- work on evs decoder

src/libs/libevs/lib_com/ppp.cpp

@@ -0,0 +1,83 @@
+/*====================================================================================
+    EVS Codec 3GPP TS26.443 Nov 13, 2018. Version 12.11.0 / 13.7.0 / 14.3.0 / 15.1.0
+  ====================================================================================*/
+
+#include <math.h>
+#include "cnst.h"
+#include "options.h"
+#include "prot.h"
+#include "rom_com.h"
+
+
+/*-------------------------------------------------------------------*
+ * Interpol_delay()
+ *
+ * Interpolation of pitch lag
+ *--------------------------------------------------------------------*/
+
+void Interpol_delay(
+    float *out,            /* o : pitch interpolation output   */
+    float *last,           /* i : last frame pitch lag         */
+    float *current,        /* i : current frame pitch lag      */
+    short SubNum,          /* i : subframe number              */
+    const float *frac            /* i : interpolation constant       */
+)
+{
+    out[0] = (1.0f - frac[SubNum]) **last + frac[SubNum] **current;
+    out[1] = (1.0f - frac[SubNum + 1]) **last + frac[SubNum + 1] **current;
+    out[2] = (1.0f - frac[SubNum + 2]) **last + frac[SubNum + 2] **current;
+
+    return;
+}
+
+
+/*-------------------------------------------------------------------*
+ * deemph_lpc()
+ *
+ * De-emphasis of LP coefficients
+ * convolve LPC with [1 -PREEMPH_FAC] to de-emphasise LPC
+ *--------------------------------------------------------------------*/
+
+void deemph_lpc(
+    float *p_Aq_curr,           /* i : LP coefficients current frame                 */
+    float *p_Aq_old,            /* i : LP coefficients previous frame                */
+    float *LPC_de_curr,         /* o : De-emphasized LP coefficients current frame   */
+    float *LPC_de_old           /* o : De-emphasized LP coefficients previous frame  */
+    ,short deemph_old
+
+)
+{
+    short k;
+    float b[M+2];
+    float a[2] = {-PREEMPH_FAC,1.0};
+
+    b[0] = 1.0;
+    for(k = 0; k < M; k++)
+    {
+        b[k+1] = p_Aq_curr[k];
+    }
+    b[M+1] = 0.0;
+
+    for(k = 0; k <= M; k++)
+    {
+        LPC_de_curr[k] = a[0]*b[k] + a[1]*b[k+1];
+    }
+
+    if ( deemph_old == 1)
+    {
+        /* ignoring the 1st value which is 1.0 in this case */
+        b[0] = 1.0;
+        for(k = 0; k < M; k++)
+        {
+            b[k+1] = p_Aq_old[k+1];
+        }
+        b[M+1] = 0.0;
+
+        for(k = 0; k <= M; k++)
+        {
+            LPC_de_old[k] = a[0]*b[k] + a[1]*b[k+1];
+        }
+    }
+
+    return;
+}