cup.c

FreeAMP(MP3播放)程序源代码-用来研究MP3解码

   int i;

   i = -1;
 dispatch:switch (m->cup.sf_dispatch[++i])
   {
      case 0:			/* 3 factors 012 */
	 mac_load_check(18);
	 m->cup.cs_factor[0][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 m->cup.cs_factor[1][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 m->cup.cs_factor[2][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 goto dispatch;
      case 1:			/* 2 factors 002 */
	 mac_load_check(12);
	 m->cup.cs_factor[1][i] = m->cup.cs_factor[0][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 m->cup.cs_factor[2][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 goto dispatch;
      case 2:			/* 1 factor 000 */
	 mac_load_check(6);
	 m->cup.cs_factor[2][i] = m->cup.cs_factor[1][i] = m->cup.cs_factor[0][i] =
	    m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 goto dispatch;
      case 3:			/* 2 factors 022 */
	 mac_load_check(12);
	 m->cup.cs_factor[0][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 m->cup.cs_factor[2][i] = m->cup.cs_factor[1][i] = m->cup.c_value[i] * m->cup.sf_table[mac_load(6)];
	 goto dispatch;
      case 4:			/* no allo */
/*-- m->cup.cs_factor[2][i] = m->cup.cs_factor[1][i] = m->cup.cs_factor[0][i] = 0.0;  --*/
	 goto dispatch;
      case 5:			/* all done */
	 ;
   }				/* end switch */
}
/*-------------------------------------------------------------------------*/
#define UNPACK_N(n) s[k]     =  m->cup.cs_factor[i][k]*(load(m,n)-((1 << (n-1)) -1));   \
    s[k+64]  =  m->cup.cs_factor[i][k]*(load(m,n)-((1 << (n-1)) -1));   \
    s[k+128] =  m->cup.cs_factor[i][k]*(load(m,n)-((1 << (n-1)) -1));   \
    goto dispatch;
#define UNPACK_N2(n) mac_load_check(3*n);                                         \
    s[k]     =  m->cup.cs_factor[i][k]*(mac_load(n)-((1 << (n-1)) -1));   \
    s[k+64]  =  m->cup.cs_factor[i][k]*(mac_load(n)-((1 << (n-1)) -1));   \
    s[k+128] =  m->cup.cs_factor[i][k]*(mac_load(n)-((1 << (n-1)) -1));   \
    goto dispatch;
#define UNPACK_N3(n) mac_load_check(2*n);                                         \
    s[k]     =  m->cup.cs_factor[i][k]*(mac_load(n)-((1 << (n-1)) -1));   \
    s[k+64]  =  m->cup.cs_factor[i][k]*(mac_load(n)-((1 << (n-1)) -1));   \
    mac_load_check(n);                                           \
    s[k+128] =  m->cup.cs_factor[i][k]*(mac_load(n)-((1 << (n-1)) -1));   \
    goto dispatch;
#define UNPACKJ_N(n) tmp        =  (load(m,n)-((1 << (n-1)) -1));                \
    s[k]       =  m->cup.cs_factor[i][k]*tmp;                       \
    s[k+1]     =  m->cup.cs_factor[i][k+1]*tmp;                     \
    tmp        =  (load(m,n)-((1 << (n-1)) -1));                 \
    s[k+64]    =  m->cup.cs_factor[i][k]*tmp;                       \
    s[k+64+1]  =  m->cup.cs_factor[i][k+1]*tmp;                     \
    tmp        =  (load(m,n)-((1 << (n-1)) -1));                 \
    s[k+128]   =  m->cup.cs_factor[i][k]*tmp;                       \
    s[k+128+1] =  m->cup.cs_factor[i][k+1]*tmp;                     \
    k++;       /* skip right chan dispatch */                \
    goto dispatch;
/*-------------------------------------------------------------------------*/
static void unpack_samp(MPEG *m)	/* unpack samples */
{
   int i, j, k;
   float *s;
   int n;
   long tmp;

