lm3g_templates.c
/* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */
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* This work was supported in part by funding from the Defense Advanced
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/*
* \file lm3g_templates.c Core Sphinx 3-gram code used in
* DMP/DMP32/ARPA (for now) model code.
*/
#include <assert.h>
/* Locate a specific bigram within a bigram list */
#define BINARY_SEARCH_THRESH 16
static int32
find_bg(bigram_t * bg, int32 n, int32 w)
{
int32 i, b, e;
/* Binary search until segment size < threshold */
b = 0;
e = n;
while (e - b > BINARY_SEARCH_THRESH) {
i = (b + e) >> 1;
if (bg[i].wid < w)
b = i + 1;
else if (bg[i].wid > w)
e = i;
else
return i;
}
/* Linear search within narrowed segment */
for (i = b; (i < e) && (bg[i].wid != w); i++);
return ((i < e) ? i : -1);
}
static int32
lm3g_bg_score(NGRAM_MODEL_TYPE *model,
int32 lw1, int32 lw2, int32 *n_used)
{
int32 i, n, b, score;
bigram_t *bg;
if (lw1 < 0 || model->base.n < 2) {
*n_used = 1;
return model->lm3g.unigrams[lw2].prob1.l;
}
b = FIRST_BG(model, lw1);
n = FIRST_BG(model, lw1 + 1) - b;
bg = model->lm3g.bigrams + b;
if ((i = find_bg(bg, n, lw2)) >= 0) {
/* Access mode = bigram */
*n_used = 2;
score = model->lm3g.prob2[bg[i].prob2].l;
}
else {
/* Access mode = unigram */
*n_used = 1;
score = model->lm3g.unigrams[lw1].bo_wt1.l + model->lm3g.unigrams[lw2].prob1.l;
}
return (score);
}
static void
load_tginfo(NGRAM_MODEL_TYPE *model, int32 lw1, int32 lw2)
{
int32 i, n, b, t;
bigram_t *bg;
tginfo_t *tginfo;
/* First allocate space for tg information for bg lw1,lw2 */
tginfo = (tginfo_t *) listelem_malloc(model->lm3g.le);
tginfo->w1 = lw1;
tginfo->tg = NULL;
tginfo->next = model->lm3g.tginfo[lw2];
model->lm3g.tginfo[lw2] = tginfo;
/* Locate bigram lw1,lw2 */
b = model->lm3g.unigrams[lw1].bigrams;
n = model->lm3g.unigrams[lw1 + 1].bigrams - b;
bg = model->lm3g.bigrams + b;
if ((n > 0) && ((i = find_bg(bg, n, lw2)) >= 0)) {
tginfo->bowt = model->lm3g.bo_wt2[bg[i].bo_wt2].l;
/* Find t = Absolute first trigram index for bigram lw1,lw2 */
b += i; /* b = Absolute index of bigram lw1,lw2 on disk */
t = FIRST_TG(model, b);
tginfo->tg = model->lm3g.trigrams + t;
/* Find #tg for bigram w1,w2 */
tginfo->n_tg = FIRST_TG(model, b + 1) - t;
}
else { /* No bigram w1,w2 */
tginfo->bowt = 0;
tginfo->n_tg = 0;
}
}
/* Similar to find_bg */
static int32
find_tg(trigram_t * tg, int32 n, int32 w)
{
int32 i, b, e;
b = 0;
e = n;
while (e - b > BINARY_SEARCH_THRESH) {
i = (b + e) >> 1;
if (tg[i].wid < w)
b = i + 1;
else if (tg[i].wid > w)
e = i;
else
return i;
}
for (i = b; (i < e) && (tg[i].wid != w); i++);
return ((i < e) ? i : -1);
}
static int32
lm3g_tg_score(NGRAM_MODEL_TYPE *model, int32 lw1,
int32 lw2, int32 lw3, int32 *n_used)
{
ngram_model_t *base = &model->base;
int32 i, n, score;
trigram_t *tg;
tginfo_t *tginfo, *prev_tginfo;
if ((base->n < 3) || (lw1 < 0) || (lw2 < 0))
return (lm3g_bg_score(model, lw2, lw3, n_used));
prev_tginfo = NULL;
for (tginfo = model->lm3g.tginfo[lw2]; tginfo; tginfo = tginfo->next) {
if (tginfo->w1 == lw1)
break;
prev_tginfo = tginfo;
}
if (!tginfo) {
load_tginfo(model, lw1, lw2);
tginfo = model->lm3g.tginfo[lw2];
}
else if (prev_tginfo) {
prev_tginfo->next = tginfo->next;
tginfo->next = model->lm3g.tginfo[lw2];
