//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// alarm.c --
//
// Author           : Thierry Delisle
// Created On       : Fri Jun 2 11:31:25 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Fri Jul 21 22:35:18 2017
// Update Count     : 1
//

extern "C" {
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/time.h>
}

#include "libhdr.h"

#include "alarm.h"
#include "kernel_private.h"
#include "preemption.h"

//=============================================================================================
// time type
//=============================================================================================

#define one_second         1_000_000_000ul
#define one_milisecond         1_000_000ul
#define one_microsecond            1_000ul
#define one_nanosecond                 1ul

__cfa_time_t zero_time = { 0 };

void ?{}( __cfa_time_t & this ) { this.val = 0; }
void ?{}( __cfa_time_t & this, zero_t zero ) { this.val = 0; }

void ?{}( itimerval & this, __cfa_time_t * alarm ) {
	this.it_value.tv_sec = alarm->val / one_second;			// seconds
	this.it_value.tv_usec = max( (alarm->val % one_second) / one_microsecond, 1000 ); // microseconds
	this.it_interval.tv_sec = 0;
	this.it_interval.tv_usec = 0;
}


void ?{}( __cfa_time_t & this, timespec * curr ) {
	uint64_t secs  = curr->tv_sec;
	uint64_t nsecs = curr->tv_nsec;
	this.val = (secs * one_second) + nsecs;
}

__cfa_time_t ?=?( __cfa_time_t & this, zero_t rhs ) {
	this.val = 0;
	return this;
}

__cfa_time_t from_s ( uint64_t val ) { __cfa_time_t ret; ret.val = val * 1_000_000_000ul; return ret; }
__cfa_time_t from_ms( uint64_t val ) { __cfa_time_t ret; ret.val = val *     1_000_000ul; return ret; }
__cfa_time_t from_us( uint64_t val ) { __cfa_time_t ret; ret.val = val *         1_000ul; return ret; }
__cfa_time_t from_ns( uint64_t val ) { __cfa_time_t ret; ret.val = val *             1ul; return ret; }

//=============================================================================================
// Clock logic
//=============================================================================================

__cfa_time_t __kernel_get_time() {
	timespec curr;
	clock_gettime( CLOCK_REALTIME, &curr );
	return (__cfa_time_t){ &curr };
}

void __kernel_set_timer( __cfa_time_t alarm ) {
	itimerval val = { &alarm };
	setitimer( ITIMER_REAL, &val, NULL );
}

//=============================================================================================
// Alarm logic
//=============================================================================================

void ?{}( alarm_node_t & this, thread_desc * thrd, __cfa_time_t alarm = zero_time, __cfa_time_t period = zero_time ) {
	this.thrd = thrd;
	this.alarm = alarm;
	this.period = period;
	this.next = 0;
	this.set = false;
	this.kernel_alarm = false;
}

void ?{}( alarm_node_t & this, processor   * proc, __cfa_time_t alarm = zero_time, __cfa_time_t period = zero_time ) {
	this.proc = proc;
	this.alarm = alarm;
	this.period = period;
	this.next = 0;
	this.set = false;
	this.kernel_alarm = true;
}

void ^?{}( alarm_node_t & this ) {
	if( this.set ) {
		unregister_self( &this );
	}
}

LIB_DEBUG_DO( bool validate( alarm_list_t * this ) {
	alarm_node_t ** it = &this->head;
	while( (*it) ) {
		it = &(*it)->next;
	}

	return it == this->tail;
})

static inline void insert_at( alarm_list_t * this, alarm_node_t * n, __alarm_it_t p ) {
	verify( !n->next );
	if( p == this->tail ) {
		this->tail = &n->next;
	}
	else {
		n->next = *p;
	}
	*p = n;

	verify( validate( this ) );
}

void insert( alarm_list_t * this, alarm_node_t * n ) {
	alarm_node_t ** it = &this->head;
	while( (*it) && (n->alarm > (*it)->alarm) ) {
		it = &(*it)->next;
	}

	insert_at( this, n, it );

	verify( validate( this ) );
}

alarm_node_t * pop( alarm_list_t * this ) {
	alarm_node_t * head = this->head;
	if( head ) {
		this->head = head->next;
		if( !head->next ) {
			this->tail = &this->head;
		}
		head->next = NULL;
	}
	verify( validate( this ) );
	return head;
}

static inline void remove_at( alarm_list_t * this, alarm_node_t * n, __alarm_it_t it ) {
	verify( it );
	verify( (*it) == n );

	(*it) = n->next;
	if( !n-> next ) {
		this->tail = it;
	}
	n->next = NULL;

	verify( validate( this ) );
}

static inline void remove( alarm_list_t * this, alarm_node_t * n ) {
	alarm_node_t ** it = &this->head;
	while( (*it) && (*it) != n ) {
		it = &(*it)->next;
	}

	verify( validate( this ) );

	if( *it ) { remove_at( this, n, it ); }

	verify( validate( this ) );
}

void register_self( alarm_node_t * this ) {
	alarm_list_t * alarms = &event_kernel->alarms;

	disable_interrupts();
	lock( &event_kernel->lock DEBUG_CTX2 );
	{
		verify( validate( alarms ) );
		bool first = !alarms->head;

		insert( alarms, this );
		if( first ) {
			__kernel_set_timer( alarms->head->alarm - __kernel_get_time() );
		}
	}
	unlock( &event_kernel->lock );
	this->set = true;
	enable_interrupts( DEBUG_CTX );
}

void unregister_self( alarm_node_t * this ) {
	disable_interrupts();
	lock( &event_kernel->lock DEBUG_CTX2 );
	{
		verify( validate( &event_kernel->alarms ) );
		remove( &event_kernel->alarms, this );
	}
	unlock( &event_kernel->lock );
	enable_interrupts( DEBUG_CTX );
	this->set = false;
}

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