documented fast search algorithm, working fore newamp1

Author: drowe67

src/mbest.c

@@ -66,7 +66,7 @@ void mbest_destroy(struct MBEST *mbest) {
 
 /* precompyte table for efficient VQ search */
 
-void mbest_precompute_cbsq(float cbsq[], float cb[], int k, int m) {
+void mbest_precompute_cbsq(float cbsq[], const float cb[], int k, int m) {
     for (int j=0; j<m; j++) {
         cbsq[j] = 0.0;
         for(int i=0; i<k; i++)
@@ -132,79 +132,60 @@ void mbest_search(
 		  int           index[] /* indexes that lead us here     */
 )
 {
-   float   e;
-   int     j;
+   int j;
 
+   float vecsq = 0.0;
+   for(int i=0; i<k; i++)
+       vecsq += vec[i]*vec[i];
+   
    for(j=0; j<m; j++) {
-        float   diff;
-        int i;
 
         /*
-        float cbsq = 0.0;
-        for(int i = 0; i < k; i++) {
-            cbsq += cb[j*k+i]*cb[j*k+i];
-        }
-        */
-        /*
-	e = 0.0;
-	for(i=0; i<k; i++) {
-	    diff = cb[j*k+i]-vec[i];
-	    e += diff*w[i]*diff*w[i];
-	}
+          float e = 0.0;
+          for(i=0; i<k; i++)
+             e += (cb[j*k+i] - vec[i])*(cb[j*k+i] - vec[i]);
+
+           |
+          \|/
+
+          float e = 0.0;
+          for(i=0; i<k; i++)
+             e += cb[j*k+i]*cb[j*k+i] - 2*cb[j*k+i]*vec[i] + vec[i]*vec[i];
+          
+           |
+          \|/
+
+          float e = 0.0; float corr = 0.0;
+          for(i=0; i<k; i++)
+             e += cb[j*k+i]*cb[j*k+i];    .... (1)
+          for(i=0; i<k; i++)
+             e -= 2*cb[j*k+i]*vec[i];     .... (2)
+          for(i=0; i<k; i++)
+             e += vec[i]*vec[i];          .... (3)
+     
+          (1) can be precomputed, so we just need to compute (2) for each search, 
+          (3) can be computed outside the search loop
         */
+
         float corr = 0.0;
-	for(i=0; i<k; i++)
+	for(int i=0; i<k; i++)
 	    corr += cb[j*k+i]*vec[i];
-        float e = cbsq[j] - 2*corr;
+        float e = cbsq[j] - 2*corr + vecsq;
+        
 	index[0] = j;
         if (e < mbest->list[mbest->entries - 1].error)
 	    mbest_insert(mbest, index, e);
    }
 }
 
-/*---------------------------------------------------------------------------*\
-
-  mbest_search_equalweight
-
-  Searches vec[] to a codebbook of vectors, and maintains a list of the mbest
-  closest matches. Similar to mbest_search() but with w[] = 1.
-
-\*---------------------------------------------------------------------------*/
-
-void mbest_search_equalweight(
-		  const float  *cb,     /* VQ codebook to search         */
-		  float         vec[],  /* target vector                 */
-		  int           k,      /* dimension of vector           */
-		  int           m,      /* number on entries in codebook */
-		  struct MBEST *mbest,  /* list of closest matches       */
-		  int           index[] /* indexes that lead us here     */
-)
-{
-   float   e;
-   
-   for(int j = 0; j < m; j++) {
-        e = 0.0;
-        for(int i = 0; i < k; i++) {
-            float diff = (*cb++) - vec[i];
-            float diff2 = diff * diff;
-            e += diff2;
-        }
-
-        index[0] = j;
-        if (e < mbest->list[mbest->entries - 1].error)
-            mbest_insert(mbest, index, e);
-   }
-}
-
-
 /*---------------------------------------------------------------------------*\
 
   mbest_search450
 
   Searches vec[] to a codebbook of vectors, and maintains a list of the mbest
   closest matches. Only searches the first NewAmp2_K Vectors
 
-  \*---------------------------------------------------------------------------*/
+\*---------------------------------------------------------------------------*/
 
 void mbest_search450(const float  *cb, float vec[], float w[], int k,int shorterK, int m, struct MBEST *mbest, int index[])
 

src/mbest.h

@@ -44,10 +44,9 @@ struct MBEST {
 
 struct MBEST *mbest_create(int entries);
 void mbest_destroy(struct MBEST *mbest);
-void mbest_precompute_cbsq(float cbsq[], float cb[], int k, int m);
+void mbest_precompute_cbsq(float cbsq[], const float cb[], int k, int m);
 void mbest_insert(struct MBEST *mbest, int index[], float error);
-void mbest_search(const float  *cb, const float  *cbsq, float vec[], float w[], int k, int m, struct MBEST *mbest, int index[]);
-void mbest_search_equalweight(const float  *cb, float vec[], int k, int m, struct MBEST *mbest, int index[]);
+void mbest_search(const float  *cb, const float *cbsq, float vec[], float w[], int k, int m, struct MBEST *mbest, int index[]);
 void mbest_search450(const float  *cb, float vec[], float w[], int k,int shorterK, int m, struct MBEST *mbest, int index[]);
 
 void mbest_print(char title[], struct MBEST *mbest);

src/newamp1.c

@@ -174,7 +174,7 @@ float rate_K_mbest_encode(int *indexes, float *x, float *xq, int ndim, int mbest
 
   /* precompute tables for efficient search */
   mbest_precompute_cbsq(codebook1sq, codebook1, newamp1vq_cb[0].k, newamp1vq_cb[0].m);
-  mbest_precompute_cbsq(codebook2sq, codebook2, newamp1vq_cb[0].k, newamp1vq_cb[0].m);
+  mbest_precompute_cbsq(codebook2sq, codebook2, newamp1vq_cb[1].k, newamp1vq_cb[1].m);
 
   /* codebook is compiled for a fixed K */