source: golgotha/src/i4/loaders/mp3/layer2.cc @ 80

Last change on this file since 80 was 80, checked in by Sam Hocevar, 12 years ago
  • Adding the Golgotha source code. Not sure what's going to be interesting in there, but since it's all public domain, there's certainly stuff to pick up.
File size: 8.5 KB
Line 
1/********************************************************************** <BR>
2  This file is part of Crack dot Com's free source code release of
3  Golgotha. <a href="http://www.crack.com/golgotha_release"> <BR> for
4  information about compiling & licensing issues visit this URL</a>
5  <PRE> If that doesn't help, contact Jonathan Clark at
6  golgotha_source@usa.net (Subject should have "GOLG" in it)
7***********************************************************************/
8
9/*
10 * Mpeg Layer-2 audio decoder
11 * --------------------------
12 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
13 *
14 */
15
16#include "loaders/mp3/mpg123.hh"
17
18static int grp_3tab[32 * 3] = { 0, };   /* used: 27 */
19static int grp_5tab[128 * 3] = { 0, };  /* used: 125 */
20static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */
21
22real muls[27][64];      /* also used by layer 1 */
23
24void init_layer2(void)
25{
26  static double mulmul[27] = {
27    0.0 , -2.0/3.0 , 2.0/3.0 ,
28    2.0/7.0 , 2.0/15.0 , 2.0/31.0, 2.0/63.0 , 2.0/127.0 , 2.0/255.0 ,
29    2.0/511.0 , 2.0/1023.0 , 2.0/2047.0 , 2.0/4095.0 , 2.0/8191.0 ,
30    2.0/16383.0 , 2.0/32767.0 , 2.0/65535.0 ,
31    -4.0/5.0 , -2.0/5.0 , 2.0/5.0, 4.0/5.0 ,
32    -8.0/9.0 , -4.0/9.0 , -2.0/9.0 , 2.0/9.0 , 4.0/9.0 , 8.0/9.0 };
33  static int base[3][9] = {
34     { 1 , 0, 2 , } ,
35     { 17, 18, 0 , 19, 20 , } ,
36     { 21, 1, 22, 23, 0, 24, 25, 2, 26 } };
37  int i,j,k,l,len;
38  real *table;
39  static int tablen[3] = { 3 , 5 , 9 };
40  static int *itable,*tables[3] = { grp_3tab , grp_5tab , grp_9tab };
41
42        memset(grp_3tab, 0, sizeof(grp_3tab));
43        memset(grp_5tab, 0, sizeof(grp_5tab));
44        memset(grp_9tab, 0, sizeof(grp_9tab));
45        memset(grp_9tab, 0, sizeof(grp_9tab));
46
47  for(i=0;i<3;i++)
48  {
49    itable = tables[i];
50    len = tablen[i];
51    for(j=0;j<len;j++)
52      for(k=0;k<len;k++)
53        for(l=0;l<len;l++)
54        {
55          *itable++ = base[i][l];
56          *itable++ = base[i][k];
57          *itable++ = base[i][j];
58        }
59  }
60
61  for(k=0;k<27;k++)
62  {
63    double m=mulmul[k];
64    table = muls[k];
65    for(j=3,i=0;i<63;i++,j--)
66      *table++ = m * pow(2.0,(double) j / 3.0);
67    *table++ = 0.0;
68  }
69}
70
71
72void II_step_one(unsigned int *bit_alloc,int *scale,struct frame *fr)
73{
74    int stereo = fr->stereo-1;
75    int sblimit = fr->II_sblimit;
76    int jsbound = fr->jsbound;
77    int sblimit2 = fr->II_sblimit<<stereo;
78    struct al_table *alloc1 = fr->alloc;
79    int i;
80    unsigned int *scfsi,*bita;
81    int sc,step;
82                static unsigned int scfsi_buf[64];
83
84    bita = bit_alloc;
85    if(stereo)
86    {
87      for (i=jsbound;i;i--,alloc1+=(1<<step))
88      {
89        *bita++ = (char) getbits(step=alloc1->bits);
90        *bita++ = (char) getbits(step);
91      }
92      for (i=sblimit-jsbound;i;i--,alloc1+=(1<<step))
93      {
94        bita[0] = (char) getbits(step=alloc1->bits);
95        bita[1] = bita[0];
96        bita+=2;
97      }
98      bita = bit_alloc;
99      scfsi=scfsi_buf;
100      for (i=sblimit2;i;i--)
101        if (*bita++)
102          *scfsi++ = (char) getbits_fast(2);
103    }
104    else /* mono */
105    {
106      for (i=sblimit;i;i--,alloc1+=(1<<step))
107        *bita++ = (char) getbits(step=alloc1->bits);
108      bita = bit_alloc;
109      scfsi=scfsi_buf;
110      for (i=sblimit;i;i--)
111        if (*bita++)
112          *scfsi++ = (char) getbits_fast(2);
113    }
114
115    bita = bit_alloc;
116    scfsi=scfsi_buf;
117    for (i=sblimit2;i;i--)
118      if (*bita++)
119        switch (*scfsi++)
120        {
121          case 0:
122                *scale++ = getbits_fast(6);
123                *scale++ = getbits_fast(6);
124                *scale++ = getbits_fast(6);
125                break;
126          case 1 :
127                *scale++ = sc = getbits_fast(6);
128                *scale++ = sc;
129                *scale++ = getbits_fast(6);
130                break;
131          case 2:
132                *scale++ = sc = getbits_fast(6);
133                *scale++ = sc;
134                *scale++ = sc;
135                break;
136          default:              /* case 3 */
137                *scale++ = getbits_fast(6);
138                *scale++ = sc = getbits_fast(6);
139                *scale++ = sc;
140                break;
