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/*
ChibiOS/GFX - Copyright (C) 2012
Joel Bodenmann aka Tectu <joel@unormal.org>
This file is part of ChibiOS/GFX.
ChibiOS/GFX is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/GFX is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file include/gtimer/gtimer.h
* @brief GTIMER GFX User Timer subsystem header file.
*
* @addtogroup GTIMER
*
* @details The reason why ChibiOS/GFX has it's own timer abstraction is because
* virtual timers provided by ChibiOS/RT are interrupt context only.
* While great for what they are designed for, they make coding of the input
* drivers much more complex.
* For non-performance critical drivers like these input drivers, it would also
* hog an in-ordinate amount of critical (interrupt locked) system time.
* This contrary to the goals of a real-time operating system. So a user-land
* (thread based) timer mechanism is also required.
*
* @pre GFX_USE_GTIMER must be set to TRUE in your gfxconf.h
*
* @{
*/
#ifndef _GTIMER_H
#define _GTIMER_H
#include "gfx.h"
#if GFX_USE_GTIMER || defined(__DOXYGEN__)
/*===========================================================================*/
/* Type definitions */
/*===========================================================================*/
/* Data part of a static GTimer initialiser */
#define _GTIMER_DATA() {0,0,0,0,0,0,0}
/* Static GTimer initialiser */
#define GTIMER_DECL(name) GTimer name = _GTIMER_DATA()
/* A callback function (executed in a thread context) */
typedef void (*GTimerFunction)(void *param);
/**
* @brief A GTimer structure
*/
typedef struct GTimer_t {
GTimerFunction fn;
void *param;
systime_t when;
systime_t period;
uint16_t flags;
struct GTimer_t *next;
struct GTimer_t *prev;
} GTimer;
/*===========================================================================*/
/* External declarations. */
/*===========================================================================*/
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Initialise a timer.
*
* @param[in] pt pointer to a GTimer structure
*
* @api
*/
void gtimerInit(GTimer *pt);
/**
* @brief Set a timer going or alter its properties if it is already going.
*
* @param[in] pt Pointer to a GTimer structure
* @param[in] fn The callback function
* @param[in] param The parameter to pass to the callback function
* @param[in] periodic Is the timer a periodic timer? FALSE is a once-only timer.
* @param[in] millisec The timer period. The following special values are allowed:
* TIME_IMMEDIATE causes the callback function to be called asap.
* A periodic timer with this value will fire once only.
* TIME_INFINITE never timeout (unless triggered by gtimerJab or gtimerJabI)
*
* @note If the timer is already active its properties are updated with the new parameters.
* The current period will be immediately canceled (without the callback function being
* called) and the timer will be restart with the new timer properties.
* @note The callback function should be careful not to over-run the thread stack.
* Define a new value for the macro GTIME_THREAD_STACK_SIZE if you want to
* change the default size.
* @note The callback function should return as quickly as possible as all
* timer callbacks are performed by a single thread. If a callback function
* takes too long it could affect the timer response for other timers.
* @note A timer callback function is not a replacement for a dedicated thread if the
* function wants to perform computationally expensive stuff.
* @note As the callback function is called on GTIMER's thread, the function must make sure it uses
* appropriate synchronisation controls such as semaphores or mutexes around any data
* structures it shares with other threads such as the main application thread.
*
* @api
*/
void gtimerStart(GTimer *pt, GTimerFunction fn, void *param, bool_t periodic, systime_t millisec);
/**
* @brief Stop a timer (periodic or otherwise)
*
* @param[in] pt Pointer to a GTimer structure
*
* @note If the timer is not active this does nothing.
*
* @api
*/
void gtimerStop(GTimer *pt);
/**
* @brief Test if a timer is currently active
*
* @param[in] pt Pointer to a GTimer structure
*
* @return TRUE if active, FALSE otherwise
*
* @api
*/
bool_t gtimerIsActive(GTimer *pt);
/**
* @brief Jab a timer causing the current period to immediate expire
* @details The callback function will be called as soon as possible.
*
* @pre Use from a normal thread context.
*
* @param[in] pt Pointer to a GTimer structure
*
* @note If the timer is not active this does nothing.
* @note Repeated Jabs before the callback function actually happens are ignored.
*
* @api
*/
void gtimerJab(GTimer *pt);
/**
* @brief Jab a timer causing the current period to immediate expire
* @details The callback function will be called as soon as possible.
*
* @pre Use from an interrupt routine context.
*
* @param[in] pt Pointer to a GTimer structure
*
* @note If the timer is not active this does nothing.
* @note Repeated Jabs before the callback function actually happens are ignored.
*
* @iclass
* @api
*/
void gtimerJabI(GTimer *pt);
#ifdef __cplusplus
}
#endif
#endif /* GFX_USE_GTIMER */
#endif /* _GTIMER_H */
/** @} */
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