text: /******************************************************************************
  *  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
  *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  *  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
  //! @}
  //! @}
  //
  //*****************************************************************************
  