141        }
142
143}
144
145void II_step_two(unsigned int *bit_alloc,real fraction[2][4][SBLIMIT],int *scale,struct frame *fr,int x1)
146{
147    int i,j,k,ba;
148    int stereo = fr->stereo;
149    int sblimit = fr->II_sblimit;
150    int jsbound = fr->jsbound;
151    struct al_table *alloc2,*alloc1 = fr->alloc;
152    unsigned int *bita=bit_alloc;
153    int d1,step;
154
155    for (i=0;i<jsbound;i++,alloc1+=(1<<step))
156    {
157      step = alloc1->bits;
158      for (j=0;j<stereo;j++)
159      {
160        if ( (ba=*bita++) )
161        {
162          k=(alloc2 = alloc1+ba)->bits;
163          if( (d1=alloc2->d) < 0)
164          {
165            real cm=muls[k][scale[x1]];
166            fraction[j][0][i] = ((real) ((int)getbits(k) + d1)) * cm;
167            fraction[j][1][i] = ((real) ((int)getbits(k) + d1)) * cm;
168            fraction[j][2][i] = ((real) ((int)getbits(k) + d1)) * cm;
169          }       
170          else
171          {
172            static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
173            unsigned int idx,*tab,m=scale[x1];
174            idx = (unsigned int) getbits(k);
175            tab = (unsigned int *) (table[d1] + idx + idx + idx);
176            fraction[j][0][i] = muls[*tab++][m];
177            fraction[j][1][i] = muls[*tab++][m];
178            fraction[j][2][i] = muls[*tab][m]; 
179          }
180          scale+=3;
181        }
182        else
183          fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
184      }
185    }
186
187    for (i=jsbound;i<sblimit;i++,alloc1+=(1<<step))
188    {
189      step = alloc1->bits;
190      bita++;   /* channel 1 and channel 2 bitalloc are the same */
191      if ( (ba=*bita++) )
192      {
193        k=(alloc2 = alloc1+ba)->bits;
194        if( (d1=alloc2->d) < 0)
195        {
196          real cm;
197          cm=muls[k][scale[x1+3]];
198          fraction[1][0][i] = (fraction[0][0][i] = (real) ((int)getbits(k) + d1) ) * cm;
199          fraction[1][1][i] = (fraction[0][1][i] = (real) ((int)getbits(k) + d1) ) * cm;
200          fraction[1][2][i] = (fraction[0][2][i] = (real) ((int)getbits(k) + d1) ) * cm;
201          cm=muls[k][scale[x1]];
202          fraction[0][0][i] *= cm; fraction[0][1][i] *= cm; fraction[0][2][i] *= cm;
203        }
204        else
205        {
206          static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
207          unsigned int idx,*tab,m1,m2;
208          m1 = scale[x1]; m2 = scale[x1+3];
209          idx = (unsigned int) getbits(k);
210          tab = (unsigned int *) (table[d1] + idx + idx + idx);
211          fraction[0][0][i] = muls[*tab][m1]; fraction[1][0][i] = muls[*tab++][m2];
212          fraction[0][1][i] = muls[*tab][m1]; fraction[1][1][i] = muls[*tab++][m2];
213          fraction[0][2][i] = muls[*tab][m1]; fraction[1][2][i] = muls[*tab][m2];
214        }
215        scale+=6;
216      }
217      else {
218        fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] =
219        fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;
220      }
221/*
222   should we use individual scalefac for channel 2 or
223   is the current way the right one , where we just copy channel 1 to
224   channel 2 ??
225   The current 'strange' thing is, that we throw away the scalefac
226   values for the second channel ...!!
227-> changed .. now we use the scalefac values of channel one !!
228*/
229    }
230
231    if(sblimit > (SBLIMIT>>fr->down_sample) )
232      sblimit = SBLIMIT>>fr->down_sample;
233
234    for(i=sblimit;i<SBLIMIT;i++)
235      for (j=0;j<stereo;j++)
236        fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
237
238}
239
240int do_layer2(struct frame *fr,int outmode,struct audio_info_struct *ai)
241{
242  int clip=0;
243  int i,j;
244  int stereo = fr->stereo;
245  real fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
246  unsigned int bit_alloc[64];
247  int scale[192];
248  int single = fr->single;
249
250  if(stereo == 1 || single == 3)
251    single = 0;
252
253  II_step_one(bit_alloc, scale, fr);
254
255  for (i=0;i<SCALE_BLOCK;i++)
256  {
257    II_step_two(bit_alloc,fraction,scale,fr,i>>2);
258    for (j=0;j<3;j++)
259    {
260      if(single >= 0)
261      {
262        clip += (fr->synth_mono) (fraction[single][j],pcm_sample+pcm_point);
263      }
264      else {
265          clip += (fr->synth) (fraction[0][j],0,pcm_sample+pcm_point);
266          clip += (fr->synth) (fraction[1][j],1,pcm_sample+pcm_point);
267      }
268      pcm_point += fr->block_size;
269
270      if(pcm_point == audiobufsize)
271        audio_flush(outmode,ai);
272    }
273  }
274
275  return clip;
276}
277
278
Note: See TracBrowser for help on using the repository browser.