gnrc_netif_addr_from_str.c
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/*
* Copyright (C) 2015 Martine Lenders <mlenders@inf.fu-berlin.de>
* Copyright (C) 2015 René Kijewski <rene.kijewski@fu-berlin.de>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @{
*
* @file
*/
#include "net/gnrc/netif.h"
static inline int _dehex(char c, int default_)
{
if ('0' <= c && c <= '9') {
return c - '0';
}
else if ('A' <= c && c <= 'F') {
return c - 'A' + 10;
}
else if ('a' <= c && c <= 'f') {
return c - 'a' + 10;
}
else {
return default_;
}
}
size_t gnrc_netif_addr_from_str(uint8_t *out, size_t out_len, const char *str)
{
/* Walk over str from the end. */
/* Take two chars a time as one hex value (%hhx). */
/* Leading zeros can be omitted. */
/* Every non-hexadimal character is a delimiter. */
/* Leading, tailing and adjacent delimiters are forbidden. */
const char *end_str = str;
uint8_t *out_end = out;
size_t count = 0;
int assert_cell = 1;
if (!str || !*str) {
return 0;
}
while (end_str[1]) {
++end_str;
}
while (end_str >= str) {
int a = 0, b = _dehex(*end_str--, -1);
if (b < 0) {
if (assert_cell) {
return 0;
}
else {
assert_cell = 1;
continue;
}
}
assert_cell = 0;
if (end_str >= str) {
a = _dehex(*end_str--, 0);
}
if (++count > out_len) {
return 0;
}
*out_end++ = (a << 4) | b;
}
if (assert_cell) {
return 0;
}
/* out is reversed */
while (out < --out_end) {
uint8_t tmp = *out_end;
*out_end = *out;
*out++ = tmp;
}
return count;
}
/** @} */