model->lm3g.tginfo[lw2] = tginfo;
}
tginfo->used = 1;
/* Trigrams for w1,w2 now pointed to by tginfo */
n = tginfo->n_tg;
tg = tginfo->tg;
if ((i = find_tg(tg, n, lw3)) >= 0) {
/* Access mode = trigram */
*n_used = 3;
score = model->lm3g.prob3[tg[i].prob3].l;
}
else {
score = tginfo->bowt + lm3g_bg_score(model, lw2, lw3, n_used);
}
return (score);
}
static int32
lm3g_template_score(ngram_model_t *base, int32 wid,
int32 *history, int32 n_hist,
int32 *n_used)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base;
switch (n_hist) {
case 0:
/* Access mode: unigram */
*n_used = 1;
return model->lm3g.unigrams[wid].prob1.l;
case 1:
return lm3g_bg_score(model, history[0], wid, n_used);
case 2:
default:
/* Anything greater than 2 is the same as a trigram for now. */
return lm3g_tg_score(model, history[1], history[0], wid, n_used);
}
}
static int32
lm3g_template_raw_score(ngram_model_t *base, int32 wid,
int32 *history, int32 n_hist,
int32 *n_used)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base;
int32 score;
switch (n_hist) {
case 0:
/* Access mode: unigram */
*n_used = 1;
/* Undo insertion penalty. */
score = model->lm3g.unigrams[wid].prob1.l - base->log_wip;
/* Undo language weight. */
score = (int32)(score / base->lw);
/* Undo unigram interpolation */
if (strcmp(base->word_str[wid], "<s>") != 0) { /* FIXME: configurable start_sym */
score = logmath_log(base->lmath,
logmath_exp(base->lmath, score)
- logmath_exp(base->lmath,
base->log_uniform + base->log_uniform_weight));
}
return score;
case 1:
score = lm3g_bg_score(model, history[0], wid, n_used);
break;
case 2:
default:
/* Anything greater than 2 is the same as a trigram for now. */
score = lm3g_tg_score(model, history[1], history[0], wid, n_used);
break;
}
/* FIXME (maybe): This doesn't undo unigram weighting in backoff cases. */
return (int32)((score - base->log_wip) / base->lw);
}
static int32
lm3g_template_add_ug(ngram_model_t *base,
int32 wid, int32 lweight)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base;
return lm3g_add_ug(base, &model->lm3g, wid, lweight);
}
static void
lm3g_template_flush(ngram_model_t *base)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base;
lm3g_tginfo_reset(base, &model->lm3g);
}
typedef struct lm3g_iter_s {
ngram_iter_t base;
unigram_t *ug;
bigram_t *bg;
trigram_t *tg;
} lm3g_iter_t;
static ngram_iter_t *
lm3g_template_iter(ngram_model_t *base, int32 wid,
int32 *history, int32 n_hist)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base;
lm3g_iter_t *itor = ckd_calloc(1, sizeof(*itor));
ngram_iter_init((ngram_iter_t *)itor, base, n_hist, FALSE);
if (n_hist == 0) {
/* Unigram is the easiest. */
itor->ug = model->lm3g.unigrams + wid;
return (ngram_iter_t *)itor;
}
else if (n_hist == 1) {
int32 i, n, b;
/* Find the bigram, as in bg_score above (duplicate code...) */
itor->ug = model->lm3g.unigrams + history[0];
b = FIRST_BG(model, history[0]);
n = FIRST_BG(model, history[0] + 1) - b;
itor->bg = model->lm3g.bigrams + b;
/* If no such bigram exists then fail. */
if ((i = find_bg(itor->bg, n, wid)) < 0) {
ngram_iter_free((ngram_iter_t *)itor);
return NULL;
}
itor->bg += i;
return (ngram_iter_t *)itor;
}
else if (n_hist == 2) {
int32 i, n;
tginfo_t *tginfo, *prev_tginfo;
/* Find the trigram, as in tg_score above (duplicate code...) */
