- work on evs decoder

src/libs/libevs/lib_com/enr_1_az.cpp

@@ -0,0 +1,30 @@
+/*====================================================================================
+    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 "cnst.h"
+#include "prot.h"
+
+/*-------------------------------------------------------------------*
+ * enr_1_Az()
+ *
+ * Find Energy of the 1/A(z) impulse response
+ *-------------------------------------------------------------------*/
+
+float enr_1_Az(        /* o  : impulse response energy */
+    const float Aq[],  /* i  : LP filter coefs         */
+    const short len    /* i  : impulse response length */
+)
+{
+    float enr_LP, h1[2*L_SUBFR], mem[M];
+
+
+    set_f( h1, 0, len );                          /* Find the impulse response        */
+    set_f( mem, 0, M );
+    h1[0] = 1.0f;
+    syn_filt( Aq, M, h1, h1, len, mem, 0 );
+    enr_LP = dotp( h1, h1, len ) + 0.01f;         /* Find the impulse response energy */
+
+    return enr_LP;
+}