1 /*
2  * Mpeg Layer-2 audio decoder
3  * --------------------------
4  * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
5  *
6  */
7 
8 /* $Id: layer2.c,v 1.1 2002/03/29 19:14:40 snelg Exp $ */
9 
10 #ifdef HAVE_CONFIG_H
11 # include <config.h>
12 #endif
13 
14 #ifdef USE_LAYER_2
15 
16 
17 #include "common.h"
18 #include "layer2.h"
19 #include "l2tables.h"
20 #include "decode_i386.h"
21 
22 #ifdef WITH_DMALLOC
23 #include <dmalloc.h>
24 #endif
25 
26 static int grp_3tab[32 * 3] = { 0, };   /* used: 27 */
27 static int grp_5tab[128 * 3] = { 0, };  /* used: 125 */
28 static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */
29 
init_layer2(void)30 void init_layer2(void)
31 {
32   static const double mulmul[27] = {
33     0.0 , -2.0/3.0 , 2.0/3.0 ,
34     2.0/7.0 , 2.0/15.0 , 2.0/31.0, 2.0/63.0 , 2.0/127.0 , 2.0/255.0 ,
35     2.0/511.0 , 2.0/1023.0 , 2.0/2047.0 , 2.0/4095.0 , 2.0/8191.0 ,
36     2.0/16383.0 , 2.0/32767.0 , 2.0/65535.0 ,
37     -4.0/5.0 , -2.0/5.0 , 2.0/5.0, 4.0/5.0 ,
38     -8.0/9.0 , -4.0/9.0 , -2.0/9.0 , 2.0/9.0 , 4.0/9.0 , 8.0/9.0 };
39   static const int base[3][9] = {
40      { 1 , 0, 2 , } ,
41      { 17, 18, 0 , 19, 20 , } ,
42      { 21, 1, 22, 23, 0, 24, 25, 2, 26 } };
43   int i,j,k,l,len;
44   real *table;
45   static const int tablen[3] = { 3 , 5 , 9 };
46   static int *itable,*tables[3] = { grp_3tab , grp_5tab , grp_9tab };
47 
48   for(i=0;i<3;i++)
49   {
50     itable = tables[i];
51     len = tablen[i];
52     for(j=0;j<len;j++)
53       for(k=0;k<len;k++)
54         for(l=0;l<len;l++)
55         {
56           *itable++ = base[i][l];
57           *itable++ = base[i][k];
58           *itable++ = base[i][j];
59         }
60   }
61 
62   for(k=0;k<27;k++)
63   {
64     double m=mulmul[k];
65     table = muls[k];
66     for(j=3,i=0;i<63;i++,j--)
67       *table++ = (real)(m * pow(2.0,(double) j / 3.0));
68     *table++ = 0.0;
69   }
70 }
71 
72 
II_step_one(unsigned int * bit_alloc,int * scale,struct frame * fr)73 void II_step_one(unsigned int *bit_alloc,int *scale,struct frame *fr)
74 {
75     int stereo = fr->stereo-1;
76     int sblimit = fr->II_sblimit;
77     int jsbound = fr->jsbound;
78     int sblimit2 = fr->II_sblimit<<stereo;
79     struct al_table2 *alloc1 = fr->alloc;
80     int i;
81     static unsigned int scfsi_buf[64];
82     unsigned int *scfsi,*bita;
83     int sc,step;
84 
85     bita = bit_alloc;
86     if(stereo)
87     {
88       for (i=jsbound;i;i--,alloc1+=(1<<step))
89       {
90         *bita++ = (char) getbits(step=alloc1->bits);
91         *bita++ = (char) getbits(step);
92       }
93       for (i=sblimit-jsbound;i;i--,alloc1+=(1<<step))
94       {
95         bita[0] = (char) getbits(step=alloc1->bits);
96         bita[1] = bita[0];
97         bita+=2;
98       }
99       bita = bit_alloc;
100       scfsi=scfsi_buf;
101       for (i=sblimit2;i;i--)
102         if (*bita++)
103           *scfsi++ = (char) getbits_fast(2);
104     }
105     else /* mono */
106     {
107       for (i=sblimit;i;i--,alloc1+=(1<<step))
108         *bita++ = (char) getbits(step=alloc1->bits);
109       bita = bit_alloc;
110       scfsi=scfsi_buf;
111       for (i=sblimit;i;i--)
112         if (*bita++)
113           *scfsi++ = (char) getbits_fast(2);
114     }
115 
116     bita = bit_alloc;
117     scfsi=scfsi_buf;
118     for (i=sblimit2;i;i--)
119       if (*bita++)
120         switch (*scfsi++)
121         {
122           case 0:
123                 *scale++ = getbits_fast(6);
124                 *scale++ = getbits_fast(6);
125                 *scale++ = getbits_fast(6);
126                 break;
127           case 1 :
128                 *scale++ = sc = getbits_fast(6);
129                 *scale++ = sc;
130                 *scale++ = getbits_fast(6);
131                 break;
