- work on evs decoder

src/libs/libevs/lib_com/weight_a.cpp

@@ -0,0 +1,73 @@
+/*====================================================================================
+    EVS Codec 3GPP TS26.443 Nov 13, 2018. Version 12.11.0 / 13.7.0 / 14.3.0 / 15.1.0
+  ====================================================================================*/
+
+#include "options.h"
+#include "prot.h"
+
+/*------------------------------------------------------------------
+ * weight_a()
+ *
+ * Weighting of LP filter coefficients, ap[i] = a[i] * (gamma^i)
+ *------------------------------------------------------------------*/
+
+void weight_a(
+    const float *a,     /* i  : LP filter coefficients          */
+    float *ap,    /* o  : weighted LP filter coefficients */
+    const float gamma,  /* i  : weighting factor                */
+    const short m       /* i  : order of LP filter              */
+)
+{
+    float f;
+    short i;
+
+    ap[0] = a[0];
+    f = gamma;
+
+    for (i = 1; i <= m; i++)
+    {
+        ap[i] = f*a[i];
+        f *= gamma;
+    }
+
+    return;
+}
+
+
+
+/*------------------------------------------------------------------
+ * weight_a_subfr()
+ *
+ * Weighting of LP filter coefficients for multiple subframes,
+ * ap[i] = a[i] * (gamma^i)
+ *------------------------------------------------------------------*/
+
+void weight_a_subfr(
+    const short nb_subfr,   /* i  : number of subframes             */
+    const float *A,         /* i  : LP filter coefficients          */
+    float *Aw,        /* o  : weighted LP filter coefficients */
+    const float gamma,      /* i  : weighting factor                */
+    const short m           /* i  : order of LP filter              */
+)
+{
+    short i, j;
+    float tmp;
+
+    for( j=0; j<nb_subfr; j++ )
+    {
+        Aw[j*(m+1)] = A[j*(m+1)];
+    }
+
+    /* Smoothing aka spreading aka masking envelope generation */
+    tmp = gamma;
+    for( i = 1; i < m+1; i++ )
+    {
+        for( j=0; j<nb_subfr; j++ )
+        {
+            Aw[i+j*(m+1)] = A[i+j*(m+1)] * tmp;
+        }
+        tmp *= gamma;
+    }
+
+    return;
+}