/******************************************************************************
*  Filename:       systick.h
*  Revised:        2015-11-16 19:41:47 +0100 (Mon, 16 Nov 2015)
*  Revision:       45094
*
*  Description:    Prototypes for the SysTick driver.
*
*  Copyright (c) 2015, Texas Instruments Incorporated
*  All rights reserved.
*
*  Redistribution and use in source and binary forms, with or without
*  modification, are permitted provided that the following conditions are met:
*
*  1) Redistributions of source code must retain the above copyright notice,
*     this list of conditions and the following disclaimer.
*
*  2) Redistributions in binary form must reproduce the above copyright notice,
*     this list of conditions and the following disclaimer in the documentation
*     and/or other materials provided with the distribution.
*
*  3) Neither the name of the ORGANIZATION nor the names of its contributors may
*     be used to endorse or promote products derived from this software without
*     specific prior written permission.
*
*  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
*  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
*  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
*  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
*  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
*  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
*  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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*  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
*  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
*  POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************/

//*****************************************************************************
//
//! \addtogroup system_cpu_group
//! @{
//! \addtogroup systick_api
//! @{
//
//*****************************************************************************

#ifndef __SYSTICK_H__
#define __SYSTICK_H__

//*****************************************************************************
//
// If building with a C++ compiler, make all of the definitions in this header
// have a C binding.
//
//*****************************************************************************
#ifdef __cplusplus
extern "C"
{
#endif

#include <stdbool.h>
#include <stdint.h>
#include <inc/hw_ints.h>
#include <inc/hw_nvic.h>
#include <inc/hw_types.h>
#include <driverlib/debug.h>
#include <driverlib/interrupt.h>

//*****************************************************************************
//
// API Functions and Prototypes
//
//*****************************************************************************

//*****************************************************************************
//
//! \brief Enables the SysTick counter.
//!
//! This will start the SysTick counter. If an interrupt handler has been
//! registered, it will be called when the SysTick counter rolls over.
//!
//! \note Calling this function will cause the SysTick counter to (re)commence
//! counting from its current value. The counter is not automatically reloaded
//! with the period as specified in a previous call to \ref SysTickPeriodSet(). If
//! an immediate reload is required, the NVIC_ST_CURRENT register must be
//! written to force this. Any write to this register clears the SysTick
//! counter to 0 and will cause a reload with the supplied period on the next
//! clock.
//!
//! \return None
//
//*****************************************************************************
__STATIC_INLINE void
SysTickEnable(void)
{
    //
    // Enable SysTick.
    //
    HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_CLK_SRC | NVIC_ST_CTRL_ENABLE;
}

//*****************************************************************************
//
//! \brief Disables the SysTick counter.
//!
//! This will stop the SysTick counter. If an interrupt handler has been
//! registered, it will no longer be called until SysTick is restarted.
//!
//! \return None
//
//*****************************************************************************
__STATIC_INLINE void
SysTickDisable(void)
{
    //
    // Disable SysTick.
    //
    HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_ENABLE);
}

//*****************************************************************************
//
//! \brief Registers an interrupt handler for the SysTick interrupt.
//!
//! This sets the handler to be called when a SysTick interrupt occurs.
//!
//! \param pfnHandler is a pointer to the function to be called when the
//! SysTick interrupt occurs.
//!
//! \return None
//!
//! \sa \ref IntRegister() for important information about registering interrupt
//! handlers.
//
//*****************************************************************************
__STATIC_INLINE void
SysTickIntRegister(void (*pfnHandler)(void))
{
    //
    // Register the interrupt handler, returning an error if an error occurs.
    //
    IntRegister(INT_SYSTICK, pfnHandler);

    //
    // Enable the SysTick interrupt.
    //
    HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
}

