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 /****************************************************************************************
19 Portions 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)
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 ****************************************************************************************/
29 /*
30 ------------------------------------------------------------------------------
31
32
33
34 Pathname: ./audio/gsm-amr/c/src/dec_lag6.c
35 Functions: Dec_lag6
36
37 Date: 01/31/2002
38
39 ------------------------------------------------------------------------------
40 REVISION HISTORY
41
42 Description:
43 (1) Updated to accept new parameter, Flag *pOverflow.
44 (2) Placed file in the proper PV Software template.
45
46 Description:
47 (1) Removed "count.h" and "basic_op.h" and replaced with individual include
48 files (add.h, sub.h, etc.)
49
50 Description:
51 (1) Removed optimization -- mult(i, 3, pOverflow) is NOT the same as adding
52 i to itself 3 times. The reason is because the mult function does a
53 right shift by 15, which will obliterate smaller numbers.
54
55 Description: Replaced "int" and/or "char" with OSCL defined types.
56
57 Description:
58
59 ------------------------------------------------------------------------------
60 INPUT AND OUTPUT DEFINITIONS
61
62 Inputs:
63 index -- Word16 -- received pitch index
64 pit_min -- Word16 -- minimum pitch lag
65 pit_max -- Word16 -- maximum pitch lag
66 i_subfr -- Word16 -- subframe flag
67 T0 -- Pointer to type Word16 -- integer part of pitch lag
68
69 Outputs:
70
71 T0 -- Pointer to type Word16 -- integer part of pitch lag
72 T0_frac -- Pointer to type Word16 -- fractional part of pitch lag
73 pOverflow -- Pointer to type Flag -- Flag set when overflow occurs
74
75 Returns:
76 None.
77
78 Global Variables Used:
79 None
80
81 Local Variables Needed:
82 None
83
84 ------------------------------------------------------------------------------
85 FUNCTION DESCRIPTION
86
87 PURPOSE: Decoding of fractional pitch lag with 1/6 resolution.
88 Extract the integer and fraction parts of the pitch lag from
89 the received adaptive codebook index.
90
91 See "Enc_lag6.c" for more details about the encoding procedure.
92
93 The fractional lag in 1st and 3rd subframes is encoded with 9 bits
94 while that in 2nd and 4th subframes is relatively encoded with 6 bits.
95 Note that in relative encoding only 61 values are used. If the
96 decoder receives 61, 62, or 63 as the relative pitch index, it means
97 that a transmission error occurred. In this case, the pitch lag from
98 previous subframe (actually from previous frame) is used.
99
100 ------------------------------------------------------------------------------
101 REQUIREMENTS
102
103
104
105 ------------------------------------------------------------------------------
106 REFERENCES
107
108 dec_lag6.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
109
110 ------------------------------------------------------------------------------
111 PSEUDO-CODE
112
113
114
115 ------------------------------------------------------------------------------
116 RESOURCES USED
117 When the code is written for a specific target processor the
118 the resources used should be documented below.
119
120 STACK USAGE: [stack count for this module] + [variable to represent
121 stack usage for each subroutine called]
122
123 where: [stack usage variable] = stack usage for [subroutine
124 name] (see [filename].ext)
125
126 DATA MEMORY USED: x words
127
128 PROGRAM MEMORY USED: x words
129
130 CLOCK CYCLES: [cycle count equation for this module] + [variable
131 used to represent cycle count for each subroutine
132 called]
133
134 where: [cycle count variable] = cycle count for [subroutine
135 name] (see [filename].ext)
136
137 ------------------------------------------------------------------------------
138 */
139
140
141 /*----------------------------------------------------------------------------
142 ; INCLUDES
143 ----------------------------------------------------------------------------*/
144 #include "dec_lag6.h"
145 #include "typedef.h"
146 #include "basic_op.h"
147
148 /*----------------------------------------------------------------------------
149 ; MACROS
150 ; Define module specific macros here
151 ----------------------------------------------------------------------------*/
152
153
154 /*----------------------------------------------------------------------------
155 ; DEFINES
156 ; Include all pre-processor statements here. Include conditional
157 ; compile variables also.
