diff --git a/conv/CMakeLists.txt b/conv/CMakeLists.txt
index 333af1f..e7dc96c 100644
--- a/conv/CMakeLists.txt
+++ b/conv/CMakeLists.txt
@@ -24,3 +24,6 @@ target_link_libraries(feat_dcode PRIVATE args)
 # ---- procedural of preprocessing
 add_executable(aprob_bmap common.hh aprob_bmap.cc)
 target_link_libraries(aprob_bmap PRIVATE args)
+
+add_executable(bmap_fmap common.hh bmap_fmap.cc)
+target_link_libraries(bmap_fmap PRIVATE args)
diff --git a/conv/bmap_fmap.cc b/conv/bmap_fmap.cc
new file mode 100644
index 0000000..23c5e27
--- /dev/null
+++ b/conv/bmap_fmap.cc
@@ -0,0 +1,95 @@
+#include <cassert>
+#include <cmath>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <utility>
+
+#include <args.hxx>
+
+#include "common.hh"
+
+
+namespace param {
+using namespace ::args;
+
+ArgumentParser parser {
+  "converter: bmap -> fmap"
+};
+HelpFlag help {
+  parser, "help", "display this menu", {'h', "help"},
+};
+
+ValueFlag<uint32_t> fnum {
+  parser, "64", "number of feature kinds", {"fnum"}, 64,
+};
+
+}  // namespace param
+
+
+static bool NextCombination(auto begin, auto end) noexcept {
+  auto first = std::find(begin, end, true);
+  if (first == end) {
+    return false;
+  }
+  if (!NextCombination(first+1, end)) {
+    if (first+1 >= end || *(first+1)) {
+      return false;
+    }
+    const auto n = std::count(first+2, end, true);
+    std::fill(first+2  , first+2+n, true);
+    std::fill(first+2+n, end      , false);
+    *first     = false;
+    *(first+1) = true;
+  }
+  return true;
+}
+
+static void Exec() {
+  const auto bmap = ReadMatrix<uint32_t>(std::cin);
+  const auto fnum  = args::get(param::fnum);
+
+  for (uint32_t t = 0; t < bmap.size(); ++t) {
+    const auto& blocks = bmap[t];
+    const auto  bnum   = static_cast<uint32_t>(blocks.size());
+    Enforce(fnum < pow(bnum, 2), "number of blocks is too less");
+
+    std::vector<bool> C(bnum);
+    uint32_t r = 0;
+    for (uint32_t f = 0; f < fnum; ++f) {
+      if (!NextCombination(C.begin(), C.end())) {
+        ++r;
+        assert(r <= bnum);
+        std::fill(C.begin(), C.begin()+r, 1);
+        std::fill(C.begin()+r, C.end(), 0);
+      }
+      auto itr = C.begin();
+      for (uint32_t i = 0; i < r; ++i, ++itr) {
+        itr = std::find(itr, C.end(), true);
+        if (itr >= C.end()) {
+          for (const auto& b : C) std::cout << !!b << ',';
+          std::cout << std::endl;
+          assert(false);
+        }
+        const auto idx = std::distance(C.begin(), itr);
+        std::cout << blocks[idx] << ' ';
+      }
+      std::cout << '\n';
+    }
+    std::cout << "----\n";
+  }
+}
+
+int main(int argc, char** argv)
+try {
+  param::parser.ParseCLI(argc, argv);
+  Exec();
+  return EXIT_SUCCESS;
+} catch (const args::Help&) {
+  std::cout << param::parser << std::endl;
+  return EXIT_SUCCESS;
+} catch (const std::exception& e) {
+  std::cerr << e.what() << std::endl;
+  return EXIT_FAILURE;
+}
+