//*****************************************************************************
//
//! \brief Unregisters the interrupt handler for the SysTick interrupt.
//!
//! This function will clear the handler to be called when a SysTick interrupt
//! occurs.
//!
//! \return None
//!
//! \sa \ref IntRegister() for important information about registering interrupt
//! handlers.
//
//*****************************************************************************
__STATIC_INLINE void
SysTickIntUnregister(void)
{
    //
    // Disable the SysTick interrupt.
    //
    HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN);

    //
    // Unregister the interrupt handler.
    //
    IntUnregister(INT_SYSTICK);
}

//*****************************************************************************
//
//! \brief Enables the SysTick interrupt.
//!
//! This function will enable the SysTick interrupt, allowing it to be
//! reflected to the processor.
//!
//! \note The SysTick interrupt handler does not need to clear the SysTick
//! interrupt source as this is done automatically by NVIC when the interrupt
//! handler is called.
//!
//! \return None
//
//*****************************************************************************
__STATIC_INLINE void
SysTickIntEnable(void)
{
    //
    // Enable the SysTick interrupt.
    //
    HWREG(NVIC_ST_CTRL) |= NVIC_ST_CTRL_INTEN;
}

//*****************************************************************************
//
//! \brief Disables the SysTick interrupt.
//!
//! This function will disable the SysTick interrupt, preventing it from being
//! reflected to the processor.
//!
//! \return None
//
//*****************************************************************************
__STATIC_INLINE void
SysTickIntDisable(void)
{
    //
    // Disable the SysTick interrupt.
    //
    HWREG(NVIC_ST_CTRL) &= ~(NVIC_ST_CTRL_INTEN);
}

//*****************************************************************************
//
//! \brief Sets the period of the SysTick counter.
//!
//! This function sets the rate at which the SysTick counter wraps; this
//! equals to the number of processor clocks between interrupts.
//!
//! \note Calling this function does not cause the SysTick counter to reload
//! immediately. If an immediate reload is required, the NVIC_ST_CURRENT
//! register must be written. Any write to this register clears the SysTick
//! counter to 0 and will cause a reload with the \c ui32Period supplied here
//! on the next clock after the SysTick is enabled.
//!
//! \param ui32Period is the number of clock ticks in each period of the
//! SysTick counter; must be between 1 and 16,777,216 (0x1000000), both included.
//!
//! \return None
//
//*****************************************************************************
__STATIC_INLINE void
SysTickPeriodSet(uint32_t ui32Period)
{
    //
    // Check the arguments.
    //
    ASSERT((ui32Period > 0) && (ui32Period <= 16777216));

    //
    // Set the period of the SysTick counter.
    //
    HWREG(NVIC_ST_RELOAD) = ui32Period - 1;
}

//*****************************************************************************
//
//! \brief Gets the period of the SysTick counter.
//!
//! This function returns the rate at which the SysTick counter wraps; this
//! equals to the number of processor clocks between interrupts.
//!
//! \return Returns the period of the SysTick counter.
//
//*****************************************************************************
__STATIC_INLINE uint32_t
SysTickPeriodGet(void)
{
    //
    // Return the period of the SysTick counter.
    //
    return(HWREG(NVIC_ST_RELOAD) + 1);
}

//*****************************************************************************
//
//! \brief Gets the current value of the SysTick counter.
//!
//! This function returns the current value of the SysTick counter; this will
//! be a value between the (period - 1) and zero, both included.
//!
//! \return Returns the current value of the SysTick counter
//
//*****************************************************************************
__STATIC_INLINE uint32_t
SysTickValueGet(void)
{
    //
    // Return the current value of the SysTick counter.
    //
    return(HWREG(NVIC_ST_CURRENT));
}

//*****************************************************************************
//
// Mark the end of the C bindings section for C++ compilers.
//
//*****************************************************************************
#ifdef __cplusplus
}
#endif

#endif // __SYSTICK_H__

//*****************************************************************************
//
//! Close the Doxygen group
//! @}
//! @}
//
//*****************************************************************************