text: /***************************************************************************//**
   * @file
   * @brief General Purpose Cyclic Redundancy Check (GPCRC) API.
   * @version 5.3.3
   *******************************************************************************
   * # License
   * <b>Copyright 2016 Silicon Laboratories, Inc. http://www.silabs.com</b>
   *******************************************************************************
   *
   * Permission is granted to anyone to use this software for any purpose,
   * including commercial applications, and to alter it and redistribute it
   * freely, subject to the following restrictions:
   *
   * 1. The origin of this software must not be misrepresented; you must not
   *    claim that you wrote the original software.
   * 2. Altered source versions must be plainly marked as such, and must not be
   *    misrepresented as being the original software.
   * 3. This notice may not be removed or altered from any source distribution.
   *
   * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no
   * obligation to support this Software. Silicon Labs is providing the
   * Software "AS IS", with no express or implied warranties of any kind,
   * including, but not limited to, any implied warranties of merchantability
   * or fitness for any particular purpose or warranties against infringement
   * of any proprietary rights of a third party.
   *
   * Silicon Labs will not be liable for any consequential, incidental, or
   * special damages, or any other relief, or for any claim by any third party,
   * arising from your use of this Software.
   *
   ******************************************************************************/
  
  #include "em_common.h"
  #include "em_gpcrc.h"
  #include "em_assert.h"
  
  #if defined(GPCRC_PRESENT) && (GPCRC_COUNT > 0)
  
  /***************************************************************************//**
   * @addtogroup emlib
   * @{
   ******************************************************************************/
  
  /***************************************************************************//**
   * @addtogroup GPCRC
   * @{
   ******************************************************************************/
  
  /*******************************************************************************
   ***************************   GLOBAL FUNCTIONS   ******************************
   ******************************************************************************/
  
  /***************************************************************************//**
   * @brief
   *   Initialize the General Purpose Cyclic Redundancy Check (GPCRC) module.
   *
   * @details
   *   Use this function to configure the operational parameters of the GPCRC
   *   such as the polynomial to use and how the input should be preprocessed
   *   before entering the CRC calculation.
   *
   * @note
   *   This function will not copy the init value to the data register in order
   *   to prepare for a new CRC calculation. This must be done by a call
   *   to @ref GPCRC_Start before each calculation, or by using the
   *   autoInit functionality.
   *
   * @param[in] gpcrc
   *   Pointer to GPCRC peripheral register block.
   *
   * @param[in] init
   *   Pointer to initialization structure used to configure the GPCRC.
   ******************************************************************************/
  void GPCRC_Init(GPCRC_TypeDef * gpcrc, const GPCRC_Init_TypeDef * init)
  {
    uint32_t polySelect;
    uint32_t revPoly = 0;
  
    if (init->crcPoly == 0x04C11DB7) {
      polySelect = GPCRC_CTRL_POLYSEL_CRC32;
    } else {
      // If not using the fixed CRC-32 polynomial then we must be using 16-bit
      EFM_ASSERT((init->crcPoly & 0xFFFF0000) == 0);
      polySelect = GPCRC_CTRL_POLYSEL_16;
      revPoly = SL_RBIT16(init->crcPoly);
    }
  
    gpcrc->CTRL = (((uint32_t)init->autoInit << _GPCRC_CTRL_AUTOINIT_SHIFT)
                   | ((uint32_t)init->reverseByteOrder << _GPCRC_CTRL_BYTEREVERSE_SHIFT)
                   | ((uint32_t)init->reverseBits << _GPCRC_CTRL_BITREVERSE_SHIFT)
                   | ((uint32_t)init->enableByteMode << _GPCRC_CTRL_BYTEMODE_SHIFT)
                   | polySelect
                   | ((uint32_t)init->enable << _GPCRC_CTRL_EN_SHIFT));
  
    if (polySelect == GPCRC_CTRL_POLYSEL_16) {
      // Set CRC polynomial value
      gpcrc->POLY = revPoly & _GPCRC_POLY_POLY_MASK;
    }
  
    // Load CRC initialization value to GPCRC_INIT
    gpcrc->INIT = init->initValue;
  }
  
  /***************************************************************************//**
   * @brief
   *   Reset GPCRC registers to the hardware reset state.
   *
   * @note
   *   The data registers are not reset by this function.
   *
   * @param[in] gpcrc
   *   Pointer to GPCRC peripheral register block.
   ******************************************************************************/
  void GPCRC_Reset(GPCRC_TypeDef * gpcrc)
  {
    gpcrc->CTRL = _GPCRC_CTRL_RESETVALUE;
    gpcrc->POLY = _GPCRC_POLY_RESETVALUE;
    gpcrc->INIT = _GPCRC_INIT_RESETVALUE;
  }
  
  /** @} (end addtogroup GPCRC) */
  /** @} (end addtogroup emlib) */
  
  #endif /* defined(GPCRC_COUNT) && (GPCRC_COUNT > 0) */
  