1 /*____________________________________________________________________________
2
3 FreeAmp - The Free MP3 Player
4
5 MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology
6 Corp. http://www.xingtech.com
7
8 Portions Copyright (C) 1998-1999 EMusic.com
9
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2 of the License, or
13 (at your option) any later version.
14
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
19
20 You should have received a copy of the GNU General Public License
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23
24 $Id: iupL1.c,v 1.6 2000/10/13 14:29:02 ijr Exp $
25 ____________________________________________________________________________*/
26
27 /**** iupL1.c ***************************************************
28
29 MPEG audio decoder Layer I mpeg1 and mpeg2
30 should be portable ANSI C, should be endian independent
31
32 icupL1 integer version of cupL1.c
33
34 ******************************************************************/
35 /*======================================================================*/
36 /* Read Only */
37 static int bat_bit_masterL1[] =
38 {
39 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
40
41 /*======================================================================*/
unpack_baL1(MPEGI * m)42 static void unpack_baL1(MPEGI *m)
43 {
44 int k;
45 int nstereo;
46 int n;
47
48 m->iup.bit_skip = 0;
49 nstereo = m->iup.stereo_sb;
50 for (k = 0; k < m->iup.nbatL1; k++)
51 {
52 mac_load_check(4);
53 n = m->iup.ballo[k] = m->iup.samp_dispatch[k] = mac_load(4);
54 if (k >= m->iup.nsb_limit)
55 m->iup.bit_skip += bat_bit_masterL1[m->iup.samp_dispatch[k]];
56 m->iup.c_value[k] = m->iup.look_c_valueL1[n];
57 m->iup.c_shift[k] = m->iup.look_c_shiftL1[n];
58 if (--nstereo < 0)
59 {
60 m->iup.ballo[k + 1] = m->iup.ballo[k];
61 m->iup.samp_dispatch[k] += 15; /* flag as joint */
62 m->iup.samp_dispatch[k + 1] = m->iup.samp_dispatch[k]; /* flag for sf */
63 m->iup.c_value[k + 1] = m->iup.c_value[k];
64 m->iup.c_shift[k + 1] = m->iup.c_shift[k];
65 k++;
66 }
67 }
68 m->iup.samp_dispatch[m->iup.nsb_limit] = 31; /* terminate the dispatcher with skip */
69 m->iup.samp_dispatch[k] = 30; /* terminate the dispatcher */
70
71 }
72 /*-------------------------------------------------------------------------*/
unpack_sfL1(MPEGI * m)73 static void unpack_sfL1(MPEGI *m) /* unpack scale factor */
74 { /* combine dequant and scale factors */
75 int i, n;
76 INT32 tmp; /* only reason tmp is 32 bit is to get 32 bit mult result */
77
78 for (i = 0; i < m->iup.nbatL1; i++)
79 {
80 if (m->iup.ballo[i])
81 {
82 mac_load_check(6);
83 tmp = m->iup.c_value[i];
84 n = m->iup.c_shift[i];
85 m->iup.cs_factorL1[i] = (tmp * m->iup.sf_table[mac_load(6)]) >> n;
86 }
87 }
88
89 /*-- done --*/
90 }
91 /*-------------------------------------------------------------------------*/
92 #define UNPACKL1_N(n) s[k] = (m->iup.cs_factorL1[k]*(load(m,n)-((1 << (n-1)) -1)))>>(n-1); \
93 goto dispatch;
94 #define UNPACKL1J_N(n) tmp = (load(m,n)-((1 << (n-1)) -1)); \
95 s[k] = (m->iup.cs_factorL1[k]*tmp)>>(n-1); \
