BITS_IN_SIZE_T
for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {