iupini.ch

DSP c64优化 ACT spraa14 mp3优化实例 与其优化应用报告配套

/*--  grouped 5 level lookup table 7 bit token --*/
   for (i = 0; i < 128; i++)
   {
      code = i;
      for (j = 0; j < 3; j++)
      {
         group5_table[i][j] = (char) ((code % 5) - 2);
         code /= 5;
      }
   }
/*--  grouped 9 level lookup table 10 bit token --*/
   for (i = 0; i < 1024; i++)
   {
      code = i;
      for (j = 0; j < 3; j++)
      {
         group9_table[i][j] = (short) ((code % 9) - 4);
         code /= 9;
      }
   }


}

/*---------------------------------------------------------*/
int i_audio_decode_initL1(MPEG_HEAD * h, int framebytes_arg,
                   int reduction_code, int transform_code, int convert_code,
                          int freq_limit);
void i_sbt_init();

/*---------------------------------------------------------*/
/* mpeg_head defined in mhead.h  frame bytes is without pad */
int i_audio_decode_init(MPEG_HEAD * h, int framebytes_arg,
                   int reduction_code, int transform_code, int convert_code,
                        int freq_limit)
{
   int i, j, k;
   static int first_pass = 1;
   int abcd_index;
   long samprate;
   int limit;
   int bit_code;

   if (first_pass)
   {
      table_init();
      first_pass = 0;
   }

/* check if code handles */
   if (h->option == 3)                /* layer I */
      return i_audio_decode_initL1(h, framebytes_arg,
                  reduction_code, transform_code, convert_code, freq_limit);
   if (h->option != 2)
      return 0;                        /* layer II only */


   unpack_routine = unpack;

   transform_code = transform_code;        /* not used, asm compatability */
   bit_code = 0;
   if (convert_code & 8)
      bit_code = 1;
   convert_code = convert_code & 3;        /* higher bits used by dec8 freq cvt */
   if (reduction_code < 0)
      reduction_code = 0;
   if (reduction_code > 2)
      reduction_code = 2;
   if (freq_limit < 1000)
      freq_limit = 1000;


   framebytes = framebytes_arg;

/* compute abcd index for bit allo table selection */
   if (h->id)                        /* mpeg 1 */
      abcd_index = lookqt[h->mode][h->sr_index][h->br_index];
   else
      abcd_index = 4;                /* mpeg 2 */
   for (i = 0; i < 4; i++)
      for (j = 0; j < 16; j++)
         bat[i][j] = look_bat[abcd_index][i][j];
   for (i = 0; i < 4; i++)
      nbat[i] = look_nbat[abcd_index][i];
   max_sb = nbat[0] + nbat[1] + nbat[2] + nbat[3];
/*----- compute nsb_limit --------*/
   samprate = sr_table[4 * h->id + h->sr_index];
   nsb_limit = (freq_limit * 64L + samprate / 2) / samprate;
/*- caller limit -*/
/*---- limit = 0.94*(32>>reduction_code);  ----*/
   limit = (32 >> reduction_code);
   if (limit > 8)
      limit--;
   if (nsb_limit > limit)
      nsb_limit = limit;
   if (nsb_limit > max_sb)
      nsb_limit = max_sb;

   outvalues = 1152 >> reduction_code;
   if (h->mode != 3)
   {                                /* adjust for 2 channel modes */
      for (i = 0; i < 4; i++)
         nbat[i] *= 2;
      max_sb *= 2;
      nsb_limit *= 2;
   }

/* set sbt function */
   nsbt = 36;
   k = 1 + convert_code;
   if (h->mode == 3)
   {
      k = 0;
   }
   sbt = sbt_table[bit_code][reduction_code][k];
   outvalues *= out_chans[k];
   if (bit_code != 0)
      outbytes = outvalues;
   else
#if __TMS320C55X__ || _TMS320C5XX || _TMS320C27XX
      outbytes = 2 * outvalues;
#else
      outbytes = sizeof(short) * outvalues;
#endif

   decinfo.channels = out_chans[k];
   decinfo.outvalues = outvalues;
   decinfo.samprate = samprate >> reduction_code;
   if (bit_code != 0)
      decinfo.bits = 8;
   else
#if __TMS320C55X__ || _TMS320C5XX || _TMS320C27XX
      decinfo.bits = 2 * 8;
#else
      decinfo.bits = sizeof(short) * 8;
#endif

   decinfo.framebytes = framebytes;
   decinfo.type = 0;


