add comment to hmac64
@@ -546,6 +546,7 @@ const uint32_t r[] = {7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22
// leftrotate function definition
#define LEFTROTATE(x, c) (((x) << (c)) | ((x) >> (32 - (c))))
+// hmac64 use md5 algorithm without padding, and the result is (c^d .. a^b)
static void
hmac(uint32_t x[2], uint32_t y[2], uint32_t result[2]) {
uint32_t w[16];
