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Diffstat (limited to 'kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h')
-rw-r--r-- | kaldi_io/src/tools/openfst/include/fst/extensions/ngram/nthbit.h | 46 |
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: [email protected] (Jeffrey Sorensen) +// [email protected] (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_ |