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optimisation: reworked intra_prediction() so that yy is computed fully only

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once and then updated for each iteration
This commit is contained in:
Jean-Marc Valin 2008-04-16 10:43:32 +10:00
parent 0a864645f9
commit a66c320871
1 changed files with 17 additions and 9 deletions
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26
libcelt/vq.c
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@ -280,6 +280,7 @@ void intra_prediction(celt_norm_t *x, celt_mask_t *W, int N, int K, celt_norm_t
celt_word32_t E;
celt_word16_t pred_gain;
int max_pos = N0-N;
celt_word32_t yy=0;
VARDECL(celt_norm_t, Xr);
SAVE_STACK;
@ -293,21 +294,21 @@ void intra_prediction(celt_norm_t *x, celt_mask_t *W, int N, int K, celt_norm_t
for (j=0;j<N;j++)
Xr[B*N-B*j-B+c] = x[B*j+c];
/* Compute yy for i=0 */
j=0;
do {
yy = MAC16_16(yy, Y[j], Y[j]);
} while (++j<B*N); /* Promises we loop at least once */
for (i=0;i<max_pos;i++)
{
celt_word32_t xy=0, yy=0;
celt_word16_t num;
celt_word16_t den;
celt_word32_t xy=0;
celt_word16_t num, den;
const celt_word16_t * restrict xp = Xr;
const celt_word16_t * restrict yp = Y+B*i;
/* OPT: If this doesn't generate a double-MAC (on supported architectures),
complain to your compilor vendor */
j=0;
do {
xy = MAC16_16(xy, *xp, *yp);
yy = MAC16_16(yy, *yp, *yp);
xp++;
yp++;
xy = MAC16_16(xy, *xp++, *yp++);
} while (++j<B*N); /* Promises we loop at least once */
/* Using xy^2/yy as the score but without having to do the division */
num = MULT16_16_Q15(ROUND16(xy,14),ROUND16(xy,14));
@ -322,6 +323,13 @@ void intra_prediction(celt_norm_t *x, celt_mask_t *W, int N, int K, celt_norm_t
/* Store xy as the sign. We'll normalise it to +/- 1 later. */
s = ROUND16(xy,14);
}
/* Update yy for the next iteration */
yp = Y+B*i;
j=0;
do {
yy = yy - MULT16_16(*yp, *yp) + MULT16_16(yp[B*N], yp[B*N]);
yp++;
} while (++j<B);
}
if (s<0)
{