- initial import

src/libs/libg729/de_acelp.c

@@ -0,0 +1,73 @@
+/*
+   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  Decod_ACELP()                                  *
+ *  ~~~~~~~~~~~~~~~~~~~~~~~                                  *
+ *   Algebraic codebook decoder.                             *
+ *----------------------------------------------------------*/
+
+#include "typedef.h"
+#include "basic_op.h"
+#include "ld8a.h"
+
+void
+Decod_ACELP (Word16 sign,	/* (i)     : signs of 4 pulses.                       */
+	     Word16 index,	/* (i)     : Positions of the 4 pulses.               */
+	     Word16 cod[]	/* (o) Q13 : algebraic (fixed) codebook excitation    */
+  )
+{
+  Word16 i, j;
+  Word16 pos[4];
+
+
+  /* Decode the positions */
+
+  i = index & (Word16) 7;
+  pos[0] = add (i, shl (i, 2));	/* pos0 =i*5 */
+
+  index = shr (index, 3);
+  i = index & (Word16) 7;
+  i = add (i, shl (i, 2));	/* pos1 =i*5+1 */
+  pos[1] = add (i, 1);
+
+  index = shr (index, 3);
+  i = index & (Word16) 7;
+  i = add (i, shl (i, 2));	/* pos2 =i*5+1 */
+  pos[2] = add (i, 2);
+
+  index = shr (index, 3);
+  j = index & (Word16) 1;
+  index = shr (index, 1);
+  i = index & (Word16) 7;
+  i = add (i, shl (i, 2));	/* pos3 =i*5+3+j */
+  i = add (i, 3);
+  pos[3] = add (i, j);
+
+  /* decode the signs  and build the codeword */
+
+  for (i = 0; i < L_SUBFR; i++) {
+    cod[i] = 0;
+  }
+
+  for (j = 0; j < 4; j++) {
+
+    i = sign & (Word16) 1;
+    sign = shr (sign, 1);
+
+    if (i != 0) {
+      cod[pos[j]] = 8191;	/* Q13 +1.0 */
+    }
+    else {
+      cod[pos[j]] = -8192;	/* Q13 -1.0 */
+    }
+  }
+
+  return;
+}