GNUmifluz: P_32_SWAP

{ \
 u_int32_t _tmp; \
 P_32_COPY(a, &_tmp); \
 ((u_int8_t *)a)[0] = ((u_int8_t *)&_tmp)[3]; \
 ((u_int8_t *)a)[1] = ((u_int8_t *)&_tmp)[2]; \
 ((u_int8_t *)a)[2] = ((u_int8_t *)&_tmp)[1]; \
 ((u_int8_t *)a)[3] = ((u_int8_t *)&_tmp)[0]; \
}