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 * $Date: 2016-03-11 11:46:37 -0600 (Fri, 11 Mar 2016) $
 * $Revision: 21839 $
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 ******************************************************************************/

/**
 * @file    prng.h
 * @brief   Pseudo-random number generator(PRNG) driver header file.
 * @note  The PRNG hardware does not produce true random numbers. The output
 *        should be used as a seed to an approved random-number algorithm, per
 *        a certifying authority such as NIST or PCI. The approved algorithm
 *        will output random numbers which are cerfitied for use in encryption
 *        and authentication algorithms.
 */

#ifndef _PRNG_H_
#define _PRNG_H_

/***** Includes *****/
#include "prng_regs.h"

#ifdef __cplusplus
extern "C" {
#endif

/***** Definitions *****/

/***** Globals *****/

/***** Function Prototypes *****/

/**
 * @brief Initialize required clocks and enable PRNG module
 * @note  Function will set divisors to /1 if they are found disabled.
 *        Otherwise, it will not change the divisor.
 */
void PRNG_Init(void);

/**
 * @brief   Returns ready bit to indicates that the PRNG_GetSeed can be called without
 *          being held off. Only needs to be called after POR.
 *
 * @return  0 - PRNG not ready, non-zero = PRNG ready to read
 */
__STATIC_INLINE uint16_t PRNG_Ready(void)
{
    return (MXC_PRNG->user_entropy & MXC_F_PRNG_USER_ENTROPY_RND_NUM_READY);
}

/**
 * @brief Retrieve a seed value from the PRNG
 * @note  The PRNG hardware does not produce true random numbers. The output
 *        should be used as a seed to an approved random-number algorithm, per
 *        a certifying authority such as NIST or PCI. The approved algorithm
 *        will output random numbers which are cerfitied for use in encryption
 *        and authentication algorithms.
 *
 * @return This function returns a 16-bit seed value
 */
__STATIC_INLINE uint16_t PRNG_GetSeed(void)
{
    return MXC_PRNG->rnd_num;
}

/**
 * @brief Add user entropy to the PRNG entropy source
 *
 * @param entropy    This value will be mixed into the PRNG entropy source
 */
__STATIC_INLINE void PRNG_AddUserEntropy(uint8_t entropy)
{
    MXC_PRNG->user_entropy = (uint32_t)entropy;
}

#ifdef __cplusplus
}
#endif

#endif /* _PRNG_H_ */