132           case 2:
133                 *scale++ = sc = getbits_fast(6);
134                 *scale++ = sc;
135                 *scale++ = sc;
136                 break;
137           default:              /* case 3 */
138                 *scale++ = getbits_fast(6);
139                 *scale++ = sc = getbits_fast(6);
140                 *scale++ = sc;
141                 break;
142         }
143 
144 }
145 
II_step_two(unsigned int * bit_alloc,real fraction[2][4][SBLIMIT],int * scale,struct frame * fr,int x1)146 void II_step_two(unsigned int *bit_alloc,real fraction[2][4][SBLIMIT],int *scale,struct frame *fr,int x1)
147 {
148     int i,j,k,ba;
149     int stereo = fr->stereo;
150     int sblimit = fr->II_sblimit;
151     int jsbound = fr->jsbound;
152     struct al_table2 *alloc2,*alloc1 = fr->alloc;
153     unsigned int *bita=bit_alloc;
154     int d1,step;
155 
156     for (i=0;i<jsbound;i++,alloc1+=(1<<step))
157     {
158       step = alloc1->bits;
159       for (j=0;j<stereo;j++)
160       {
161         if ( (ba=*bita++) )
162         {
163           k=(alloc2 = alloc1+ba)->bits;
164           if( (d1=alloc2->d) < 0)
165           {
166             real cm=muls[k][scale[x1]];
167             fraction[j][0][i] = ((real) ((int)getbits(k) + d1)) * cm;
168             fraction[j][1][i] = ((real) ((int)getbits(k) + d1)) * cm;
169             fraction[j][2][i] = ((real) ((int)getbits(k) + d1)) * cm;
170           }
171           else
172           {
173             static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
174             unsigned int idx,*tab,m=scale[x1];
175             idx = (unsigned int) getbits(k);
176             tab = (unsigned int *) (table[d1] + idx + idx + idx);
177             fraction[j][0][i] = muls[*tab++][m];
178             fraction[j][1][i] = muls[*tab++][m];
179             fraction[j][2][i] = muls[*tab][m];
180           }
181           scale+=3;
182         }
183         else
184           fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
185       }
186     }
187 
188     for (i=jsbound;i<sblimit;i++,alloc1+=(1<<step))
189     {
190       step = alloc1->bits;
191       bita++;	/* channel 1 and channel 2 bitalloc are the same */
192       if ( (ba=*bita++) )
193       {
194         k=(alloc2 = alloc1+ba)->bits;
195         if( (d1=alloc2->d) < 0)
196         {
197           real cm;
198           cm=muls[k][scale[x1+3]];
199           fraction[1][0][i] = (fraction[0][0][i] = (real) ((int)getbits(k) + d1) ) * cm;
200           fraction[1][1][i] = (fraction[0][1][i] = (real) ((int)getbits(k) + d1) ) * cm;
201           fraction[1][2][i] = (fraction[0][2][i] = (real) ((int)getbits(k) + d1) ) * cm;
202           cm=muls[k][scale[x1]];
203           fraction[0][0][i] *= cm; fraction[0][1][i] *= cm; fraction[0][2][i] *= cm;
204         }
205         else
206         {
207           static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
208           unsigned int idx,*tab,m1,m2;
209           m1 = scale[x1]; m2 = scale[x1+3];
210           idx = (unsigned int) getbits(k);
211           tab = (unsigned int *) (table[d1] + idx + idx + idx);
212           fraction[0][0][i] = muls[*tab][m1]; fraction[1][0][i] = muls[*tab++][m2];
213           fraction[0][1][i] = muls[*tab][m1]; fraction[1][1][i] = muls[*tab++][m2];
214           fraction[0][2][i] = muls[*tab][m1]; fraction[1][2][i] = muls[*tab][m2];
215         }
216         scale+=6;
217       }
218       else {
219         fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] =
220         fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;
221       }
222 /*
223    should we use individual scalefac for channel 2 or
224    is the current way the right one , where we just copy channel 1 to
225    channel 2 ??
