1/* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
3 *
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
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
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
13 * express or implied.
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
17 */
18/****************************************************************************************
19Portions of this file are derived from the following 3GPP standard:
20
21    3GPP TS 26.073
22    ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
23    Available from http://www.3gpp.org
24
25(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26Permission to distribute, modify and use this file under the standard license
27terms listed above has been obtained from the copyright holder.
28****************************************************************************************/
29/*
30------------------------------------------------------------------------------
31
32
33
34 Pathname: ./audio/gsm-amr/c/src/preemph.c
35 Functions:
36
37     Date: 02/04/2002
38
39------------------------------------------------------------------------------
40 REVISION HISTORY
41
42 Description: Removed the functions preemphasis_init and preemphasis_exit.
43 The preemphasis related structure is no longer dynamically allocated.
44 Placed file in the appropriate PV Software Template format.
45
46 Description: Changed to accept the pOverflow flag for EPOC compatibility.
47
48 Description:  Replaced OSCL mem type functions and eliminated include
49               files that now are chosen by OSCL definitions
50
51 Description:  Replaced "int" and/or "char" with OSCL defined types.
52
53 Description:
54
55------------------------------------------------------------------------------
56 MODULE DESCRIPTION
57
58 Purpose          : Preemphasis filtering
59 Description      : Filtering through 1 - g z^-1
60
61------------------------------------------------------------------------------
62*/
63
64/*----------------------------------------------------------------------------
65; INCLUDES
66----------------------------------------------------------------------------*/
67#include "preemph.h"
68#include "typedef.h"
69#include "basic_op.h"
70
71/*----------------------------------------------------------------------------
72; MACROS
73; Define module specific macros here
74----------------------------------------------------------------------------*/
75
76/*----------------------------------------------------------------------------
77; DEFINES
78; Include all pre-processor statements here. Include conditional
79; compile variables also.
80----------------------------------------------------------------------------*/
81
82/*----------------------------------------------------------------------------
83; LOCAL FUNCTION DEFINITIONS
84; Function Prototype declaration
85----------------------------------------------------------------------------*/
86
87/*----------------------------------------------------------------------------
88; LOCAL VARIABLE DEFINITIONS
89; Variable declaration - defined here and used outside this module
90----------------------------------------------------------------------------*/
91
92
93/*
94------------------------------------------------------------------------------
95 FUNCTION NAME:  preemphasis_reset
96------------------------------------------------------------------------------
97 INPUT AND OUTPUT DEFINITIONS
98
99 Inputs:
100    st -- double pointer to preemphasisState
101
102 Outputs:
103    st -- double ponter to preemphasisState
104
105 Returns:
106    -1 if an error occurs
107     0 if OK
108
109 Global Variables Used:
110    None
111
112 Local Variables Needed:
113    None
114
115------------------------------------------------------------------------------
116 FUNCTION DESCRIPTION
117
118    Initializes state memory to zero
119------------------------------------------------------------------------------
120 REQUIREMENTS
121
122 None
123
124------------------------------------------------------------------------------
125 REFERENCES
126
127 preemph.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
128
129------------------------------------------------------------------------------
130 PSEUDO-CODE
131
132
133------------------------------------------------------------------------------
134 RESOURCES USED [optional]
135
136 When the code is written for a specific target processor the
137 the resources used should be documented below.
138
139 HEAP MEMORY USED: x bytes
140
141 STACK MEMORY USED: x bytes
142
143 CLOCK CYCLES: (cycle count equation for this function) + (variable
144                used to represent cycle count for each subroutine
145                called)
146     where: (cycle count variable) = cycle count for [subroutine
147                                     name]
148
149------------------------------------------------------------------------------
150 CAUTION [optional]
151 [State any special notes, constraints or cautions for users of this function]
152
153------------------------------------------------------------------------------
154*/
155
156Word16 preemphasis_reset(preemphasisState *state)
157{
158    if (state == (preemphasisState *) NULL)
159    {
160        /* fprintf(stderr, "preemphasis_reset: invalid parameter\n"); */
161        return -1;
162    }
163
164    state->mem_pre = 0;
165
166    return 0;
167}
168
169/*
170------------------------------------------------------------------------------
171 FUNCTION NAME:  preemphasis
172------------------------------------------------------------------------------
173 INPUT AND OUTPUT DEFINITIONS
174
175 Inputs:
176    st -- Pointer to preemphasisState -- preemphasis filter state
177    signal -- array of type Word16 -- input signal overwritten by the output
178    g -- Word16 -- preemphasis coefficient
179    L -- Word16 -- size of filtering
180
181 Outputs:
182    st -- Pointer to preemphasisState -- preemphasis filter state
183    signal -- array of type Word16 -- input signal overwritten by the output
184    pOverflow -- pointer to type Flag -- overflow indicator
185 Returns:
186    None
187
188 Global Variables Used:
189    None
190
191 Local Variables Needed:
192    None
193
194------------------------------------------------------------------------------
195 FUNCTION DESCRIPTION
196
197    Filtering through 1 - g z^-1
198------------------------------------------------------------------------------
199 REQUIREMENTS
200
201 None
202
203------------------------------------------------------------------------------
204 REFERENCES
205
206 preemph.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
207
208------------------------------------------------------------------------------
209 PSEUDO-CODE
210
211
212------------------------------------------------------------------------------
213 RESOURCES USED [optional]
214
215 When the code is written for a specific target processor the
216 the resources used should be documented below.
217
218 HEAP MEMORY USED: x bytes
219
220 STACK MEMORY USED: x bytes
221
222 CLOCK CYCLES: (cycle count equation for this function) + (variable
223                used to represent cycle count for each subroutine
224                called)
225     where: (cycle count variable) = cycle count for [subroutine
226                                     name]
227
228------------------------------------------------------------------------------
229 CAUTION [optional]
230 [State any special notes, constraints or cautions for users of this function]
231
232------------------------------------------------------------------------------
233*/
234
235
236void preemphasis(
237    preemphasisState *st, /* (i/o) : preemphasis filter state               */
238    Word16 *signal,       /* (i/o) : input signal overwritten by the output */
239    Word16 g,             /* (i)   : preemphasis coefficient                */
240    Word16 L,             /* (i)   : size of filtering                      */
241    Flag  *pOverflow      /* (o)   : overflow indicator                     */
242)
243{
244    Word16 *p1;
245    Word16 *p2;
246    Word16 temp;
247    Word16 temp2;
248    Word16 i;
249
250    p1 = signal + L - 1;
251    p2 = p1 - 1;
252    temp = *p1;
253
254    for (i = 0; i <= L - 2; i++)
255    {
256        temp2 = mult(g, *(p2--), pOverflow);
257        *p1 = sub(*p1, temp2, pOverflow);
258
259        p1--;
260    }
261
262    temp2 = mult(g, st->mem_pre, pOverflow);
263
264    *p1 = sub(*p1, temp2, pOverflow);
265
266    st->mem_pre = temp;
267
268    return;
269}
270
271
272
273