__((aligned(16)));
	g_pcont = &s_cont;

	/* Call the entry point of the SDK code. */
	call_user_start();
}

static void app_entry_custom(void) __attribute__((weakref("app_entry_redefinable")));

extern "C" void app_entry(void)
{
	return app_entry_custom();
}

extern "C" void preinit(void) __attribute__((weak));
extern "C" void preinit(void)
{
	/* do nothing by default */
}

extern "C" void user_init(void)
{
	struct rst_info *rtc_info_ptr = system_get_rst_info();
	memcpy((void *)&resetInfo, (void *)rtc_info_ptr, sizeof(resetInfo));

	uart_div_modify(0, UART_CLK_FREQ / (115200));

	init(); // in core_esp8266_wiring.c, inits hw regs and sdk timer

	initVariant();

	cont_init(g_pcont);

	preinit(); // Prior to C++ Dynamic Init (not related to above init() ). Meant to be user redefinable.

	ets_task(loop_task,
	         LOOP_TASK_PRIORITY, s_loop_queue,
	         LOOP_QUEUE_SIZE);

	system_init_done_cb(&init_done);
}