itor->ug = model->lm3g.unigrams + history[1];
prev_tginfo = NULL;
for (tginfo = model->lm3g.tginfo[history[0]];
tginfo; tginfo = tginfo->next) {
if (tginfo->w1 == history[1])
break;
prev_tginfo = tginfo;
}
if (!tginfo) {
load_tginfo(model, history[1], history[0]);
tginfo = model->lm3g.tginfo[history[0]];
}
else if (prev_tginfo) {
prev_tginfo->next = tginfo->next;
tginfo->next = model->lm3g.tginfo[history[0]];
model->lm3g.tginfo[history[0]] = tginfo;
}
tginfo->used = 1;
/* Trigrams for w1,w2 now pointed to by tginfo */
n = tginfo->n_tg;
itor->tg = tginfo->tg;
if ((i = find_tg(itor->tg, n, wid)) >= 0) {
itor->tg += i;
/* Now advance the bigram pointer accordingly. FIXME:
* Note that we actually already found the relevant bigram
* in load_tginfo. */
itor->bg = model->lm3g.bigrams;
while (FIRST_TG(model, (itor->bg - model->lm3g.bigrams + 1))
<= (itor->tg - model->lm3g.trigrams))
++itor->bg;
return (ngram_iter_t *)itor;
}
else {
ngram_iter_free((ngram_iter_t *)itor);
return (ngram_iter_t *)NULL;
}
}
else {
/* Should not happen. */
assert(n_hist == 0); /* Guaranteed to fail. */
ngram_iter_free((ngram_iter_t *)itor);
return NULL;
}
}
static ngram_iter_t *
lm3g_template_mgrams(ngram_model_t *base, int m)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base;
lm3g_iter_t *itor = ckd_calloc(1, sizeof(*itor));
ngram_iter_init((ngram_iter_t *)itor, base, m, FALSE);
itor->ug = model->lm3g.unigrams;
itor->bg = model->lm3g.bigrams;
itor->tg = model->lm3g.trigrams;
/* Advance bigram pointer to match first trigram. */
if (m > 1 && base->n_counts[1] > 1) {
while (FIRST_TG(model, (itor->bg - model->lm3g.bigrams + 1))
<= (itor->tg - model->lm3g.trigrams))
++itor->bg;
}
/* Advance unigram pointer to match first bigram. */
if (m > 0 && base->n_counts[0] > 1) {
while (itor->ug[1].bigrams <= (itor->bg - model->lm3g.bigrams))
++itor->ug;
}
return (ngram_iter_t *)itor;
}
static ngram_iter_t *
lm3g_template_successors(ngram_iter_t *bitor)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)bitor->model;
lm3g_iter_t *from = (lm3g_iter_t *)bitor;
lm3g_iter_t *itor = ckd_calloc(1, sizeof(*itor));
itor->ug = from->ug;
switch (bitor->m) {
case 0:
/* Next itor bigrams is the same as this itor bigram or
itor bigrams is more than total count. This means no successors */
if (((itor->ug + 1) - model->lm3g.unigrams < bitor->model->n_counts[0] &&
itor->ug->bigrams == (itor->ug + 1)->bigrams) ||
itor->ug->bigrams == bitor->model->n_counts[1])
goto done;
/* Start iterating from first bigram successor of from->ug. */
itor->bg = model->lm3g.bigrams + itor->ug->bigrams;
break;
case 1:
itor->bg = from->bg;
/* This indicates no successors */
if (((itor->bg + 1) - model->lm3g.bigrams < bitor->model->n_counts[1] &&
FIRST_TG (model, itor->bg - model->lm3g.bigrams) ==
FIRST_TG (model, (itor->bg + 1) - model->lm3g.bigrams)) ||
FIRST_TG (model, itor->bg - model->lm3g.bigrams) == bitor->model->n_counts[2])
goto done;
/* Start iterating from first trigram successor of from->bg. */
itor->tg = (model->lm3g.trigrams
+ FIRST_TG(model, (itor->bg - model->lm3g.bigrams)));
#if 0
printf("%s %s => %d (%s)\n",
model->base.word_str[itor->ug - model->lm3g.unigrams],
model->base.word_str[itor->bg->wid],
FIRST_TG(model, (itor->bg - model->lm3g.bigrams)),
model->base.word_str[itor->tg->wid]);
