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));
sbmtx_lock(model->lm3g.tginfo_mtx);
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 */
if (n_used) *n_used = 3;
score = model->lm3g.prob3[tg[i].prob3].l;
}
else {
score = tginfo->bowt + lm3g_bg_score(model, lw2, lw3, n_used);
}
sbmtx_unlock(model->lm3g.tginfo_mtx);
return (score);
}
int32 lm_bg_score (int32 w1, int32 w2)
{
int32 cscr, tscr, remwt;
lm_t *lm3g;
if (! clm)
return (lm3g_bg_score (w1, w2));
lm3g = lm_get_current ();
/* Get cache LM score and apply language weight */
cscr = cache_lm_score (clm, w1, w2, &remwt);
cscr *= lm3g->lw;
/* Get static trigram LM score, apply remaining weight */
tscr = lm3g_bg_score (w1, w2);
tscr += remwt * lm3g->lw;
/* Return MAX of static trigram LM and dynamic cache LM scores (approx to sum) */
return (cscr > tscr) ? cscr : tscr;
}
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 */
/* This operation is numerically unstable, so try to avoid it
* as possible */
if (base->log_uniform + base->log_uniform_weight > logmath_get_zero(base->lmath)) {
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);
}
