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Diffstat (limited to 'media/sphinxbase/src/libsphinxbase/lm/lm3g_model.h')
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diff --git a/media/sphinxbase/src/libsphinxbase/lm/lm3g_model.h b/media/sphinxbase/src/libsphinxbase/lm/lm3g_model.h new file mode 100644 index 000000000..698ed81f5 --- /dev/null +++ b/media/sphinxbase/src/libsphinxbase/lm/lm3g_model.h @@ -0,0 +1,177 @@ +/* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */ +/* ==================================================================== + * Copyright (c) 1999-2007 Carnegie Mellon University. All rights + * reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * This work was supported in part by funding from the Defense Advanced + * Research Projects Agency and the National Science Foundation of the + * United States of America, and the CMU Sphinx Speech Consortium. + * + * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND + * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY + * NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * ==================================================================== + * + */ +/* + * \file lm3g_model.h Core Sphinx 3-gram code used in + * DMP/DMP32/ARPA (for now) model code. + * + * Author: A cast of thousands, probably. + */ + +#ifndef __NGRAM_MODEL_LM3G_H__ +#define __NGRAM_MODEL_LM3G_H__ + +#include "sphinxbase/listelem_alloc.h" + +#include "ngram_model_internal.h" + +/** + * Type used to store language model probabilities + */ +typedef union { + float32 f; + int32 l; +} lmprob_t; + +/** + * Bigram probs and bo-wts, and trigram probs are kept in separate + * tables rather than within the bigram_t and trigram_t structures. + * These tables hold unique prob and bo-wt values. The following tree + * structure is used to construct these tables of unique values. + * Whenever a new value is read from the LM file, the sorted tree + * structure is searched to see if the value already exists, and + * inserted if not found. + */ +typedef struct sorted_entry_s { + lmprob_t val; /**< value being kept in this node */ + uint32 lower; /**< index of another entry. All descendants down + this path have their val < this node's val. + 0 => no son exists (0 is root index) */ + uint32 higher; /**< index of another entry. All descendants down + this path have their val > this node's val + 0 => no son exists (0 is root index) */ +} sorted_entry_t; + +/** + * The sorted list. list is a (64K long) array. The first entry is the + * root of the tree and is created during initialization. + */ +typedef struct { + sorted_entry_t *list; + int32 free; /**< first free element in list */ + int32 size; +} sorted_list_t; + +/** + * Unigram structure (common among all lm3g implementations) + */ +typedef struct unigram_s { + lmprob_t prob1; /**< Unigram probability. */ + lmprob_t bo_wt1; /**< Unigram backoff weight. */ + int32 bigrams; /**< Index of 1st entry in lm_t.bigrams[] */ +} unigram_t; + +/** + * Bigram structure (might be implemented differently) + */ +typedef struct bigram_s bigram_t; +/** + * Trigram structure (might be implemented differently) + */ +typedef struct trigram_s trigram_t; + + +/* + * To conserve space, bigram info is kept in many tables. Since the number + * of distinct values << #bigrams, these table indices can be 16-bit values. + * prob2 and bo_wt2 are such indices, but keeping trigram index is less easy. + * It is supposed to be the index of the first trigram entry for each bigram. + * But such an index cannot be represented in 16-bits, hence the following + * segmentation scheme: Partition bigrams into segments of BG_SEG_SZ + * consecutive entries, such that #trigrams in each segment <= 2**16 (the + * corresponding trigram segment). The bigram_t.trigrams value is then a + * 16-bit relative index within the trigram segment. A separate table-- + * lm_t.tseg_base--has the index of the 1st trigram for each bigram segment. + */ +#define BG_SEG_SZ 512 /* chosen so that #trigram/segment <= 2**16 */ +#define LOG_BG_SEG_SZ 9 + +/** + * Trigram information cache. + * + * The following trigram information cache eliminates most traversals of 1g->2g->3g + * tree to locate trigrams for a given bigram (lw1,lw2). The organization is optimized + * for locality of access (to the same lw1), given lw2. + */ +typedef struct tginfo_s { + int32 w1; /**< lw1 component of bigram lw1,lw2. All bigrams with + same lw2 linked together (see lm_t.tginfo). */ + int32 n_tg; /**< number tg for parent bigram lw1,lw2 */ + int32 bowt; /**< tg bowt for lw1,lw2 */ + int32 used; /**< whether used since last lm_reset */ + trigram_t *tg; /**< Trigrams for lw1,lw2 */ + struct tginfo_s *next; /**< Next lw1 with same parent lw2; NULL if none. */ +} tginfo_t; + +/** + * Common internal structure for Sphinx 3-gram models. + */ +typedef struct lm3g_model_s { + unigram_t *unigrams; + bigram_t *bigrams; + trigram_t *trigrams; + lmprob_t *prob2; /**< Table of actual bigram probs */ + int32 n_prob2; /**< prob2 size */ + lmprob_t *bo_wt2; /**< Table of actual bigram backoff weights */ + int32 n_bo_wt2; /**< bo_wt2 size */ + lmprob_t *prob3; /**< Table of actual trigram probs */ + int32 n_prob3; /**< prob3 size */ + int32 *tseg_base; /**< tseg_base[i>>LOG_BG_SEG_SZ] = index of 1st + trigram for bigram segment (i>>LOG_BG_SEG_SZ) */ + tginfo_t **tginfo; /**< tginfo[lw2] is head of linked list of trigram information for + some cached subset of bigrams (*,lw2). */ + listelem_alloc_t *le; /**< List element allocator for tginfo. */ +} lm3g_model_t; + +void lm3g_tginfo_free(ngram_model_t *base, lm3g_model_t *lm3g); +void lm3g_tginfo_reset(ngram_model_t *base, lm3g_model_t *lm3g); +void lm3g_apply_weights(ngram_model_t *base, + lm3g_model_t *lm3g, + float32 lw, float32 wip, float32 uw); +int32 lm3g_add_ug(ngram_model_t *base, + lm3g_model_t *lm3g, int32 wid, int32 lweight); + + +/** + * Initialize sorted list with the 0-th entry = MIN_PROB_F, which may be needed + * to replace spurious values in the Darpa LM file. + */ +void init_sorted_list(sorted_list_t *l); +void free_sorted_list(sorted_list_t *l); +lmprob_t *vals_in_sorted_list(sorted_list_t *l); +int32 sorted_id(sorted_list_t * l, int32 *val); + +#endif /* __NGRAM_MODEL_LM3G_H__ */ |