158 ----------------------------------------------------------------------------*/
159
160 /*----------------------------------------------------------------------------
161 ; LOCAL FUNCTION DEFINITIONS
162 ; Function Prototype declaration
163 ----------------------------------------------------------------------------*/
164
165
166 /*----------------------------------------------------------------------------
167 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS
168 ; Variable declaration - defined here and used outside this module
169 ----------------------------------------------------------------------------*/
170
171 /*----------------------------------------------------------------------------
172 ; EXTERNAL FUNCTION REFERENCES
173 ; Declare functions defined elsewhere and referenced in this module
174 ----------------------------------------------------------------------------*/
175
176 /*----------------------------------------------------------------------------
177 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
178 ; Declare variables used in this module but defined elsewhere
179 ----------------------------------------------------------------------------*/
180
181 /*----------------------------------------------------------------------------
182 ; FUNCTION CODE
183 ----------------------------------------------------------------------------*/
184
Dec_lag6(Word16 index,Word16 pit_min,Word16 pit_max,Word16 i_subfr,Word16 * T0,Word16 * T0_frac,Flag * pOverflow)185 void Dec_lag6(
186 Word16 index, /* input : received pitch index */
187 Word16 pit_min, /* input : minimum pitch lag */
188 Word16 pit_max, /* input : maximum pitch lag */
189 Word16 i_subfr, /* input : subframe flag */
190 Word16 *T0, /* in/out: integer part of pitch lag */
191 Word16 *T0_frac, /* output: fractional part of pitch lag */
192 Flag *pOverflow /* o : Flag set when overflow occurs */
193 )
194 {
195 Word16 i;
196 Word16 T0_min;
197 Word16 T0_max;
198 Word16 k;
199 Word16 w;
200
201 if (i_subfr == 0) /* if 1st or 3rd subframe */
202 {
203 if (index < 463)
204 {
205 /* T0 = (index+5)/6 + 17 */
206 i = index + 5;
207 i =
208 mult(
209 i,
210 5462,
211 pOverflow);
212
213 i =
214 add(
215 i,
216 17,
217 pOverflow);
218
219 *T0 = i;
220
221 /* i = 3* (*T0) */
222
223 i = add(i, i, pOverflow);
224 i = add(i, *T0, pOverflow);
225
226 /* *T0_frac = index - T0*6 + 105 */
227
228 i =
229 add(
230 i,
231 i,
232 pOverflow);
233
234 i =
235 sub(
236 index,
237 i,
238 pOverflow);
239
240 *T0_frac =
241 add(
242 i,
243 105,
244 pOverflow);
245 }
246 else
247 {
248 *T0 =
249 sub(
250 index,
251 368,
252 pOverflow);
253
254 *T0_frac = 0;
255 }
256 }
257 else /* second or fourth subframe */
258 {
259 /* find T0_min and T0_max for 2nd (or 4th) subframe */
260
261 T0_min =
262 sub(
263 *T0,
264 5,
265 pOverflow);
266
267 if (T0_min < pit_min)
268 {
269 T0_min = pit_min;
270 }
271
272 T0_max =
273 add(
274 T0_min,
275 9,
276 pOverflow);
277
278 if (T0_max > pit_max)
279 {
280 T0_max = pit_max;
281
282 T0_min =
283 sub(
284 T0_max,
285 9,
286 pOverflow);
287 }
288
289 /* i = (index+5)/6 - 1 */
290 i =
291 add(
292 index,
293 5,
294 pOverflow);
295
296 i =
297 mult(
298 i,
299 5462,
300 pOverflow);
301
302 i =
303 sub(
304 i,
305 1,
306 pOverflow);
307
308 *T0 =
309 add(
310 i,
311 T0_min,
312 pOverflow);
313
314 /* i = 3* (*T0) */
315
316 w = add(i, i, pOverflow);
317 i = add(i, w, pOverflow);
318
319 i =
320 add(
321 i,
322 i,
323 pOverflow);
324
325 k =
326 sub(
327 index,
328 3,
329 pOverflow);
330
331 *T0_frac =
332 sub(
333 k,
334 i,
335 pOverflow);
336 }
337 }
338