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fixed-point: alg_quant() entirely converter -- may require revisiting...

--- a/libcelt/vq.c

+++ b/libcelt/vq.c

@@ -108,14 +108,13 @@

 /** All the info necessary to keep track of a hypothesis during the search */

 struct NBest {

-   float score;

-   float gain;

+   celt_word32_t score;

    int sign;

    int pos;

    int orig;

-   float xy;

-   float yy;

-   float yp;

+   celt_word32_t xy;

+   celt_word32_t yy;

+   celt_word32_t yp;

 };

 void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, celt_norm_t *P, celt_word16_t alpha, ec_enc *enc)

@@ -207,7 +206,7 @@

       }

       for (m=0;m<Lupdate;m++)

-         nbest[m]->score = -1e10f;

+         nbest[m]->score = -VERY_LARGE32;

       for (m=0;m<L2;m++)

       {

@@ -218,10 +217,10 @@

             for (sign=-1;sign<=1;sign+=2)

             {

                /*fprintf (stderr, "%d/%d %d/%d %d/%d\n", i, K, m, L2, j, N);*/

-               celt_word32_t tmp_xy, tmp_yy, tmp_yp;

-               celt_word16_t spj, aspj;

-               float score;

-               float g;

+               celt_word32_t Rxy, Ryy, Ryp;

+               celt_word16_t spj, aspj; /* Intermediate results */

+               celt_word32_t score;

+               celt_word32_t g;

                celt_word16_t s = SHL16(sign*pulsesAtOnce, yshift);

                /* All pulses at one location must have the same sign. */

@@ -231,15 +230,18 @@

                spj = MULT16_16_P14(s, P[j]);

                aspj = MULT16_16_P15(alpha, spj);

                /* Updating the sums of the new pulse(s) */

-               tmp_xy = xy[m] + MULT16_16(s,X[j])     - MULT16_16(MULT16_16_P15(alpha,spj),Rxp);

-               tmp_yy = yy[m] + 2*MULT16_16(s,y[m][j]) + MULT16_16(s,s)   +MULT16_16(aspj,MULT16_16_Q14(aspj,Rpp)) - 2*MULT16_32_Q14(aspj,yp[m]) - 2*MULT16_16(s,MULT16_16_Q14(aspj,P[j]));

-               tmp_yp = yp[m] + MULT16_16(spj, SUB16(QCONST16(1.f,14),MULT16_16_Q15(alpha,Rpp)));

+               Rxy = xy[m] + MULT16_16(s,X[j])     - MULT16_16(MULT16_16_P15(alpha,spj),Rxp);

+               Ryy = yy[m] + 2*MULT16_16(s,y[m][j]) + MULT16_16(s,s)   +MULT16_16(aspj,MULT16_16_Q14(aspj,Rpp)) - 2*MULT16_32_Q14(aspj,yp[m]) - 2*MULT16_16(s,MULT16_16_Q14(aspj,P[j]));

+               Ryp = yp[m] + MULT16_16(spj, SUB16(QCONST16(1.f,14),MULT16_16_Q15(alpha,Rpp)));

                /* Compute the gain such that ||p + g*y|| = 1 */

-               g = (approx_sqrt(NORM_SCALING_1*NORM_SCALING_1*tmp_yp*tmp_yp + tmp_yy - NORM_SCALING_1*tmp_yy*Rpp) - tmp_yp*NORM_SCALING_1)*approx_inv(tmp_yy);

+               g = DIV32(SHL32(celt_sqrt(MULT16_16(ROUND(Ryp,14),ROUND(Ryp,14)) + Ryy - MULT16_16(ROUND(Ryy,14),Rpp)) - ROUND(Ryp,14),14),ROUND(Ryy,14));

+               //g *= NORM_SCALING_1;

                /* Knowing that gain, what the error: (x-g*y)^2 

                   (result is negated and we discard x^2 because it's constant) */

-               score = 2.f*g*tmp_xy*NORM_SCALING_1 - g*g*tmp_yy;

+               /*score = 2.f*g*Rxy - 1.f*g*g*Ryy*NORM_SCALING_1;*/

+               score = 2*MULT16_32_Q14(ROUND(Rxy,14),g) -

+                     MULT16_32_Q14(EXTRACT16(MULT16_32_Q14(ROUND(Ryy,14),g)),g);

                if (score>nbest[Lupdate-1]->score)

                {

@@ -260,10 +262,9 @@

                   nbest[id]->pos = j;

                   nbest[id]->orig = m;

                   nbest[id]->sign = sign;

-                  nbest[id]->gain = g;

-                  nbest[id]->xy = tmp_xy;

-                  nbest[id]->yy = tmp_yy;

-                  nbest[id]->yp = tmp_yp;

+                  nbest[id]->xy = Rxy;

+                  nbest[id]->yy = Ryy;

+                  nbest[id]->yp = Ryp;

                }

             }

          }

@@ -270,7 +271,7 @@

       }

-      if (!(nbest[0]->score > -1e10f))

+      if (!(nbest[0]->score > -VERY_LARGE32))

          celt_fatal("Could not find any match in VQ codebook. Something got corrupted somewhere.");

       /* Only now that we've made the final choice, update ny/iny and others */

       for (k=0;k<Lupdate;k++)