   s = m->cup.sample;
   for (i = 0; i < 3; i++)
   {				/* 3 groups of scale factors */
      for (j = 0; j < 4; j++)
      {
	 k = -1;
       dispatch:switch (m->cup.samp_dispatch[++k])
	 {
	    case 0:
	       s[k + 128] = s[k + 64] = s[k] = 0.0F;
	       goto dispatch;
	    case 1:		/* 3 levels grouped 5 bits */
	       mac_load_check(5);
	       n = mac_load(5);
	       s[k] = m->cup.cs_factor[i][k] * m->cup.group3_table[n][0];
	       s[k + 64] = m->cup.cs_factor[i][k] * m->cup.group3_table[n][1];
	       s[k + 128] = m->cup.cs_factor[i][k] * m->cup.group3_table[n][2];
	       goto dispatch;
	    case 2:		/* 5 levels grouped 7 bits */
	       mac_load_check(7);
	       n = mac_load(7);
	       s[k] = m->cup.cs_factor[i][k] * m->cup.group5_table[n][0];
	       s[k + 64] = m->cup.cs_factor[i][k] * m->cup.group5_table[n][1];
	       s[k + 128] = m->cup.cs_factor[i][k] * m->cup.group5_table[n][2];
	       goto dispatch;
	    case 3:
	       UNPACK_N2(3)	/* 7 levels */
	    case 4:		/* 9 levels grouped 10 bits */
	       mac_load_check(10);
	       n = mac_load(10);
	       s[k] = m->cup.cs_factor[i][k] * m->cup.group9_table[n][0];
	       s[k + 64] = m->cup.cs_factor[i][k] * m->cup.group9_table[n][1];
	       s[k + 128] = m->cup.cs_factor[i][k] * m->cup.group9_table[n][2];
	       goto dispatch;
	    case 5:
	       UNPACK_N2(4)	/* 15 levels */
	    case 6:
	       UNPACK_N2(5)	/* 31 levels */
	    case 7:
	       UNPACK_N2(6)	/* 63 levels */
	    case 8:
	       UNPACK_N2(7)	/* 127 levels */
	    case 9:
	       UNPACK_N2(8)	/* 255 levels */
	    case 10:
	       UNPACK_N3(9)	/* 511 levels */
	    case 11:
	       UNPACK_N3(10)	/* 1023 levels */
	    case 12:
	       UNPACK_N3(11)	/* 2047 levels */
	    case 13:
	       UNPACK_N3(12)	/* 4095 levels */
	    case 14:
	       UNPACK_N(13)	/* 8191 levels */
	    case 15:
	       UNPACK_N(14)	/* 16383 levels */
	    case 16:
	       UNPACK_N(15)	/* 32767 levels */
	    case 17:
	       UNPACK_N(16)	/* 65535 levels */
/* -- joint ---- */
	    case 18 + 0:
	       s[k + 128 + 1] = s[k + 128] = s[k + 64 + 1] = s[k + 64] = s[k + 1] = s[k] = 0.0F;
	       k++;		/* skip right chan dispatch */
	       goto dispatch;
	    case 18 + 1:	/* 3 levels grouped 5 bits */
	       n = load(m,5);
	       s[k] = m->cup.cs_factor[i][k] * m->cup.group3_table[n][0];
	       s[k + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group3_table[n][0];
	       s[k + 64] = m->cup.cs_factor[i][k] * m->cup.group3_table[n][1];
	       s[k + 64 + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group3_table[n][1];
	       s[k + 128] = m->cup.cs_factor[i][k] * m->cup.group3_table[n][2];
	       s[k + 128 + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group3_table[n][2];
	       k++;		/* skip right chan dispatch */
	       goto dispatch;
	    case 18 + 2:	/* 5 levels grouped 7 bits */
	       n = load(m,7);
	       s[k] = m->cup.cs_factor[i][k] * m->cup.group5_table[n][0];
	       s[k + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group5_table[n][0];
	       s[k + 64] = m->cup.cs_factor[i][k] * m->cup.group5_table[n][1];
	       s[k + 64 + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group5_table[n][1];
	       s[k + 128] = m->cup.cs_factor[i][k] * m->cup.group5_table[n][2];
	       s[k + 128 + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group5_table[n][2];
	       k++;		/* skip right chan dispatch */
	       goto dispatch;
	    case 18 + 3:
	       UNPACKJ_N(3)	/* 7 levels */
	    case 18 + 4:	/* 9 levels grouped 10 bits */
	       n = load(m,10);
	       s[k] = m->cup.cs_factor[i][k] * m->cup.group9_table[n][0];
	       s[k + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group9_table[n][0];
	       s[k + 64] = m->cup.cs_factor[i][k] * m->cup.group9_table[n][1];
	       s[k + 64 + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group9_table[n][1];
	       s[k + 128] = m->cup.cs_factor[i][k] * m->cup.group9_table[n][2];
	       s[k + 128 + 1] = m->cup.cs_factor[i][k + 1] * m->cup.group9_table[n][2];
	       k++;		/* skip right chan dispatch */
	       goto dispatch;
	    case 18 + 5:
	       UNPACKJ_N(4)	/* 15 levels */
	    case 18 + 6:
	       UNPACKJ_N(5)	/* 31 levels */
	    case 18 + 7:
	       UNPACKJ_N(6)	/* 63 levels */
	    case 18 + 8:
	       UNPACKJ_N(7)	/* 127 levels */
	    case 18 + 9:
	       UNPACKJ_N(8)	/* 255 levels */
	    case 18 + 10:
	       UNPACKJ_N(9)	/* 511 levels */
	    case 18 + 11:
	       UNPACKJ_N(10)	/* 1023 levels */
	    case 18 + 12:
	       UNPACKJ_N(11)	/* 2047 levels */
	    case 18 + 13:
	       UNPACKJ_N(12)	/* 4095 levels */
	    case 18 + 14:
	       UNPACKJ_N(13)	/* 8191 levels */
	    case 18 + 15:
	       UNPACKJ_N(14)	/* 16383 levels */
	    case 18 + 16:
	       UNPACKJ_N(15)	/* 32767 levels */
	    case 18 + 17:
	       UNPACKJ_N(16)	/* 65535 levels */
/* -- end of dispatch -- */
	    case 37:
	       skip(m, m->cup.bit_skip);
	    case 36:
	       s += 3 * 64;
	 }			/* end switch */
      }				/* end j loop */
   }				/* end i loop */


