libsent/src/phmm/gprune_safe.c

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/*
 * Copyright (c) 1991-2007 Kawahara Lab., Kyoto University
 * Copyright (c) 2000-2005 Shikano Lab., Nara Institute of Science and Technology
 * Copyright (c) 2005-2007 Julius project team, Nagoya Institute of Technology
 * All rights reserved
 */

/* gprune_safe.c --- calculate probability of Gaussian densities */
/*                   with Gaussian pruning (safe) */

/* $Id: gprune_safe.c,v 1.1.1.1 2007/09/28 02:50:56 sumomo Exp $ */

#include <sent/stddefs.h>
#include <sent/htk_hmm.h>
#include <sent/htk_param.h>
#include <sent/hmm.h>
#include <sent/hmm_calc.h>

LOGPROB
compute_g_safe(HMMWork *wrk, HTK_HMM_Dens *binfo, LOGPROB thres)
{
  VECT tmp, x;
  VECT *mean;
  VECT *var;
  VECT *vec = wrk->OP_vec;
  short veclen = wrk->OP_veclen;
  VECT fthres = thres * (-2.0);

  if (binfo == NULL) return(LOG_ZERO);
  mean = binfo->mean;
  var = binfo->var->vec;
  tmp = binfo->gconst;
  for (; veclen > 0; veclen--) {
    x = *(vec++) - *(mean++);
    tmp += x * x * *(var++);
    if (tmp > fthres)  return LOG_ZERO;
  }
  return(tmp * -0.5);
}



boolean
gprune_safe_init(HMMWork *wrk)
{
  int i;

  /* maximum Gaussian set size = maximum mixture size */
  wrk->OP_calced_maxnum = wrk->OP_hmminfo->maxmixturenum;
  wrk->OP_calced_score = (LOGPROB *)mymalloc(sizeof(LOGPROB) * wrk->OP_gprune_num);
  wrk->OP_calced_id = (int *)mymalloc(sizeof(int) * wrk->OP_gprune_num);
  wrk->mixcalced = (boolean *)mymalloc(sizeof(int) * wrk->OP_calced_maxnum);
  for(i=0;i<wrk->OP_calced_maxnum;i++) wrk->mixcalced[i] = FALSE;
  return TRUE;
}

void
gprune_safe_free(HMMWork *wrk)
{
  free(wrk->OP_calced_score);
  free(wrk->OP_calced_id);
  free(wrk->mixcalced);
}

void
gprune_safe(HMMWork *wrk, HTK_HMM_Dens **g, int gnum, int *last_id)
{
  int i, j, num = 0;
  LOGPROB score, thres;

  if (last_id != NULL) {        /* compute them first to form threshold */
    /* 1. calculate first $OP_gprune_num and set initial threshold */
    for (j=0; j<wrk->OP_gprune_num; j++) {
      i = last_id[j];
      score = compute_g_base(wrk, g[i]);
      num = cache_push(wrk, i, score, num);
      wrk->mixcalced[i] = TRUE;      /* mark them as calculated */
    }
    thres = wrk->OP_calced_score[num-1];
    /* 2. calculate the rest with pruning*/
    for (i = 0; i < gnum; i++) {
      /* skip calced ones in 1. */
      if (wrk->mixcalced[i]) {
        wrk->mixcalced[i] = FALSE;
        continue;
      }
      /* compute with safe pruning */
      score = compute_g_safe(wrk, g[i], thres);
      if (score <= thres) continue;
      num = cache_push(wrk, i, score, num);
      thres = wrk->OP_calced_score[num-1];
    }
  } else {                      /* in case the last_id not available */
    /* not tied-mixture, or at the first 0 frame */
    thres = LOG_ZERO;
    for (i = 0; i < gnum; i++) {
      if (num < wrk->OP_gprune_num) {
        score = compute_g_base(wrk, g[i]);
      } else {
        score = compute_g_safe(wrk, g[i], thres);
        if (score <= thres) continue;
      }
      num = cache_push(wrk, i, score, num);
      thres = wrk->OP_calced_score[num-1];
    }
  }
  wrk->OP_calced_num = num;
}

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