diff options
| author | Yuval Adam <yuv.adm@gmail.com> | 2012-10-29 23:06:01 +0200 |
|---|---|---|
| committer | Yuval Adam <yuv.adm@gmail.com> | 2012-10-29 23:06:01 +0200 |
| commit | 4ba8614c006f9828f0796c140bc3e13c9e67938c (patch) | |
| tree | ad204651c733250d27d20fce8820f9747c43c883 /utils/scheduler.c | |
| parent | e018ceebed74b8223482bc9d1ed0b31c938381da (diff) | |
Added utils
Diffstat (limited to 'utils/scheduler.c')
| -rw-r--r-- | utils/scheduler.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/utils/scheduler.c b/utils/scheduler.c new file mode 100644 index 0000000..82933e1 --- /dev/null +++ b/utils/scheduler.c @@ -0,0 +1,304 @@ +//****************************************************************************
+//
+// scheduler.c - A simple task scheduler
+//
+// Copyright (c) 2010-2012 Texas Instruments Incorporated. All rights reserved.
+// Software License Agreement
+//
+// Texas Instruments (TI) is supplying this software for use solely and
+// exclusively on TI's microcontroller products. The software is owned by
+// TI and/or its suppliers, and is protected under applicable copyright
+// laws. You may not combine this software with "viral" open-source
+// software in order to form a larger program.
+//
+// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
+// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
+// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
+// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
+// DAMAGES, FOR ANY REASON WHATSOEVER.
+//
+// This is part of revision 9453 of the Stellaris Firmware Development Package.
+//
+//****************************************************************************
+#include "inc/hw_types.h"
+#include "inc/hw_ints.h"
+#include "driverlib/systick.h"
+#include "driverlib/sysctl.h"
+#include "driverlib/interrupt.h"
+#include "driverlib/debug.h"
+#include "utils/scheduler.h"
+
+//*****************************************************************************
+//
+//! \addtogroup scheduler_api
+//! @{
+//
+//*****************************************************************************
+
+static volatile unsigned long g_ulSchedulerTickCount;
+
+//****************************************************************************
+//
+//! Handles the SysTick interrupt on behalf of the scheduler module.
+//!
+//! Applications using the scheduler module must ensure that this function is
+//! hooked to the SysTick interrupt vector.
+//!
+//! \return None.
+//
+//****************************************************************************
+void
+SchedulerSysTickIntHandler(void)
+{
+ g_ulSchedulerTickCount++;
+}
+
+//****************************************************************************
+//
+//! Initializes the task scheduler.
+//!
+//! \param ulTicksPerSecond sets the basic frequency of the SysTick interrupt
+//! used by the scheduler to determine when to run the various task functions.
+//!
+//! This function must be called during application startup to configure the
+//! SysTick timer. This is used by the scheduler module to determine when each
+//! of the functions provided in the g_psSchedulerTable array is called.
+//!
+//! The caller is responsible for ensuring that SchedulerSysTickIntHandler()
+//! has previously been installed in the SYSTICK vector in the vector table
+//! and must also ensure that interrupts are enabled at the CPU level.
+//!
+//! Note that this call does not start the scheduler calling the configured
+//! functions. All function calls are made in the context of later calls to
+//! SchedulerRun(). This call merely configures the SysTick interrupt that is
+//! used by the scheduler to determine what the current system time is.
+//!
+//! \return None.
+//
+//****************************************************************************
+void
+SchedulerInit(unsigned long ulTicksPerSecond)
+{
+ ASSERT(ulTicksPerSecond);
+
+ //
+ // Configure SysTick for a periodic interrupt.
+ //
+ SysTickPeriodSet(SysCtlClockGet() / ulTicksPerSecond);
+ SysTickEnable();
+ SysTickIntEnable();
+}
+
+//****************************************************************************
+//
+//! Instructs the scheduler to update its task table and make calls to
+//! functions needing called.
+//!
+//! This function must be called periodically by the client to allow the
+//! scheduler to make calls to any configured task functions if it is their
+//! time to be called. The call must be made at least as frequently as the
+//! most frequent task configured in the g_psSchedulerTable array.
+//!
+//! Although the scheduler makes use of the SysTick interrupt, all calls to
+//! functions configured in \e g_psSchedulerTable are made in the context of
+//! SchedulerRun().
+//!
+//! \return None.
+//
+//****************************************************************************
+void
+SchedulerRun(void)
+{
+ unsigned long ulLoop;
+ tSchedulerTask *psTask;
+
+ //
+ // Loop through each task in the task table.
+ //
+ for(ulLoop = 0; ulLoop < g_ulSchedulerNumTasks; ulLoop++)
+ {
+ //
+ // Get a pointer to the task information.
+ //
+ psTask = &g_psSchedulerTable[ulLoop];
+
+ //
+ // Is this task active and, if so, is it time to call it's function?
+ //
+ if(psTask->bActive && (SchedulerElapsedTicksGet(psTask->ulLastCall) >=
+ psTask->ulFrequencyTicks))
+ {
+ //
+ // Remember the timestamp at which we make the function call.
+ //
+ psTask->ulLastCall = g_ulSchedulerTickCount;
+
+ //
+ // Call the task function, passing the provided parameter.