/* clear sample buffer, unused sub bands must be 0 */
   for (i = 0; i < 2304; i++)
      sample[i] = 0;


/* init sub-band transform */
   i_sbt_init();

   return 1;
}
/*---------------------------------------------------------*/
void i_audio_decode_info(DEC_INFO * info)
{
   *info = decinfo;                /* info return, call after init */
}
/*---------------------------------------------------------*/

/* ***********************************************************
* THIS PROGRAM IS PROVIDED "AS IS". TI MAKES NO WARRANTIES OR
* REPRESENTATIONS, EITHER EXPRESS, IMPLIED OR STATUTORY, 
* INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS 
* FOR A PARTICULAR PURPOSE, LACK OF VIRUSES, ACCURACY OR 
* COMPLETENESS OF RESPONSES, RESULTS AND LACK OF NEGLIGENCE. 
* TI DISCLAIMS ANY WARRANTY OF TITLE, QUIET ENJOYMENT, QUIET 
* POSSESSION, AND NON-INFRINGEMENT OF ANY THIRD PARTY 
* INTELLECTUAL PROPERTY RIGHTS WITH REGARD TO THE PROGRAM OR 
* YOUR USE OF THE PROGRAM.
*
* IN NO EVENT SHALL TI BE LIABLE FOR ANY SPECIAL, INCIDENTAL, 
* CONSEQUENTIAL OR INDIRECT DAMAGES, HOWEVER CAUSED, ON ANY 
* THEORY OF LIABILITY AND WHETHER OR NOT TI HAS BEEN ADVISED 
* OF THE POSSIBILITY OF SUCH DAMAGES, ARISING IN ANY WAY OUT 
* OF THIS AGREEMENT, THE PROGRAM, OR YOUR USE OF THE PROGRAM. 
* EXCLUDED DAMAGES INCLUDE, BUT ARE NOT LIMITED TO, COST OF 
* REMOVAL OR REINSTALLATION, COMPUTER TIME, LABOR COSTS, LOSS 
* OF GOODWILL, LOSS OF PROFITS, LOSS OF SAVINGS, OR LOSS OF 
* USE OR INTERRUPTION OF BUSINESS. IN NO EVENT WILL TI'S 
* AGGREGATE LIABILITY UNDER THIS AGREEMENT OR ARISING OUT OF 
* YOUR USE OF THE PROGRAM EXCEED FIVE HUNDRED DOLLARS 
* (U.S.$500).
*
* Unless otherwise stated, the Program written and copyrighted 
* by Texas Instruments is distributed as "freeware".  You may, 
* only under TI's copyright in the Program, use and modify the 
* Program without any charge or restriction.  You may 
* distribute to third parties, provided that you transfer a 
* copy of this license to the third party and the third party 
* agrees to these terms by its first use of the Program. You 
* must reproduce the copyright notice and any other legend of 
* ownership on each copy or partial copy, of the Program.
*
* You acknowledge and agree that the Program contains 
* copyrighted material, trade secrets and other TI proprietary 
* information and is protected by copyright laws, 
* international copyright treaties, and trade secret laws, as 
* well as other intellectual property laws.  To protect TI's 
* rights in the Program, you agree not to decompile, reverse 
* engineer, disassemble or otherwise translate any object code 
* versions of the Program to a human-readable form.  You agree 
* that in no event will you alter, remove or destroy any 
* copyright notice included in the Program.  TI reserves all 
* rights not specifically granted under this license. Except 
* as specifically provided herein, nothing in this agreement 
* shall be construed as conferring by implication, estoppel, 
* or otherwise, upon you, any license or other right under any 
* TI patents, copyrights or trade secrets.
*
* You may not use the Program in non-TI devices.
* ********************************************************* */