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// Example code for running timers in a polling mode
//
// Copyright (C) 2018 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <time.h> // struct timespec
#include <unistd.h> // usleep
#include "autoconf.h" // CONFIG_CLOCK_FREQ
#include "board/irq.h" // irq_disable
#include "board/misc.h" // timer_from_us
#include "board/timer_irq.h" // timer_dispatch_many
#include "command.h" // DECL_CONSTANT
#include "sched.h" // DECL_INIT
// Helper function that returns the system time as a 32bit counter
static uint32_t
get_system_time(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
double t = (double)ts.tv_sec + (double)ts.tv_nsec * .000000001;
return (uint32_t)(t * CONFIG_CLOCK_FREQ);
}
/****************************************************************
* Timers
****************************************************************/
static uint32_t next_wake_time;
// Return the current time (in absolute clock ticks).
uint32_t
timer_read_time(void)
{
return get_system_time();
}
// Activate timer dispatch as soon as possible
void
timer_kick(void)
{
next_wake_time = timer_read_time();
}
// Invoke timers - called below from irq_poll()
static void
do_timer_dispatch(void)
{
next_wake_time = timer_dispatch_many();
}
void
timer_init(void)
{
timer_kick();
}
DECL_INIT(timer_init);
/****************************************************************
* Interrupts
****************************************************************/
// Disable hardware interrupts
void
irq_disable(void)
{
}
// Enable hardware interrupts
void
irq_enable(void)
{
}
// Disable hardware interrupts in not already disabled
irqstatus_t
irq_save(void)
{
return 0;
}
// Restore hardware interrupts to state from flag returned by irq_save()
void
irq_restore(irqstatus_t flag)
{
}
// Atomically enable hardware interrupts and sleep processor until next irq
void
irq_wait(void)
{
// XXX - sleep to prevent excessive cpu usage in simulator
usleep(1);
irq_poll();
}
// Check if an interrupt is active (used only on architectures that do
// not have hardware interrupts)
void
irq_poll(void)
{
uint32_t now = timer_read_time();
if (!timer_is_before(now, next_wake_time))
do_timer_dispatch();
}
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