From 8e8f77756db0c70668fe29ce48c65c71d7b0a439 Mon Sep 17 00:00:00 2001
From: Alexandre Duret-Lutz <adl@lrde.epita.fr>
Date: Sun, 17 Jan 2021 16:09:14 +0100
Subject: [PATCH] gen, bitset: use clz() to simplify

Fixes #448.

* spot/gen/automata.cc (ulog2): Here.
* spot/misc/bitset.hh: And there.
---
 spot/gen/automata.cc | 17 ++++-------------
 spot/misc/bitset.hh  | 15 +++------------
 2 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/spot/gen/automata.cc b/spot/gen/automata.cc
index 00b7a5268..165ab8c98 100644
--- a/spot/gen/automata.cc
+++ b/spot/gen/automata.cc
@@ -1,6 +1,6 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2017-2019 Laboratoire de Recherche et Developpement
-// de l'EPITA (LRDE).
+// Copyright (C) 2017-2019, 2021 Laboratoire de Recherche et
+// Developpement de l'EPITA (LRDE).
 //
 // This file is part of Spot, a model checking library.
 //
@@ -21,6 +21,7 @@
 #include <spot/twa/twagraph.hh>
 #include <spot/gen/automata.hh>
 #include <spot/tl/parse.hh>
+#include <spot/misc/clz.hh>
 
 namespace spot
 {
@@ -177,17 +178,7 @@ namespace spot
     {
       assert(n>0);
       --n;
-#ifdef __GNUC__
-      return 8*sizeof(unsigned) - __builtin_clz(n);
-#else
-      unsigned res = 0;
-      while (n)
-        {
-          ++res;
-          n >>= 1;
-        }
-      return res;
-#endif
+      return CHAR_BIT*sizeof(unsigned) - clz(n);
     }
 
     static twa_graph_ptr
diff --git a/spot/misc/bitset.hh b/spot/misc/bitset.hh
index 0ab26763a..f66c6007d 100644
--- a/spot/misc/bitset.hh
+++ b/spot/misc/bitset.hh
@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2018 Laboratoire de Recherche et Développement
+// Copyright (C) 2018, 2021 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -359,19 +359,10 @@ namespace spot
           auto v = data[i];
           if (v == 0)
             {
-              res -= 8*sizeof(word_t);
+              res -= CHAR_BIT*sizeof(word_t);
               continue;
             }
-#ifdef __GNUC__
-          res += 8*sizeof(word_t) - clz(v);
-#else
-          while (v)
-            {
-              ++res;
-              v >>= 1;
-            }
-#endif
-          return res-1;
+          return res + CHAR_BIT*sizeof(word_t) - clz(v) - 1;
         }
       return 0;
     }