#endif
break;
case 2:
default:
/* All invalid! */
goto done;
}
ngram_iter_init((ngram_iter_t *)itor, bitor->model, bitor->m + 1, TRUE);
return (ngram_iter_t *)itor;
done:
ckd_free(itor);
return NULL;
}
static int32 const *
lm3g_template_iter_get(ngram_iter_t *base,
int32 *out_score, int32 *out_bowt)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base->model;
lm3g_iter_t *itor = (lm3g_iter_t *)base;
base->wids[0] = itor->ug - model->lm3g.unigrams;
if (itor->bg) base->wids[1] = itor->bg->wid;
if (itor->tg) base->wids[2] = itor->tg->wid;
#if 0
printf("itor_get: %d %d %d\n", base->wids[0], base->wids[1], base->wids[2]);
#endif
switch (base->m) {
case 0:
*out_score = itor->ug->prob1.l;
*out_bowt = itor->ug->bo_wt1.l;
break;
case 1:
*out_score = model->lm3g.prob2[itor->bg->prob2].l;
if (model->lm3g.bo_wt2)
*out_bowt = model->lm3g.bo_wt2[itor->bg->bo_wt2].l;
else
*out_bowt = 0;
break;
case 2:
*out_score = model->lm3g.prob3[itor->tg->prob3].l;
*out_bowt = 0;
break;
default: /* Should not happen. */
return NULL;
}
return base->wids;
}
static ngram_iter_t *
lm3g_template_iter_next(ngram_iter_t *base)
{
NGRAM_MODEL_TYPE *model = (NGRAM_MODEL_TYPE *)base->model;
lm3g_iter_t *itor = (lm3g_iter_t *)base;
switch (base->m) {
case 0:
++itor->ug;
/* Check for end condition. */
if (itor->ug - model->lm3g.unigrams >= base->model->n_counts[0])
goto done;
break;
case 1:
++itor->bg;
/* Check for end condition. */
if (itor->bg - model->lm3g.bigrams >= base->model->n_counts[1])
goto done;
/* Advance unigram pointer if necessary in order to get one
* that points to this bigram. */
while (itor->bg - model->lm3g.bigrams >= itor->ug[1].bigrams) {
/* Stop if this is a successor iterator, since we don't
* want a new unigram. */
if (base->successor)
goto done;
++itor->ug;
if (itor->ug == model->lm3g.unigrams + base->model->n_counts[0]) {
E_ERROR("Bigram %d has no valid unigram parent\n",
itor->bg - model->lm3g.bigrams);
goto done;
}
}
break;
case 2:
++itor->tg;
/* Check for end condition. */
if (itor->tg - model->lm3g.trigrams >= base->model->n_counts[2])
goto done;
/* Advance bigram pointer if necessary. */
while (itor->tg - model->lm3g.trigrams >=
FIRST_TG(model, (itor->bg - model->lm3g.bigrams + 1))) {
if (base->successor)
goto done;
++itor->bg;
if (itor->bg == model->lm3g.bigrams + base->model->n_counts[1]) {
E_ERROR("Trigram %d has no valid bigram parent\n",
itor->tg - model->lm3g.trigrams);
goto done;
}
}
/* Advance unigram pointer if necessary. */
while (itor->bg - model->lm3g.bigrams >= itor->ug[1].bigrams) {
++itor->ug;
if (itor->ug == model->lm3g.unigrams + base->model->n_counts[0]) {
E_ERROR("Trigram %d has no valid unigram parent\n",
itor->tg - model->lm3g.trigrams);
goto done;
}
}
break;
default: /* Should not happen. */
goto done;
}
return (ngram_iter_t *)itor;
done:
ngram_iter_free(base);
return NULL;
}
static void
lm3g_template_iter_free(ngram_iter_t *base)
{
ckd_free(base);
}
unigram_s::bo_wt1
lmprob_t bo_wt1
Unigram backoff weight.
Definition: lm3g_model.h:93
ngram_model_s::log_uniform
int32 log_uniform
Log of uniform (0-gram) probability.
Definition: ngram_model_internal.h:70
tginfo_s::w1
int32 w1
lw1 component of bigram lw1,lw2.
Definition: lm3g_model.h:130
ckd_calloc
#define ckd_calloc(n, sz)
Macros to simplify the use of above functions.
