NX_MAX
free_space = NX_MAX(0, fifo_free_bytes(used_in, fifo_in_len)
int target_max = NX_MAX(0, fifo_free_bytes(used_out, fifo_out_len)
source_sz = NX_MAX(source_sz / 2, page_sz);
last_comp_ratio = NX_MAX(NX_MIN(1000UL, last_comp_ratio), 1);