tools/gen_ethaddr_crc.c

   1 /*
   2  * (C) Copyright 2016
   3  * Olliver Schinagl <oliver@schinagl.nl>
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <ctype.h>
   9 #include <stdint.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <u-boot/crc.h>
  14
  15 #define ARP_HLEN 6 /* Length of hardware address */
  16 #define ARP_HLEN_ASCII (ARP_HLEN * 2) + (ARP_HLEN - 1) /* with separators */
  17 #define ARP_HLEN_LAZY (ARP_HLEN * 2) /* separatorless hardware address length */
  18
  19 uint8_t nibble_to_hex(const char *nibble, bool lo)
  20 {
  21         return (strtol(nibble, NULL, 16) << (lo ? 0 : 4)) & (lo ? 0x0f : 0xf0);
  22 }
  23
  24 int process_mac(const char *mac_address)
  25 {
  26         uint8_t ethaddr[ARP_HLEN + 1] = { 0x00 };
  27         uint_fast8_t i = 0;
  28
  29         while (*mac_address != '\0') {
  30                 char nibble[2] = { 0x00, '\n' }; /* for strtol */
  31
  32                 nibble[0] = *mac_address++;
  33                 if (isxdigit(nibble[0])) {
  34                         if (isupper(nibble[0]))
  35                                 nibble[0] = tolower(nibble[0]);
  36                         ethaddr[i >> 1] |= nibble_to_hex(nibble, (i % 2) != 0);
  37                         i++;
  38                 }
  39         }
  40
  41         for (i = 0; i < ARP_HLEN; i++)
  42                 printf("%.2x", ethaddr[i]);
  43         printf("%.2x\n", crc8(0, ethaddr, ARP_HLEN));
  44
  45         return 0;
  46 }
  47
  48 void print_usage(char *cmdname)
  49 {
  50         printf("Usage: %s <mac_address>\n", cmdname);
  51         puts("<mac_address> may be with or without separators.");
  52         puts("Valid seperators are ':' and '-'.");
  53         puts("<mac_address> digits are in base 16.\n");
  54 }
  55
  56 int main(int argc, char *argv[])
  57 {
  58         if (argc < 2) {
  59                 print_usage(argv[0]);
  60                 return 1;
  61         }
  62
  63         if (!((strlen(argv[1]) == ARP_HLEN_ASCII) || (strlen(argv[1]) == ARP_HLEN_LAZY))) {
  64                 puts("The MAC address is not valid.\n");
  65                 print_usage(argv[0]);
  66                 return 1;
  67         }
  68
  69         if (process_mac(argv[1])) {
  70                 puts("Failed to calculate the MAC's checksum.");
  71                 return 1;
  72         }
  73
  74         return 0;
  75 }