Definition: ckd_alloc.h:248
ngram_model_s::word_str
char ** word_str
Unigram names.
Definition: ngram_model_internal.h:73
ngram_iter_free
SPHINXBASE_EXPORT void ngram_iter_free(ngram_iter_t *itor)
Terminate an M-gram iterator.
Definition: ngram_model.c:764
listelem_malloc
#define listelem_malloc(le)
Allocate a list element and return pointer to it.
Definition: listelem_alloc.h:86
ngram_model_s::log_uniform_weight
int32 log_uniform_weight
Log of uniform weight (i.e.
Definition: ngram_model_internal.h:71
bigram_s
Bigram structure.
Definition: ngram_model_arpa.h:52
ngram_iter_s::m
int16 m
Order of history.
Definition: ngram_model_internal.h:196
logmath_log
SPHINXBASE_EXPORT int logmath_log(logmath_t *lmath, float64 p)
Convert linear floating point number to integer log in base B.
Definition: logmath.c:447
ngram_model_s::n_counts
int32 * n_counts
Counts for 1, 2, 3, ...
Definition: ngram_model_internal.h:57
tginfo_s::used
int32 used
whether used since last lm_reset
Definition: lm3g_model.h:134
trigram_s::prob3
uint16 prob3
Index into array of actual trigram probs.
Definition: ngram_model_arpa.h:68
ckd_free
SPHINXBASE_EXPORT void ckd_free(void *ptr)
Test and free a 1-D array.
Definition: ckd_alloc.c:241
lm3g_iter_s
Definition: lm3g_templates.c:276
unigram_s
Unigram structure (common among all lm3g implementations)
Definition: lm3g_model.h:91
unigram_s::bigrams
int32 bigrams
Index of 1st entry in lm_t.bigrams[].
Definition: lm3g_model.h:94
tginfo_s::tg
trigram_t * tg
Trigrams for lw1,lw2.
Definition: lm3g_model.h:135
tginfo_s
Trigram information cache.
Definition: lm3g_model.h:129
trigram_s
Trigram structure.
Definition: ngram_model_arpa.h:66
tginfo_s::n_tg
int32 n_tg
number tg for parent bigram lw1,lw2
Definition: lm3g_model.h:132
ngram_model_s::n
uint8 n
This is an n-gram model (1, 2, 3, ...).
Definition: ngram_model_internal.h:61
bigram_s::prob2
uint16 prob2
Index into array of actual bigram probs.
Definition: ngram_model_arpa.h:54
ngram_model_s::lmath
logmath_t * lmath
Log-math object.
Definition: ngram_model_internal.h:66
bigram_s::bo_wt2
uint16 bo_wt2
Index into array of actual bigram backoff wts.
Definition: ngram_model_arpa.h:55
tginfo_s::next
struct tginfo_s * next
Next lw1 with same parent lw2; NULL if none.
Definition: lm3g_model.h:136
unigram_s::prob1
lmprob_t prob1
Unigram probability.
Definition: lm3g_model.h:92
E_ERROR
#define E_ERROR
Print error message to standard error stream.
Definition: err.h:169
ngram_model_s::lw
float32 lw
Language model scaling factor.
Definition: ngram_model_internal.h:67
ngram_iter_s
Base iterator structure for N-grams.
Definition: ngram_model_internal.h:193
ngram_iter_s::wids
int32 * wids
Scratch space for word IDs.
Definition: ngram_model_internal.h:195
ngram_model_s
Common implementation of ngram_model_t.
Definition: ngram_model_internal.h:55
tginfo_s::bowt
int32 bowt
tg bowt for lw1,lw2
Definition: lm3g_model.h:133
logmath_exp
SPHINXBASE_EXPORT float64 logmath_exp(logmath_t *lmath, int logb_p)
Convert integer log in base B to linear floating point.
Definition: logmath.c:456
bigram_s::wid
uint32 wid
Index of unigram entry for this.
Definition: ngram_model_arpa.h:53
ngram_iter_s::successor
int16 successor
Is this a successor iterator?
Definition: ngram_model_internal.h:197
ngram_model_s::log_wip
int32 log_wip
Log of word insertion penalty.
Definition: ngram_model_internal.h:68
trigram_s::wid
uint32 wid
Index of unigram entry for this.
Definition: ngram_model_arpa.h:67