- initial import

src/libs/libg729/dec_lag3.c

@@ -0,0 +1,79 @@
+/*
+   ITU-T G.729A Speech Coder    ANSI-C Source Code
+   Version 1.1    Last modified: September 1996
+
+   Copyright (c) 1996,
+   AT&T, France Telecom, NTT, Universite de Sherbrooke
+   All rights reserved.
+*/
+
+/*------------------------------------------------------------------------*
+ *    Function Dec_lag3                                                   *
+ *             ~~~~~~~~                                                   *
+ *   Decoding of fractional pitch lag with 1/3 resolution.                *
+ * See "Enc_lag3.c" for more details about the encoding procedure.        *
+ *------------------------------------------------------------------------*/
+
+#include "typedef.h"
+#include "basic_op.h"
+#include "ld8a.h"
+
+void
+Dec_lag3 (Word16 index,		/* input : received pitch index           */
+	  Word16 pit_min,	/* input : minimum pitch lag              */
+	  Word16 pit_max,	/* input : maximum pitch lag              */
+	  Word16 i_subfr,	/* input : subframe flag                  */
+	  Word16 * T0,		/* output: integer part of pitch lag      */
+	  Word16 * T0_frac	/* output: fractional part of pitch lag   */
+  )
+{
+  Word16 i;
+  Word16 T0_min, T0_max;
+
+  if (i_subfr == 0) {		/* if 1st subframe */
+    if (sub (index, 197) < 0) {
+      /* *T0 = (index+2)/3 + 19 */
+
+      *T0 = add (mult (add (index, 2), 10923), 19);
+
+      /* *T0_frac = index - *T0*3 + 58 */
+
+      i = add (add (*T0, *T0), *T0);
+      *T0_frac = add (sub (index, i), 58);
+    }
+    else {
+      *T0 = sub (index, 112);
+      *T0_frac = 0;
+    }
+
+  }
+
+  else {			/* second subframe */
+
+    /* find T0_min and T0_max for 2nd subframe */
+
+    T0_min = sub (*T0, 5);
+    if (sub (T0_min, pit_min) < 0) {
+      T0_min = pit_min;
+    }
+
+    T0_max = add (T0_min, 9);
+    if (sub (T0_max, pit_max) > 0) {
+      T0_max = pit_max;
+      T0_min = sub (T0_max, 9);
+    }
+
+    /* i = (index+2)/3 - 1 */
+    /* *T0 = i + t0_min;    */
+
+    i = sub (mult (add (index, 2), 10923), 1);
+    *T0 = add (i, T0_min);
+
+    /* t0_frac = index - 2 - i*3; */
+
+    i = add (add (i, i), i);
+    *T0_frac = sub (sub (index, 2), i);
+  }
+
+  return;
+}