226    The current 'strange' thing is, that we throw away the scalefac
227    values for the second channel ...!!
228 -> changed .. now we use the scalefac values of channel one !!
229 */
230     }
231 
232 //  if(sblimit > (fr->down_sample_sblimit) )
233 //    sblimit = fr->down_sample_sblimit;
234 
235   for(i=sblimit;i<SBLIMIT;i++)
236     for (j=0;j<stereo;j++)
237       fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
238 
239 }
240 
II_select_table(struct frame * fr)241 static void II_select_table(struct frame *fr)
242 {
243   static const int translate[3][2][16] =
244    { { { 0,2,2,2,2,2,2,0,0,0,1,1,1,1,1,0 } ,
245        { 0,2,2,0,0,0,1,1,1,1,1,1,1,1,1,0 } } ,
246      { { 0,2,2,2,2,2,2,0,0,0,0,0,0,0,0,0 } ,
247        { 0,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0 } } ,
248      { { 0,3,3,3,3,3,3,0,0,0,1,1,1,1,1,0 } ,
249        { 0,3,3,0,0,0,1,1,1,1,1,1,1,1,1,0 } } };
250 
251   int table,sblim;
252   static const struct al_table2 *tables[5] =
253        { alloc_0, alloc_1, alloc_2, alloc_3 , alloc_4 };
254   static const int sblims[5] = { 27 , 30 , 8, 12 , 30 };
255 
256   if(fr->lsf)
257     table = 4;
258   else
259     table = translate[fr->sampling_frequency][2-fr->stereo][fr->bitrate_index];
260   sblim = sblims[table];
261 
262   fr->alloc      = (struct al_table2*)tables[table];
263   fr->II_sblimit = sblim;
264 }
265 
266 
do_layer2(PMPSTR mp,unsigned char * pcm_sample,int * pcm_point)267 int do_layer2( PMPSTR mp,unsigned char *pcm_sample,int *pcm_point)
268 //int do_layer2(struct frame *fr,int outmode,struct audio_info_struct *ai)
269 {
270   int clip=0;
271   int i,j;
272   real fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
273   unsigned int bit_alloc[64];
274   int scale[192];
275   struct frame *fr=&(mp->fr);
276   int stereo = fr->stereo;
277   int single = fr->single;
278 
279   II_select_table(fr);
280   fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ?
281      (fr->mode_ext<<2)+4 : fr->II_sblimit;
282 
283   if(stereo == 1 || single == 3)
284     single = 0;
285 
286   II_step_one(bit_alloc, scale, fr);
287 
288   for (i=0;i<SCALE_BLOCK;i++)
289   {
290     II_step_two(bit_alloc,fraction,scale,fr,i>>2);
291     for (j=0;j<3;j++)
292     {
293       if(single >= 0)
294       {
295         clip += synth_1to1_mono(mp, fraction[single][j],pcm_sample,pcm_point);
296       }
297       else {
298           int p1 = *pcm_point;
299           clip += synth_1to1(mp, fraction[0][j],0,pcm_sample,&p1);
300           clip += synth_1to1(mp, fraction[1][j],1,pcm_sample,pcm_point);
301       }
302     }
303   }
304 
305   return clip;
306 }
307 
308 
309 #endif
310