/* utils.h - TinyCrypt interface to platform-dependent run-time operations */

/*
    Copyright (C) 2017 by Intel Corporation, All Rights Reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

      - Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.

      - 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.

      - Neither the name of Intel Corporation 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 OWNER 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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    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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*/

/**
    @file
    @brief Interface to platform-dependent run-time operations.

*/

#ifndef __TC_UTILS_H__
#define __TC_UTILS_H__

#include <stdint.h>
#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
    @brief Copy the the buffer 'from' to the buffer 'to'.
    @return returns TC_CRYPTO_SUCCESS (1)
           returns TC_CRYPTO_FAIL (0) if:
                  from_len > to_len.

    @param to OUT -- destination buffer
    @param to_len IN -- length of destination buffer
    @param from IN -- origin buffer
    @param from_len IN -- length of origin buffer
*/
unsigned int _copy(uint8_t* to, unsigned int to_len,
                   const uint8_t* from, unsigned int from_len);

/**
    @brief Set the value 'val' into the buffer 'to', 'len' times.

    @param to OUT -- destination buffer
    @param val IN -- value to be set in 'to'
    @param len IN -- number of times the value will be copied
*/
void _set(void* to, uint8_t val, unsigned int len);

/*
    @brief AES specific doubling function, which utilizes
    the finite field used by AES.
    @return Returns a^2

    @param a IN/OUT -- value to be doubled
*/
uint8_t _double_byte(uint8_t a);

/*
    @brief Constant-time algorithm to compare if two sequences of bytes are equal
    @return Returns 0 if equal, and non-zero otherwise

    @param a IN -- sequence of bytes a
    @param b IN -- sequence of bytes b
    @param size IN -- size of sequences a and b
*/
int _compare(const uint8_t* a, const uint8_t* b, size_t size);

#ifdef __cplusplus
}
#endif

#endif /* __TC_UTILS_H__ */