96 s[k+1] = (m->iup.cs_factorL1[k+1]*tmp)>>(n-1); \
97 k++; /* skip right chan dispatch */ \
98 goto dispatch;
99 /*-------------------------------------------------------------------------*/
unpack_sampL1(MPEGI * m)100 static void unpack_sampL1(MPEGI *m) /* unpack samples */
101 {
102 int j, k;
103 SAMPLEINT *s;
104 INT32 tmp;
105
106 s = m->iup.sample;
107 for (j = 0; j < 12; j++)
108 {
109 k = -1;
110 dispatch:switch (m->iup.samp_dispatch[++k])
111 {
112 case 0:
113 s[k] = 0;
114 goto dispatch;
115 case 1:
116 UNPACKL1_N(2) /* 3 levels */
117 case 2:
118 UNPACKL1_N(3) /* 7 levels */
119 case 3:
120 UNPACKL1_N(4) /* 15 levels */
121 case 4:
122 UNPACKL1_N(5) /* 31 levels */
123 case 5:
124 UNPACKL1_N(6) /* 63 levels */
125 case 6:
126 UNPACKL1_N(7) /* 127 levels */
127 case 7:
128 UNPACKL1_N(8) /* 255 levels */
129 case 8:
130 UNPACKL1_N(9) /* 511 levels */
131 case 9:
132 UNPACKL1_N(10) /* 1023 levels */
133 case 10:
134 UNPACKL1_N(11) /* 2047 levels */
135 case 11:
136 UNPACKL1_N(12) /* 4095 levels */
137 case 12:
138 UNPACKL1_N(13) /* 8191 levels */
139 case 13:
140 UNPACKL1_N(14) /* 16383 levels */
141 case 14:
142 UNPACKL1_N(15) /* 32767 levels */
143 /* -- joint ---- */
144 case 15 + 0:
145 s[k + 1] = s[k] = 0;
146 k++; /* skip right chan dispatch */
147 goto dispatch;
148 /* -- joint ---- */
149 case 15 + 1:
150 UNPACKL1J_N(2) /* 3 levels */
151 case 15 + 2:
152 UNPACKL1J_N(3) /* 7 levels */
153 case 15 + 3:
154 UNPACKL1J_N(4) /* 15 levels */
155 case 15 + 4:
156 UNPACKL1J_N(5) /* 31 levels */
157 case 15 + 5:
158 UNPACKL1J_N(6) /* 63 levels */
159 case 15 + 6:
160 UNPACKL1J_N(7) /* 127 levels */
161 case 15 + 7:
162 UNPACKL1J_N(8) /* 255 levels */
163 case 15 + 8:
164 UNPACKL1J_N(9) /* 511 levels */
165 case 15 + 9:
166 UNPACKL1J_N(10) /* 1023 levels */
167 case 15 + 10:
168 UNPACKL1J_N(11) /* 2047 levels */
169 case 15 + 11:
170 UNPACKL1J_N(12) /* 4095 levels */
171 case 15 + 12:
172 UNPACKL1J_N(13) /* 8191 levels */
173 case 15 + 13:
174 UNPACKL1J_N(14) /* 16383 levels */
175 case 15 + 14:
176 UNPACKL1J_N(15) /* 32767 levels */
177
178 /* -- end of dispatch -- */
179 case 31:
180 skip(m, m->iup.bit_skip);
181 case 30:
182 s += 64;
183 } /* end switch */
184 } /* end j loop */
185
186 /*-- done --*/
187 }
188 /*-------------------------------------------------------------------------*/
unpackL1(MPEGI * m)189 static void unpackL1(MPEGI *m)
190 {
191 int prot;
192
193 /* at entry bit getter points at id, sync skipped by caller */
194
195 load(m,3); /* skip id and option (checked by init) */
196 prot = load(m,1); /* load prot bit */
197 load(m,6); /* skip to pad */
198 m->iup.pad = load(m,1) << 2;
199 load(m,1); /* skip to mode */
200 m->iup.stereo_sb = look_joint[load(m,4)];
201 if (prot)
202 load(m,4); /* skip to data */
203 else
204 load(m,20); /* skip crc */
205
206 unpack_baL1(m); /* unpack bit allocation */
207 unpack_sfL1(m); /* unpack scale factor */
208 unpack_sampL1(m); /* unpack samples */
209
210
211 }
212 /*-------------------------------------------------------------------------*/
213
214 #ifdef _MSC_VER