}
/*-------------------------------------------------------------------------*/
IN_OUT audio_decode(MPEG *m, unsigned char *bs, signed short *pcm)
{
   return m->cup.audio_decode_routine(m, bs, pcm);
}
/*-------------------------------------------------------------------------*/
IN_OUT L2audio_decode(void *mv, unsigned char *bs, signed short *pcm)
{
   MPEG *m = mv;
   int sync, prot;
   IN_OUT in_out;

   load_init(m, bs);		/* initialize bit getter */
/* test sync */
   in_out.in_bytes = 0;		/* assume fail */
   in_out.out_bytes = 0;
   sync = load(m,12);
   if (sync != 0xFFF)
      return in_out;		/* sync fail */

   load(m,3);			/* skip id and option (checked by init) */
   prot = load(m,1);		/* load prot bit */
   load(m,6);			/* skip to pad */
   m->cup.pad = load(m,1);
   load(m,1);			/* skip to mode */
   m->cup.stereo_sb = look_joint[load(m,4)];
   if (prot)
      load(m,4);			/* skip to data */
   else
      load(m,20);			/* skip crc */

   unpack_ba(m);			/* unpack bit allocation */
   unpack_sfs(m);		/* unpack scale factor selectors */
   unpack_sf(m);			/* unpack scale factor */
   unpack_samp(m);		/* unpack samples */

   m->cup.sbt(m, m->cup.sample, pcm, 36);
/*-----------*/
   in_out.in_bytes = m->cup.framebytes + m->cup.pad;
   in_out.out_bytes = m->cup.outbytes;

   return in_out;
}
/*-------------------------------------------------------------------------*/
#include "cupini.c"		/* initialization */
#include "cupL1.c"		/* Layer I */
/*-------------------------------------------------------------------------*/