util.h

// Copyright lowRISC contributors (OpenTitan project).
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0
 
#ifndef OPENTITAN_SW_DEVICE_SILICON_CREATOR_LIB_BASE_UTIL_H_
#define OPENTITAN_SW_DEVICE_SILICON_CREATOR_LIB_BASE_UTIL_H_
 
#include <stddef.h>
#include <stdint.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
enum {
  /**
   * Size of an ECDSA P256 signature component in bits.
   */
  kUtilEcdsaP256SignatureComponentBits = 256,
  /**
   * Size of an ECDSA P256 signature component in bytes.
   */
  kUtilEcdsaP256SignatureComponentBytes =
      kUtilEcdsaP256SignatureComponentBits / 8,
  /**
   * Size of an ECDSA P256 signature component in 32b words.
   */
  kUtilEcdsaP256SignatureComponentWords =
      kUtilEcdsaP256SignatureComponentBytes / sizeof(uint32_t),
};
 
/**
 * Rounds up the passed value to get it aligned to the requested number of bits.
 *
 * @param input Value to be rounded up.
 * @param align_bits Number of bits to round the input value to.
 * @return Rounded up value.
 */
uint32_t util_round_up_to(uint32_t input, uint32_t align_bits);
 
/**
 * Compute the number of 32-bit words required to store a number of bytes.
 *
 * @param bytes Buffer of four bytes that represents the ASN1 header.
 * @return Size (in 32-bit words) required to store the input size in bytes.
 */
uint32_t util_size_to_words(uint32_t bytes);
 
/**
 * Reverses a buffer of bytes in place.
 *
 * @param[inout] buf Buffer in little endian order.
 * @param num_bytes Number of bytes in the buffer above.
 */
void util_reverse_bytes(void *buf, size_t num_bytes);
 
/**
 * Fills hexdump of the byte (lowercase).
 *
 * @param byte Byte to convert to a hex string.
 * @param[out] str String buffer (always 2 bytes) to place hex string encoded
 * byte in.
 */
void util_hexdump_byte(uint8_t byte, uint8_t *str);
 
/**
 * Convert the calculated signature (r,s) from little endian to big endian
 *
 * @param r ECDSA signature r value
 * @param s ECDSA signature s value
 */
void util_p256_signature_le_to_be_convert(
    uint32_t r[kUtilEcdsaP256SignatureComponentWords],
    uint32_t s[kUtilEcdsaP256SignatureComponentWords]);
 
#ifdef __cplusplus
}
#endif
 
#endif  // OPENTITAN_SW_DEVICE_SILICON_CREATOR_LIB_BASE_UTIL_H_