count_ones
count = count_ones(mask);
uint64_t field_count = count_ones(fields);
uint64_t delimiter_count = count_ones(delimiters);
*parser->file->newlines.tail += count_ones(newlines & (field - 1));
*parser->file->newlines.tail += count_ones(newlines);
count = count_ones(mask);
const uint32_t length = (uint32_t)count_ones(clip_mask) - 1;