* 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.

ChangeLog

+2003-11-21  Alexandre Duret-Lutz  <adl@src.lip6.fr>
+
+	* 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.
+
 2003-11-14  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
 	* src/ltltest/Makefile.am (AM_CXXFLAGS): New variable.

src/misc/Makefile.am

@@ -7,9 +7,11 @@ misc_HEADERS = \
   bddalloc.hh \
   bddlt.hh \
   hash.hh \
+  minato.hh \
   version.hh
 
 noinst_LTLIBRARIES = libmisc.la
 libmisc_la_SOURCES = \
   bddalloc.cc \
+  minato.cc \
   version.cc

src/misc/minato.cc

+#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;
+  }
+
+}

src/misc/minato.hh

+#ifndef SPOT_MISC_MINATO_HH
+# define SPOT_MISC_MINATO_HH
+
+# include <bdd.h>
+# include <stack>
+
+namespace spot
+{
+  /// \brief Generate an irredundant sum-of-products (ISOP) form of a
+  /// BDD function.
+  ///
+  /// This algorithm implements a derecursived version the Minato-Morreale
+  /// algorithm presented in the following paper.
+  /// \verbatim
+  /// @InProceedings{   minato.92.sasimi,
+  ///   author        = {Shin-ichi Minato},
+  ///   title         = {Fast Generation of Irredundant Sum-of-Products Forms
+  ///                   from Binary Decision Diagrams},
+  ///   booktitle     = {Proceedings of the third Synthesis and Simulation
+  ///                   and Meeting International Interchange workshop
+  ///                   (SASIMI'92)},
+  ///   pages         = {64--73},
+  ///   year          = {1992},
+  ///   address       = {Kobe, Japan},
+  ///   month         = {April}
+  /// }
+  /// \endverbatim
+  class minato_isop
+  {
+  public:
+    /// \brief Conctructor.
+    /// \arg input The BDD function to translate in ISOP.
+    minato_isop(bdd input);
+    /// \brief Compute the next sum term of the ISOP form.
+    /// Return \c bddfalse when all terms have been output.
+    bdd next();
+
+  private:
+    /// Internal variables for minato_isop.
+    struct local_vars
+    {
+      // If you are following the paper, f_min and f_max corresponds
+      // to the pair of BDD function used to encode the ternary function `f'
+      // (see Section 3.4).
+      // Also note that f0, f0', and f0'' all share the same _max function.
+      // Likewise for f1, f1', and f1''.
+      bdd f_min, f_max;
+      // Because we need a non-recursive version of the algorithm,
+      // we had to split it in four step (each step is separated
+      // from the other by a call to ISOP in the original algorithm).
+      enum { FirstStep, SecondStep, ThirdStep, FourthStep } step;
+      bdd v1;
+      bdd f0_min, f0_max;
+      bdd f1_min, f1_max;
+      bdd g0, g1;
+      local_vars(bdd f_min, bdd f_max)
+	: f_min(f_min), f_max(f_max), step(FirstStep) {}
+    };
+    std::stack<local_vars> todo;
+    std::stack<bdd> cube;
+    bdd ret;
+  };
+}
+
+#endif // SPOT_MISC_MINATO_HH

src/tgbaalgos/ltl2tgba_fm.cc

 #include "misc/hash.hh"
 #include "misc/bddalloc.hh"
+#include "misc/minato.hh"
 #include "ltlast/visitor.hh"
 #include "ltlast/allnodes.hh"
 #include "ltlvisit/lunabbrev.hh"
@@ -440,15 +441,10 @@ namespace spot
 
 	std::string now = to_string(f);
 
-	bdd all = res;
-	bdd outside = !all;
-	while (all != bddfalse)
+	minato_isop isop(res);
+	bdd cube;
+	while ((cube = isop.next()) != bddfalse)
 	  {
-
-	    bdd cube = bdd_satone(all);
-	    cube = bdd_simplify(cube, cube | outside);
-	    all -= cube;
-
 	    ltl::formula* dest =
 	      d.conj_bdd_to_formula(bdd_existcomp(cube, d.next_set));
 
@@ -459,7 +455,6 @@ namespace spot
 	    d.conj_bdd_to_atomic_props(a, bdd_existcomp(cube, d.var_set), t);
 	    d.conj_bdd_to_acc(a, bdd_existcomp(cube, d.a_set), t);
 
-
 	    if (formulae_seen.find(dest) == formulae_seen.end())
 	      {
 		formulae_seen.insert(dest);