+ //
+ psTask->pfnFunction(psTask->pvParam);
+ }
+ }
+}
+
+//****************************************************************************
+//
+//! Enables a task and allows the scheduler to call it periodically.
+//!
+//! \param ulIndex is the index of the task which is to be enabled in the
+//! global \e g_psSchedulerTable array.
+//! \param bRunNow is \b true if the task is to be run on the next call to
+//! SchedulerRun() or \b false if one whole period is to elapse before
+//! the task is run.
+//!
+//! This function marks one of the configured tasks as enabled and causes
+//! SchedulerRun() to call that task periodically. The caller may choose to
+//! have the enabled task run for the first time on the next call to
+//! SchedulerRun() or to wait one full task period before making the first
+//! call.
+//!
+//! \return None.
+//
+//****************************************************************************
+void
+SchedulerTaskEnable(unsigned long ulIndex, tBoolean bRunNow)
+{
+ //
+ // Is the task index passed valid?
+ //
+ if(ulIndex < g_ulSchedulerNumTasks)
+ {
+ //
+ // Yes - mark the task as active.
+ //
+ g_psSchedulerTable[ulIndex].bActive = true;
+
+ //
+ // Set the last call time to ensure that the function is called either
+ // next time the scheduler is run or after the desired number of ticks
+ // depending upon the value of the bRunNow parameter.
+ //
+ if(bRunNow)
+ {
+ //
+ // Cause the task to run on the next call to SchedulerRun().
+ //
+ g_psSchedulerTable[ulIndex].ulLastCall = (g_ulSchedulerTickCount -
+ g_psSchedulerTable[ulIndex].ulFrequencyTicks);
+ }
+ else
+ {
+ //
+ // Cause the task to run after one full time period.
+ //
+ g_psSchedulerTable[ulIndex].ulLastCall = g_ulSchedulerTickCount;
+ }
+ }
+}
+
+//****************************************************************************
+//
+//! Disables a task and prevents the scheduler from calling it.
+//!
+//! \param ulIndex is the index of the task which is to be disabled in the
+//! global \e g_psSchedulerTable array.
+//!
+//! This function marks one of the configured tasks as inactive and prevents
+//! SchedulerRun() from calling it. The task may be reenabled by calling
+//! SchedulerTaskEnable().
+//!
+//! \return None.
+//
+//****************************************************************************
+void
+SchedulerTaskDisable(unsigned long ulIndex)
+{
+ //
+ // Is the task index passed valid?
+ //
+ if(ulIndex < g_ulSchedulerNumTasks)
+ {
+ //
+ // Yes - mark the task as inactive.
+ //
+ g_psSchedulerTable[ulIndex].bActive = false;
+ }
+}
+
+//****************************************************************************
+//
+//! Returns the current system time in ticks since power on.
+//!
+//! This function may be called by a client to retrieve the current system
+//! time. The value returned is a count of ticks elapsed since the system
+//! last booted.
+//!
+//! \return Tick count since last boot.
+//
+//****************************************************************************
+unsigned long
+SchedulerTickCountGet(void)
+{
+ return(g_ulSchedulerTickCount);
+}
+
+//****************************************************************************
+//
+//! Returns the number of ticks elapsed since the provided tick count.
+//!
+//! \param ulTickCount is the tick count from which to determine the elapsed
+//! time.
+//!
+//! This function may be called by a client to determine how much time has
+//! passed since a particular tick count provided in the \e ulTickCount
+//! parameter. This function takes into account wrapping of the global tick
+//! counter and assumes that the provided tick count always represents a time
+//! in the past. The returned value will, of course, be wrong if the tick
+//! counter has wrapped more than once since the passed \e ulTickCount. As a
+//! result, please do not use this function if you are dealing with timeouts
+//! of 497 days or longer (assuming you use a 10mS tick period).
+//!
+//! \return The number of ticks elapsed since the provided tick count.
+//
+//****************************************************************************
+unsigned long
+SchedulerElapsedTicksGet(unsigned long ulTickCount)
+{
+ //
+ // Determine the calculation based upon whether the global tick count has
+ // wrapped since the passed ulTickCount.
+ //
+ return(SchedulerElapsedTicksCalc(ulTickCount, g_ulSchedulerTickCount));
+}
+
+//****************************************************************************
+//
+//! Returns the number of ticks elapsed between two times.
+//!
+//! \param ulTickStart is the system tick count for the start of the period.
+//! \param ulTickEnd is the system tick count for the end of the period.
+//!
+//! This function may be called by a client to determine the number of ticks
+//! which have elapsed between provided starting and ending tick counts. The
+//! function takes into account wrapping cases where the end tick count is
+//! lower than the starting count assuming that the ending tick count always
+//! represents a later time than the starting count.
+//!
+//! \return The number of ticks elapsed between the provided start and end
+//! counts.
+//
+//****************************************************************************
+unsigned long
+SchedulerElapsedTicksCalc(unsigned long ulTickStart, unsigned long ulTickEnd)
+{
+ return((ulTickEnd > ulTickStart) ? (ulTickEnd - ulTickStart) :
+ ((0xFFFFFFFF - ulTickStart) + ulTickEnd + 1));
+}
+
+//*****************************************************************************
+//
+// Close the Doxygen group.
+//! @}
+//
+//*****************************************************************************
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