void vithist_rescore (vithist_t *vh, kbcore_t *kbc,
s3wid_t wid, int32 ef, int32 score, int32 pred, int32 type)
{
vithist_entry_t *pve, tve;
s3lmwid_t lwid;
int32 se, fe;
int32 i;
assert (vh->n_frm == ef);
pve = vh->entry[VITHIST_ID2BLK(pred)] + VITHIST_ID2BLKOFFSET(pred);
/* Create a temporary entry with all the info currently available */
tve.wid = wid;
tve.sf = pve->ef + 1;
tve.ef = ef;
tve.type = type;
tve.valid = 1;
tve.ascr = score - pve->score;
if (pred == 0) { /* Special case for the initial <s> entry */
se = 0;
fe = 1;
} else {
se = vh->frame_start[pve->ef];
fe = vh->frame_start[pve->ef + 1];
}
if (dict_filler_word (kbcore_dict(kbc), wid)) {
tve.lscr = fillpen (kbcore_fillpen(kbc), wid);
tve.score = score + tve.lscr;
tve.pred = pred;
tve.lmstate.lm3g = pve->lmstate.lm3g;
vithist_enter (vh, kbc, &tve);
} else {
lwid = kbcore_dict2lmwid (kbc, wid);
tve.lmstate.lm3g.lwid[0] = lwid;
for (i = se; i < fe; i++) {
pve = vh->entry[VITHIST_ID2BLK(i)] + VITHIST_ID2BLKOFFSET(i);
if (pve->valid) {
tve.lscr = lm_tg_score (kbcore_lm(kbc),
pve->lmstate.lm3g.lwid[1],
pve->lmstate.lm3g.lwid[0],
lwid);
tve.score = pve->score + tve.ascr + tve.lscr;
if ((tve.score - vh->wbeam) >= vh->bestscore[vh->n_frm]) {
tve.pred = i;
tve.lmstate.lm3g.lwid[1] = pve->lmstate.lm3g.lwid[0];
vithist_enter (vh, kbc, &tve);
}
}
}
}
}
void
vithist_rescore(vithist_t * vh, ngram_model_t *lm,
s3dict_t *dict, dict2pid_t *dict2pid,
fillpen_t *fp,
s3wid_t wid, int32 ef, int32 score,
int32 pred, int32 type, int32 rc)
{
vithist_entry_t *pve, tve;
int32 lwid;
int32 se, fe;
int32 i;
assert(vh->n_frm == ef);
if (pred == -1) {
/* Always do E_FATAL assuming upper level function take care of error checking. */
E_FATAL
("Hmm->out.history equals to -1 with score %d, some active phone was not computed?\n",
score);
}
/* pve is the previous entry before word with wid or, se an fe is the
first to the last entry before pve. So pve is w_{n-1} */
pve = vithist_id2entry(vh, pred);
/* Create a temporary entry with all the info currently available */
tve.wid = wid;
tve.sf = pve->ef + 1;
tve.ef = ef;
tve.type = type;
tve.valid = 1;
tve.ascr = score - pve->path.score;
tve.lscr = 0;
tve.rc = NULL;
tve.n_rc = 0;
/* Filler words only have unigram language model scores, so not
* much special needs to be done for them. vithist_prune() is
* going to prune out most of these later on, anyway. */
if (s3dict_filler_word(dict, wid)) {
tve.path.score = score;
tve.lscr = fillpen(fp, wid);
tve.path.score += tve.lscr;
if ((tve.path.score - vh->wbeam) >= vh->bestscore[vh->n_frm]) {
tve.path.pred = pred;
/* Note that they just propagate the same LM state since
* they are not in the LM. */
tve.lmstate.lm3g = pve->lmstate.lm3g;
vithist_enter(vh, dict, dict2pid, &tve, rc);
}
}
else {
if (pred == 0) { /* Special case for the initial <s> entry */
se = 0;
fe = 1;
}
else {
se = vh->frame_start[pve->ef];
fe = vh->frame_start[pve->ef + 1];
}
/* Now if it is a word, backtrack again to get all possible previous word
So pve becomes the w_{n-2}.
*/
lwid = ngram_wid(lm, s3dict_wordstr(dict, s3dict_basewid(dict, wid)));
tve.lmstate.lm3g.lwid[0] = lwid;
/* FIXME: This loop is completely awful. For each entry in
* this frame, we scan every entry in the previous frame,
* potentially creating a new history entry. This means that
* without pruning, the size of the vithist table (and thus
* the time taken here) is exponential in the number of
* frames! */
for (i = se; i < fe; i++) {
pve = vithist_id2entry(vh, i);
if (pve->valid) {
int n_used;
tve.path.score = pve->path.score + tve.ascr;
/* Try at all costs to avoid calling ngram_tg_score()
* because it is the main time consuming part here
* (but as noted above... ugh...) See below as well. */
if ((tve.path.score - vh->wbeam) < vh->bestscore[vh->n_frm])
continue;
/* The trigram cache is supposed to make this fast,
* but due to the crazy number of times this could be
* called, it's still slow compared to a hash
* table. */
tve.lscr = ngram_tg_score(lm, lwid, pve->lmstate.lm3g.lwid[0],
pve->lmstate.lm3g.lwid[1], &n_used);
tve.path.score += tve.lscr;
/* A different word exit threshold - we would have to
* be inside the general word beam in order to get
* here, now we apply a second beam to the *vithist
* entries* in this frame. There can be an ungodly
* number of them for reasons that aren't entirely
* clear to me, so this is kind of a pre-pruning.
* NOTE: the "backwards" math here is because
* vh->bestscore is frequently MAX_NEG_INT32. ALSO
* NOTE: We can't precompute the threshold since the
* best score will be updated by vithist_enter(). */
if ((tve.path.score - vh->wbeam) >= vh->bestscore[vh->n_frm]) {
tve.path.pred = i;
tve.lmstate.lm3g.lwid[1] = pve->lmstate.lm3g.lwid[0];
vithist_enter(vh, dict, dict2pid, &tve, rc);
}
}
}
}
}
