+
+/**
+ * Convert a string of hexadecimal pairs into its binary
+ * representation.
+ *
+ * @param[out] bin Buffer to store binary representation. The buffer size must
+ * be at least @p count.
+ * @param[in] hex String with hexadecimal pairs to convert into its binary
+ * representation.
+ * @param[in] count Number of hexadecimal pairs to convert.
+ *
+ * @return The number of converted hexadecimal pairs.
+ */
+size_t unhexify(uint8_t *bin, const char *hex, size_t count)
+{
+ size_t i;
+ char tmp;
+
+ if (!bin || !hex)
+ return 0;
+
+ memset(bin, 0, count);
+
+ for (i = 0; i < 2 * count; i++) {
+ if (hex[i] >= 'a' && hex[i] <= 'f')
+ tmp = hex[i] - 'a' + 10;
+ else if (hex[i] >= 'A' && hex[i] <= 'F')
+ tmp = hex[i] - 'A' + 10;
+ else if (hex[i] >= '0' && hex[i] <= '9')
+ tmp = hex[i] - '0';
+ else
+ return i / 2;
+
+ bin[i / 2] |= tmp << (4 * ((i + 1) % 2));
+ }
+
+ 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;
+
+ return i;
+}
+
+void buffer_shr(void *_buf, unsigned buf_len, unsigned count)
+{
+ unsigned i;
+ unsigned char *buf = _buf;
+ unsigned bytes_to_remove;
+ unsigned shift;
+
+ bytes_to_remove = count / 8;
+ shift = count - (bytes_to_remove * 8);
+
+ for (i = 0; i < (buf_len - 1); i++)
+ buf[i] = (buf[i] >> shift) | ((buf[i+1] << (8 - shift)) & 0xff);
+
+ buf[(buf_len - 1)] = buf[(buf_len - 1)] >> shift;
+
+ if (bytes_to_remove) {
+ memmove(buf, &buf[bytes_to_remove], buf_len - bytes_to_remove);
+ memset(&buf[buf_len - bytes_to_remove], 0, bytes_to_remove);
+ }
+}