src/libpocketsphinx/ngram_search.c File Reference

N-Gram based multi-pass search ("FBS"). More...

#include <string.h>
#include <assert.h>
#include <ckd_alloc.h>
#include <listelem_alloc.h>
#include <err.h>
#include "pocketsphinx_internal.h"
#include "ps_lattice_internal.h"
#include "ngram_search.h"
#include "ngram_search_fwdtree.h"
#include "ngram_search_fwdflat.h"

Go to the source code of this file.

Functions
ps_search_t *	ngram_search_init (cmd_ln_t *config, acmod_t *acmod, s3dict_t *dict, dict2pid_t *d2p)
	Initialize the N-Gram search module.
void	ngram_search_free (ps_search_t *search)
	Finalize the N-Gram search module.
int	ngram_search_mark_bptable (ngram_search_t *ngs, int frame_idx)
	Record the current frame's index in the backpointer table.
void	ngram_search_save_bp (ngram_search_t *ngs, int frame_idx, int32 w, int32 score, int32 path, int32 rc)
	Enter a word in the backpointer table.
int	ngram_search_find_exit (ngram_search_t *ngs, int frame_idx, int32 *out_best_score)
	Find the best word exit for the current frame in the backpointer table.
char const *	ngram_search_bp_hyp (ngram_search_t *ngs, int bpidx)
	Backtrace from a given backpointer index to obtain a word hypothesis.
void	ngram_search_alloc_all_rc (ngram_search_t *ngs, int32 w)
	Allocate last phone channels for all possible right contexts for word w.
void	ngram_search_free_all_rc (ngram_search_t *ngs, int32 w)
	Allocate last phone channels for all possible right contexts for word w.
int32	ngram_search_exit_score (ngram_search_t *ngs, bptbl_t *pbe, int rcphone)
	Get the exit score for a backpointer entry with a given right context.
void	ngram_compute_seg_score (ngram_search_t *ngs, bptbl_t *be, float32 lwf, int32 *out_ascr, int32 *out_lscr)
ps_lattice_t *	ngram_search_lattice (ps_search_t *search)
	Construct a word lattice from the current hypothesis.

---

Detailed Description

N-Gram based multi-pass search ("FBS").

Definition in file ngram_search.c.

---

Function Documentation

char const* ngram_search_bp_hyp	(	ngram_search_t *	ngs,
		int	bpidx
	)

Backtrace from a given backpointer index to obtain a word hypothesis.

Returns:

a read-only string with the best hypothesis.

Definition at line 467 of file ngram_search.c.

References bptbl_s::bp, ngram_search_s::bp_table, ps_search_s::hyp_str, NO_BP, ps_search_base, ps_search_dict, and bptbl_s::wid.

int ngram_search_find_exit	(	ngram_search_t *	ngs,
		int	frame_idx,
		int32 *	out_best_score
	)

Find the best word exit for the current frame in the backpointer table.

Returns:

the backpointer index of the best word exit.

Definition at line 425 of file ngram_search.c.

References BETTER_THAN, ngram_search_s::bp_table, ngram_search_s::bp_table_idx, ngram_search_s::n_frame, NO_BP, ps_search_finish_wid, bptbl_s::score, bptbl_s::wid, and WORST_SCORE.

int ngram_search_mark_bptable	(	ngram_search_t *	ngs,
		int	frame_idx
	)

Record the current frame's index in the backpointer table.

Returns:

the current backpointer index.

Definition at line 305 of file ngram_search.c.

References ngram_search_s::bp_table_idx, ngram_search_s::bpidx, ngram_search_s::frm_wordlist, and ngram_search_s::n_frame_alloc.

Referenced by ngram_fwdflat_finish(), ngram_fwdflat_search(), ngram_fwdtree_finish(), and ngram_fwdtree_search().

---