WORDBYTES
if (bufend - end >= (ptrdiff_t)(WORDBYTES - 1)) {
if (offset >= WORDBYTES) {
src += WORDBYTES;
dst += WORDBYTES;
src += WORDBYTES;
dst += WORDBYTES;
src += WORDBYTES;
dst += WORDBYTES;
v |= v << ((WORDBYTES == 8) ? 32 : 0);