optimize `num_ids_word` init logic;

init `max_prio` by initialization-list

riscv/plic.cc

@@ -67,15 +67,12 @@
 #define REG_SIZE                0x1000000
 
 plic_t::plic_t(std::vector<processor_t*>& procs, bool smode, uint32_t ndev)
-  : procs(procs), contexts(procs.size() * (smode ? 2 : 1))
+  : procs(procs), contexts(procs.size() * (smode ? 2 : 1)),
+  num_ids(ndev + 1), num_ids_word(((ndev + 1) + (32 - 1)) / 32),
+  max_prio((1UL << PLIC_PRIO_BITS) - 1) 
 {
   size_t contexts_per_hart = smode ? 2 : 1;
 
-  num_ids = ndev + 1;
-  num_ids_word = num_ids / 32;
-  if ((num_ids_word * 32) < num_ids)
-    num_ids_word++;
-  max_prio = (1UL << PLIC_PRIO_BITS) - 1;
   memset(priority, 0, sizeof(priority));
   memset(level, 0, sizeof(level));