util.c

// Copyright lowRISC contributors (OpenTitan project).
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0
 
#include "sw/device/silicon_creator/lib/base/util.h"
 
uint32_t util_round_up_to(uint32_t input, uint32_t align_bits) {
  uint32_t mask = (1 << align_bits) - 1;
  return (input + mask) & ~mask;
}
 
uint32_t util_size_to_words(uint32_t bytes) {
  return util_round_up_to(bytes, 2) / sizeof(uint32_t);
}
 
void util_reverse_bytes(void *buf, size_t num_bytes) {
  unsigned char temp;
  unsigned char *byte_buf = buf;
  for (size_t i = 0; i < (num_bytes / 2); ++i) {
    temp = byte_buf[i];
    byte_buf[i] = byte_buf[num_bytes - i - 1];
    byte_buf[num_bytes - i - 1] = temp;
  }
}
 
// Returns hexdump character for the half-byte.
static inline uint8_t hexdump_halfbyte(uint8_t half_byte) {
  if (half_byte < 10)
    return '0' + half_byte;
  else
    return 'a' + half_byte - 10;
}
 
void util_hexdump_byte(uint8_t byte, uint8_t *str) {
  str[0] = hexdump_halfbyte((byte & 0xF0) >> 4);
  str[1] = hexdump_halfbyte(byte & 0x0F);
}
 
void util_p256_signature_le_to_be_convert(
    uint32_t r[kUtilEcdsaP256SignatureComponentWords],
    uint32_t s[kUtilEcdsaP256SignatureComponentWords]) {
  util_reverse_bytes(r, kUtilEcdsaP256SignatureComponentBytes);
  util_reverse_bytes(s, kUtilEcdsaP256SignatureComponentBytes);
}