+ return i / 2;
+}
+
+/**
+ * Convert binary data into a string of hexadecimal pairs.
+ *
+ * @param[out] hex Buffer to store string of hexadecimal pairs. The buffer size
+ * must be at least @p length.
+ * @param[in] bin Buffer with binary data to convert into hexadecimal pairs.
+ * @param[in] count Number of bytes to convert.
+ * @param[in] length Maximum number of characters, including null-terminator,
+ * to store into @p hex.
+ *
+ * @returns The length of the converted string excluding null-terminator.
+ */
+size_t hexify(char *hex, const uint8_t *bin, size_t count, size_t length)
+{
+ size_t i;
+ uint8_t tmp;
+
+ if (!length)
+ return 0;
+
+ for (i = 0; i < length - 1 && i < 2 * count; i++) {
+ tmp = (bin[i / 2] >> (4 * ((i + 1) % 2))) & 0x0f;
+ hex[i] = hex_digits[tmp];
+ }
+
+ hex[i] = 0;
+