1 files changed, 46 insertions, 0 deletions
diff --git a/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h
new file mode 100644
index 0000000..d4a9a5a
--- /dev/null
+++ b/kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h
@@ -0,0 +1,46 @@
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright 2005-2010 Google, Inc.
+// Author: sorenj@google.com (Jeffrey Sorensen)
+//         dr@google.com (Doug Rohde)
+
+#ifndef FST_EXTENSIONS_NGRAM_NTHBIT_H_
+#define FST_EXTENSIONS_NGRAM_NTHBIT_H_
+
+#include <fst/types.h>
+
+extern uint32 nth_bit_bit_offset[];
+
+inline uint32 nth_bit(uint64 v, uint32 r) {
+  uint32 shift = 0;
+  uint32 c = __builtin_popcount(v & 0xffffffff);
+  uint32 mask = -(r > c);
+  r -= c & mask;
+  shift += (32 & mask);
+
+  c = __builtin_popcount((v >> shift) & 0xffff);
+  mask = -(r > c);
+  r -= c & mask;
+  shift += (16 & mask);
+
+  c = __builtin_popcount((v >> shift) & 0xff);
+  mask = -(r > c);
+  r -= c & mask;
+  shift += (8 & mask);
+
+  return shift + ((nth_bit_bit_offset[(v >> shift) & 0xff] >>
+                   ((r - 1) << 2)) & 0xf);
+}
+
+#endif  // FST_EXTENSIONS_NGRAM_NTHBIT_H_