hex_lib.c

/*
 ============================================================================
 Name        : hex_lib.c
 Author      : Afroz Mohiuddin
 Version     : 1
 Description : Hexadecimal libraries.
 ============================================================================
 */

#include "hex_lib.h"
#include "macros.h"

static int32_t hex_to_int_array[16][16] = {
  {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
  {16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31},
  {32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47},
  {48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63},
  {64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79},
  {80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95},
  {96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111},
  {112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127},
  {128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143},
  {144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159},
  {160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175},
  {176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191},
  {192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207},
  {208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223},
  {224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239},
  {240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255}
};

char lower_half(char input_byte) {
  return input_byte & 0x0F;
}

char higher_half(char input_byte) {
  return (input_byte & 0xF0) >> 4;
}

int32_t hex_alphabet_to_int(char hex_char) {
  switch (hex_char) {
    case 0x0:
      return 0;
    case 0x1:
      return 1;
    case 0x2:
      return 2;
    case 0x3:
      return 3;
    case 0x4:
      return 4;
    case 0x5:
      return 5;
    case 0x6:
      return 6;
    case 0x7:
      return 7;
    case 0x8:
      return 8;
    case 0x9:
      return 9;
    case 0xA:
      return 10;
    case 0xB:
      return 11;
    case 0xC:
      return 12;
    case 0xD:
      return 13;
    case 0xE:
      return 14;
    case 0xF:
      return 15;
  }
  LOG_FATAL("%c didn't match anything!", hex_char);
  return -1;
}

int32_t hex_char_to_int(char hex_char) {
  int32_t return_value = 0;
  char higher_half_char = higher_half(hex_char);
  char lower_half_char = lower_half(hex_char);
  return hex_to_int_array[hex_alphabet_to_int(higher_half_char)]
                         [hex_alphabet_to_int(lower_half_char)];
}

int32_t hex_array_to_int(char* byte_array, int32_t length) {
  int32_t return_value = 0;
  int32_t index = 0;
  while (index < length) {
    return_value <<= 8;
    return_value += hex_char_to_int(byte_array[index++]);
  }
  return return_value;
}