From ac7c48b4dee99d4c772f133d70d8d1b38262fcd2 Mon Sep 17 00:00:00 2001
From: Author Name <david@rowetel.com>
Date: Fri, 7 Jul 2023 12:20:59 +0930
Subject: shallow zip-file copy from codec2 e9d726bf20

---
 src/mbest.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 197 insertions(+)
 create mode 100644 src/mbest.c

(limited to 'src/mbest.c')

diff --git a/src/mbest.c b/src/mbest.c
new file mode 100644
index 0000000..8651e70
--- /dev/null
+++ b/src/mbest.c
@@ -0,0 +1,197 @@
+/*---------------------------------------------------------------------------*\
+
+  FILE........: mbest.c
+  AUTHOR......: David Rowe
+  DATE CREATED: Jan 2017
+
+  Multistage vector quantiser search algorithm that keeps multiple
+  candidates from each stage.
+
+\*---------------------------------------------------------------------------*/
+
+/*
+  Copyright David Rowe 2017
+
+  All rights reserved.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License version 2.1, as
+  published by the Free Software Foundation.  This program is
+  distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+  License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "mbest.h"
+
+struct MBEST *mbest_create(int entries) {
+    int           i,j;
+    struct MBEST *mbest;
+
+    assert(entries > 0);
+    mbest = (struct MBEST *)malloc(sizeof(struct MBEST));
+    assert(mbest != NULL);
+
+    mbest->entries = entries;
+    mbest->list = (struct MBEST_LIST *)malloc(entries*sizeof(struct MBEST_LIST));
+    assert(mbest->list != NULL);
+
+    for(i=0; i<mbest->entries; i++) {
+	for(j=0; j<MBEST_STAGES; j++)
+	    mbest->list[i].index[j] = 0;
+	mbest->list[i].error = 1E32;
+    }
+
+    return mbest;
+}
+
+
+void mbest_destroy(struct MBEST *mbest) {
+    assert(mbest != NULL);
+    free(mbest->list);
+    free(mbest);
+}
+
+
+/* apply weighting to VQ for efficient VQ search */
+
+void mbest_precompute_weight(float cb[], float w[], int k, int m) {
+    for (int j=0; j<m; j++) {
+        for(int i=0; i<k; i++)
+            cb[k*j+i] *= w[i];
+    }
+}
+
+/*---------------------------------------------------------------------------*\
+
+  mbest_insert
+
+  Insert the results of a vector to codebook entry comparison. The
+  list is ordered in order of error, so those entries with the
+  smallest error will be first on the list.
+
+\*---------------------------------------------------------------------------*/
+
+void mbest_insert(struct MBEST *mbest, int index[], float error) {
+    int                i, found;
+    struct MBEST_LIST *list    = mbest->list;
+    int                entries = mbest->entries;
+
+    found = 0;
+    for(i=0; i<entries && !found; i++)
+	if (error < list[i].error) {
+	    found = 1;
+            memmove(&list[i+1], &list[i], sizeof(struct MBEST_LIST) * (entries - i - 1));
+            memcpy(&list[i].index[0], &index[0], sizeof(int) * MBEST_STAGES);
+	    list[i].error = error;
+	}
+}
+
+
+void mbest_print(char title[], struct MBEST *mbest) {
+    int i,j;
+
+    fprintf(stderr, "%s\n", title);
+    for(i=0; i<mbest->entries; i++) {
+	for(j=0; j<MBEST_STAGES; j++)
+	    fprintf(stderr, "  %4d ", mbest->list[i].index[j]);
+	fprintf(stderr, " %f\n", (double)mbest->list[i].error);
+    }
+}
+
+
+/*---------------------------------------------------------------------------*\
+
+  mbest_search
+
+  Searches vec[] to a codebbook of vectors, and maintains a list of the mbest
+  closest matches.
+
+\*---------------------------------------------------------------------------*/
+
+void mbest_search(
+		  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     */
+)
+{
+    int j;
+
+    /* note weighting can be applied externally by modifiying cb[] and vec:
+
+      float e = 0.0;
+      for(i=0; i<k; i++)
+        e += pow(w[i]*(cb[j*k+i] - vec[i]),2.0)
+           
+       |
+      \|/
+
+      for(i=0; i<k; i++)
+         e += pow(w[i]*cb[j*k+i] - w[i]*vec[i]),2.0)
+
+       |
+      \|/
+
+      for(i=0; i<k; i++)
+         e += pow(cb1[j*k+i] - vec1[i]),2.0)
+
+      where cb1[j*k+i] = w[i]*cb[j*k+i], and vec1[i] = w[i]*vec[i]
+    */
+
+    for(j=0; j<m; j++) {
+        float e = 0.0;
+        for(int i=0; i<k; i++) {
+	    float diff = *cb++ - vec[i];
+            e += diff*diff;
+        }
+        
+        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[])
+
+{
+    float   e;
+    int     i,j;
+    float   diff;
+
+    for(j=0; j<m; j++) {
+	e = 0.0;
+	for(i=0; i<k; i++) {
+            //Only search first NEWAMP2_K Vectors
+            if(i<shorterK){
+                diff = cb[j*k+i]-vec[i];
+                e += diff*w[i] * diff*w[i];
+            }
+	}
+	index[0] = j;
+	mbest_insert(mbest, index, e);
+    }
+}
+   
-- 
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