shithub: opus

Info  •  Files  •  Log  •  Branches

More simplifications to the Viterbi code

--- a/libcelt/celt.c

+++ b/libcelt/celt.c

@@ -546,8 +546,8 @@

    int i, curr;

    celt_word16 threshold;

    VARDECL(celt_word16, metric);

-   VARDECL(celt_word16, cost0);

-   VARDECL(celt_word16, cost1);

+   celt_word16 cost0;

+   celt_word16 cost1;

    VARDECL(int, path0);

    VARDECL(int, path1);

    /* FIXME: lambda should depend on the bit-rate */

@@ -555,8 +555,6 @@

    SAVE_STACK;

    ALLOC(metric, len, celt_word16);

-   ALLOC(cost0, len, celt_word16);

-   ALLOC(cost1, len, celt_word16);

    ALLOC(path0, len, int);

    ALLOC(path1, len, int);

    for (i=0;i<len;i++)

@@ -571,38 +569,39 @@

    } else {

       threshold = QCONST16(.5f,DB_SHIFT);

    }

-   cost0[0] = 0;

-   cost1[0] = lambda;

+   cost0 = 0;

+   cost1 = lambda;

    /* Viterbi forward pass */

    for (i=1;i<len;i++)

    {

+      celt_word16 curr0, curr1;

       celt_word16 from0, from1;

-      cost1[i] = 0;

-      cost0[i] = metric[i]-threshold;

-      from0 = cost0[i-1];

-      from1 = cost1[i-1] + lambda;

+      from0 = cost0;

+      from1 = cost1 + lambda;

       if (from0 < from1)

       {

-         cost0[i] += from0;

+         curr0 = from0;

          path0[i]= 0;

       } else {

-         cost0[i] += from1;

+         curr0 = from1;

          path0[i]= 1;

       }

-      from0 = cost0[i-1] + lambda;

-      from1 = cost1[i-1];

+      from0 = cost0 + lambda;

+      from1 = cost1;

       if (from0 < from1)

       {

-         cost1[i] += from0;

+         curr1 = from0;

          path1[i]= 0;

       } else {

-         cost1[i] += from1;

+         curr1 = from1;

          path1[i]= 1;

       }

+      cost0 = curr0 + (metric[i]-threshold);

+      cost1 = curr1;

    }

-   tf_res[len-1] = cost0[len-1] < cost1[len-1] ? 0 : 1;

+   tf_res[len-1] = cost0 < cost1 ? 0 : 1;

    /* Viterbi backward pass to check the decisions */

    for (i=len-2;i>=0;i--)

    {