1 /* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
18 /****************************************************************************************
19 Portions of this file are derived from the following 3GPP standard:
22 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
23 Available from http://www.3gpp.org
25 (C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26 Permission to distribute, modify and use this file under the standard license
27 terms listed above has been obtained from the copyright holder.
28 ****************************************************************************************/
30 ------------------------------------------------------------------------------
36 ------------------------------------------------------------------------------
40 Purpose : Lag windowing of autocorrelations.
42 ------------------------------------------------------------------------------
47 #define levinson_h "$Id $"
49 /*----------------------------------------------------------------------------
51 ----------------------------------------------------------------------------*/
55 /*--------------------------------------------------------------------------*/
61 /*----------------------------------------------------------------------------
63 ; [Define module specific macros here]
64 ----------------------------------------------------------------------------*/
66 /*----------------------------------------------------------------------------
68 ; [Include all pre-processor statements here.]
69 ----------------------------------------------------------------------------*/
71 /*----------------------------------------------------------------------------
72 ; EXTERNAL VARIABLES REFERENCES
73 ; [Declare variables used in this module but defined elsewhere]
74 ----------------------------------------------------------------------------*/
76 /*----------------------------------------------------------------------------
78 ----------------------------------------------------------------------------*/
80 /*----------------------------------------------------------------------------
81 ; ENUMERATED TYPEDEF'S
82 ----------------------------------------------------------------------------*/
84 /*----------------------------------------------------------------------------
85 ; STRUCTURES TYPEDEF'S
86 ----------------------------------------------------------------------------*/
89 Word16 old_A[M + 1]; /* Last A(z) for case of unstable filter */
92 /*----------------------------------------------------------------------------
93 ; GLOBAL FUNCTION DEFINITIONS
94 ; [List function prototypes here]
95 ----------------------------------------------------------------------------*/
96 Word16 Levinson_init(LevinsonState **st);
97 /* initialize one instance of the pre processing state.
98 Stores pointer to filter status struct in *st. This pointer has to
99 be passed to Levinson in each call.
103 Word16 Levinson_reset(LevinsonState *st);
104 /* reset of pre processing state (i.e. set state memory to zero)
107 void Levinson_exit(LevinsonState **st);
108 /* de-initialize pre processing state (i.e. free status struct)
114 Word16 Rh[], /* i : Rh[m+1] Vector of autocorrelations (msb) */
115 Word16 Rl[], /* i : Rl[m+1] Vector of autocorrelations (lsb) */
116 Word16 A[], /* o : A[m] LPC coefficients (m = 10) */
117 Word16 rc[], /* o : rc[4] First 4 reflection coefficients */
127 #endif /* _LEVINSON_H_ */