* src/misc/minato.cc, src/misc/minato.hh: New files.

* src/misc/Makefile.am (misc_HEADERS, libmisc_la_SOURCES): Add them.
* src/tgbaalgos/ltl2tgba_fm.cc (ltl_to_tgba_fm): Use minato_isop.

src/misc/minato.cc

@@ -0,0 +1,109 @@
+#include "minato.hh"
+#include <utility>
+
+namespace spot
+{
+
+  minato_isop::minato_isop(bdd input)
+    : ret(bddfalse)
+  {
+    todo.push(local_vars(input, input));
+    cube.push(bddtrue);
+  }
+
+  bdd
+  minato_isop::next()
+  {
+    while (todo.size())
+      {
+	local_vars& l = todo.top();
+	switch (l.step)
+	  {
+	  case local_vars::FirstStep:
+	    if (l.f_min == bddfalse)
+	      {
+		ret = bddfalse;
+		todo.pop();
+		continue;
+	      }
+	    if (l.f_max == bddtrue)
+	      {
+		ret = bddtrue;
+		todo.pop();
+		return cube.top();
+	      }
+	    l.step = local_vars::SecondStep;
+
+	    {
+	      // Pick the topmost variable.
+	      int v_min = bdd_var(l.f_min);
+	      int v_max = bdd_var(l.f_max);
+	      int v = std::min(v_min, v_max);
+
+	      // The following two `if's do
+	      //   v0 = bdd_nithvar(v);
+	      //   v1 = bdd_ithvar(v);
+	      //   f0_min = bdd_restrict(f_min, v0);
+	      //   f0_max = bdd_restrict(f_max, v0);
+	      //   f1_min = bdd_restrict(f_min, v1);
+	      //   f1_max = bdd_restrict(f_max, v1);
+	      // but since we now the v is the topmost variable,
+	      // its more efficient to use bdd_low and bdd_high.
+	      if (v == v_min)
+		{
+		  l.f0_min = bdd_low(l.f_min);
+		  l.f1_min = bdd_high(l.f_min);
+		}
+	      else
+		{
+		  l.f1_min = l.f0_min = l.f_min;
+		}
+	      if (v == v_max)
+		{
+		  l.f0_max = bdd_low(l.f_max);
+		  l.f1_max = bdd_high(l.f_max);
+		}
+	      else
+		{
+		  l.f1_max = l.f0_max = l.f_max;
+		}
+
+	      l.v1 = bdd_ithvar(v);
+	      cube.push(cube.top() & bdd_nithvar(v));
+	      todo.push(local_vars(l.f0_min - l.f1_max, l.f0_max));
+	    }
+	    continue;
+
+	  case local_vars::SecondStep:
+	    l.step = local_vars::ThirdStep;
+	    l.g0 = ret;
+	    cube.pop();
+	    cube.push(cube.top() & l.v1);
+	    todo.push(local_vars(l.f1_min - l.f0_max, l.f1_max));
+	    continue;
+
+	  case local_vars::ThirdStep:
+	    l.step = local_vars::FourthStep;
+	    l.g1 = ret;
+	    cube.pop();
+	    {
+	      bdd f0s_min = l.f0_min - l.g0;
+	      bdd f1s_min = l.f1_min - l.g1;
+	      bdd fs_max = l.f0_max & l.f1_max;
+	      bdd fs_min = fs_max & (f0s_min | f1s_min);
+	      todo.push(local_vars(fs_min, fs_max));
+	    }
+	    continue;
+
+	  case local_vars::FourthStep:
+	    ret |= (l.g0 - l.v1) | (l.g1 & l.v1);
+	    todo.pop();
+	    continue;
+	  }
+	// Unreachable code.
+	assert(0);
+      }
+    return bddfalse;
+  }
+
+}