px_systmr.c

/* =============================================================================
     ____    ___    ____    ___    _   _    ___    __  __   ___  __  __ TM
    |  _ \  |_ _|  / ___|  / _ \  | \ | |  / _ \  |  \/  | |_ _| \ \/ /
    | |_) |  | |  | |     | | | | |  \| | | | | | | |\/| |  | |   \  /
    |  __/   | |  | |___  | |_| | | |\  | | |_| | | |  | |  | |   /  \
    |_|     |___|  \____|  \___/  |_| \_|  \___/  |_|  |_| |___| /_/\_\
 
    Copyright (c) 2008 Pieter Conradie <https://piconomix.com>
 
    License: MIT
    https://github.com/piconomix/px-fwlib/blob/master/LICENSE.md
    
    Title:          px_systmr.h : Polled software timers
    Author(s):      Pieter Conradie
    Creation Date:  2008-02-11
 
============================================================================= */
 
/* _____PROJECT INCLUDES_____________________________________________________ */
#include "px_systmr.h"
 
/* _____LOCAL DEFINITIONS____________________________________________________ */
 
/* _____MACROS_______________________________________________________________ */
 
/* _____GLOBAL VARIABLES_____________________________________________________ */
 
/* _____LOCAL VARIABLES______________________________________________________ */
 
/* _____LOCAL FUNCTION DECLARATIONS__________________________________________ */
 
/* _____LOCAL FUNCTIONS______________________________________________________ */
 
/* _____GLOBAL FUNCTIONS_____________________________________________________ */
void px_systmr_start(px_systmr_t * systmr, const px_systmr_ticks_t delay_in_ticks)
{
    // Save delay in case timer is restarted
    systmr->delay_in_ticks = delay_in_ticks;
    // Store start tick
    systmr->start_tick = px_sysclk_get_tick_count();
    // Set state to indicate that timer has started
    systmr->state = PX_SYSTMR_STARTED;
}
 
bool px_systmr_has_started(const px_systmr_t * systmr)
{
    if (systmr->state == PX_SYSTMR_STARTED) 
    {
        return true;
    }
    else
    {
        return false;
    }
}
 
bool px_systmr_has_expired(px_systmr_t * systmr)
{
    px_systmr_ticks_t tick;
    px_systmr_ticks_t start;
    px_systmr_ticks_t end;
 
    // See if timer has been stopped
    if (systmr->state == PX_SYSTMR_STOPPED) 
    {
        return false;
    }
    // See if timer has already expired
    if (systmr->state == PX_SYSTMR_EXPIRED) 
    {
        return true;
    }
    // Timer expire test
    tick = px_sysclk_get_tick_count();
    start = systmr->start_tick;
    end   = systmr->start_tick + systmr->delay_in_ticks;
    if(start < end)
    {
        // |________xxxxxxxxxx__________|
        //          S>>>>>>>>E
        if(  (tick >= start) && (tick < end)  )
        {
            // Timer has not expired yet
            return false;
        }
    }
    else
    {
        // |xxxxxxx__________________xxx|
        //  >>>>>>E                  S>>
        if(  (tick >= start) || (tick < end)  )
        {
            // Timer has not expired yet
            return false;
        }
    }
    // Set state to indicate that timer has expired
    systmr->state = PX_SYSTMR_EXPIRED;
 
    return true;
}
 
void px_systmr_stop(px_systmr_t * systmr)
{
    // Stop timer
    systmr->state = PX_SYSTMR_STOPPED;
}
 
void px_systmr_restart(px_systmr_t * systmr)
{
    // Store start tick
    systmr->start_tick = px_sysclk_get_tick_count();
    // Set state to indicate that timer has started
    systmr->state = PX_SYSTMR_STARTED;
}
 
void px_systmr_reset(px_systmr_t * systmr)
{
    // Calculate and store new start tick
    systmr->start_tick += systmr->delay_in_ticks;
    // Set state to indicate that timer has started
    systmr->state = PX_SYSTMR_STARTED;
}
 
void px_systmr_wait(const px_systmr_ticks_t delay_in_ticks)
{
    px_systmr_t systmr;
 
    px_systmr_start(&systmr, delay_in_ticks);
    while (!px_systmr_has_expired(&systmr))
    {
        ;
    }
}
px_systmr_ticks_t px_systmr_ticks_elapsed(px_systmr_t * systmr)
{
    // Fetch current time
    px_systmr_ticks_t tick          = px_sysclk_get_tick_count();
    px_systmr_ticks_t ticks_elapsed = tick - systmr->start_tick;
 
    return ticks_elapsed;
}