++/* Implement both __sync_<op>_and_fetch and __sync_fetch_and_<op> for
++   subword-sized quantities.  */
++
++#define SUBWORD_SYNC_OP(OP, PFX_OP, INF_OP, TYPE, WIDTH, RETURN)      \
++  TYPE HIDDEN                                                         \
++  NAME##_##RETURN (OP, WIDTH) (TYPE *ptr, TYPE val)                   \
++  {                                                                   \
++    int *wordptr = (int *) ((unsigned int) ptr & ~3);                 \
++    unsigned int mask, shift, oldval, newval;                         \
++    int failure;                                                      \
++                                                                      \
++    shift = (((unsigned int) ptr & 3) << 3) ^ INVERT_MASK_##WIDTH;    \
++    mask = MASK_##WIDTH << shift;                                     \
++                                                                      \
++    do {                                                              \
++      oldval = *wordptr;                                              \
++      newval = ((PFX_OP ((oldval & mask) >> shift)                    \
++                 INF_OP (unsigned int) val) << shift) & mask;         \
++      newval |= oldval & ~mask;
++      failure = __kernel_cmpxchg (oldval, newval, wordptr);           \
++    } while (failure != 0);                                           \
++                                                                      \
++    return (RETURN & mask) >> shift;                                  \
++  }