215 #pragma warning(disable: 4056)
216 #endif
217
i_audio_decode_initL1(MPEGI * m,MPEG_HEAD * h,int framebytes_arg,int reduction_code,int transform_code,int convert_code,int freq_limit)218 int i_audio_decode_initL1(MPEGI *m, MPEG_HEAD * h, int framebytes_arg,
219 int reduction_code, int transform_code, int convert_code,
220 int freq_limit)
221 {
222 int i, k;
223 long samprate;
224 int limit;
225 int stepbit;
226 long step;
227 int bit_code;
228
229 /*--- sf table built by Layer II init ---*/
230
231 if (m->iup.first_pass_L1)
232 {
233 stepbit = 2;
234 step = 4;
235 for (i = 1; i < 16; i++)
236 {
237 m->iup.look_c_valueL1[i] = (int) (32768.0 * 2.0 / (step - 1));
238 m->iup.look_c_shiftL1[i] = 16 - stepbit;
239 stepbit++;
240 step <<= 1;
241 }
242 m->iup.first_pass_L1 = 0;
243 }
244
245 m->iup.unpack_routine = unpackL1;
246
247
248 transform_code = transform_code; /* not used, asm compatability */
249 bit_code = 0;
250 if (convert_code & 8)
251 bit_code = 1;
252 convert_code = convert_code & 3; /* higher bits used by dec8 freq cvt */
253 if (reduction_code < 0)
254 reduction_code = 0;
255 if (reduction_code > 2)
256 reduction_code = 2;
257 if (freq_limit < 1000)
258 freq_limit = 1000;
259
260
261 m->iup.framebytes = framebytes_arg;
262 /* check if code handles */
263 if (h->option != 3)
264 return 0; /* layer I only */
265
266 m->iup.nbatL1 = 32;
267 m->iup.max_sb = m->iup.nbatL1;
268 /*----- compute nsb_limit --------*/
269 samprate = sr_table[4 * h->id + h->sr_index];
270 m->iup.nsb_limit = (freq_limit * 64L + samprate / 2) / samprate;
271 /*- caller limit -*/
272 /*---- limit = 0.94*(32>>reduction_code); ----*/
273 limit = (32 >> reduction_code);
274 if (limit > 8)
275 limit--;
276 if (m->iup.nsb_limit > limit)
277 m->iup.nsb_limit = limit;
278 if (m->iup.nsb_limit > m->iup.max_sb)
279 m->iup.nsb_limit = m->iup.max_sb;
280
281 m->iup.outvalues = 384 >> reduction_code;
282 if (h->mode != 3)
283 { /* adjust for 2 channel modes */
284 m->iup.nbatL1 *= 2;
285 m->iup.max_sb *= 2;
286 m->iup.nsb_limit *= 2;
287 }
288
289 /* set sbt function */
290 m->iup.nsbt = 12;
291 k = 1 + convert_code;
292 if (h->mode == 3)
293 {
294 k = 0;
295 }
296 m->iup.sbt = sbt_table[bit_code][reduction_code][k];
297 m->iup.outvalues *= out_chans[k];
298 if (bit_code != 0)
299 m->iup.outbytes = m->iup.outvalues;
300 else
301 m->iup.outbytes = sizeof(short) * m->iup.outvalues;
302
303 m->iup.decinfo.channels = out_chans[k];
304 m->iup.decinfo.outvalues = m->iup.outvalues;
305 m->iup.decinfo.samprate = samprate >> reduction_code;
306 if (bit_code != 0)
307 m->iup.decinfo.bits = 8;
308 else
309 m->iup.decinfo.bits = sizeof(short) * 8;
310
311 m->iup.decinfo.framebytes = m->iup.framebytes;
312 m->iup.decinfo.type = 0;
313
314
315 /* clear sample buffer, unused sub bands must be 0 */
316 for (i = 0; i < 768; i++)
317 m->iup.sample[i] = 0;
318
319
320 /* init sub-band transform */
321 i_sbt_init();
322
323 return 1;
324 }
325
326 #ifdef _MSC_VER
327 #pragma warning(default: 4056)
328 #endif
329
330 /*---------------------------------------------------------*/
331