GET_BITS
GET_BITS(BZ_X_MAGIC_4, s->blockSize100k, 8)
GET_BITS(BZ_X_RANDBIT, s->blockRandomised, 1);
GET_BITS(BZ_X_SELECTOR_1, nGroups, 3);
GET_BITS(BZ_X_SELECTOR_2, nSelectors, 15);
GET_BITS(BZ_X_CODING_1, curr, 5);
GET_BITS(lll,uuu,8)
GET_BITS(lll,uuu,1)
GET_BITS(label1, zvec, zn); \