toolame-02l/crc.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include "common.h"
   4 #include "crc.h"
   5
   6 /*****************************************************************************
   7 *
   8 *  CRC error protection package
   9 *
  10 *****************************************************************************/
  11
  12 void CRC_calc (frame_info * frame, unsigned int bit_alloc[2][SBLIMIT],
  13                unsigned int scfsi[2][SBLIMIT], unsigned int *crc)
  14 {
  15   int i, k;
  16   frame_header *header = frame->header;
  17   int nch = frame->nch;
  18   int sblimit = frame->sblimit;
  19   int jsbound = frame->jsbound;
  20   al_table *alloc = frame->alloc;
  21
  22   *crc = 0xffff;                /* changed from '0' 92-08-11 shn */
  23   update_CRC (header->bitrate_index, 4, crc);
  24   update_CRC (header->sampling_frequency, 2, crc);
  25   update_CRC (header->padding, 1, crc);
  26   update_CRC (header->extension, 1, crc);
  27   update_CRC (header->mode, 2, crc);
  28   update_CRC (header->mode_ext, 2, crc);
  29   update_CRC (header->copyright, 1, crc);
  30   update_CRC (header->original, 1, crc);
  31   update_CRC (header->emphasis, 2, crc);
  32
  33   for (i = 0; i < sblimit; i++)
  34     for (k = 0; k < ((i < jsbound) ? nch : 1); k++)
  35       update_CRC (bit_alloc[k][i], (*alloc)[i][0].bits, crc);
  36
  37   for (i = 0; i < sblimit; i++)
  38     for (k = 0; k < nch; k++)
  39       if (bit_alloc[k][i])
  40         update_CRC (scfsi[k][i], 2, crc);
  41 }
  42
  43 void update_CRC (unsigned int data, unsigned int length, unsigned int *crc)
  44 {
  45   unsigned int masking, carry;
  46
  47   masking = 1 << length;
  48
  49   while ((masking >>= 1)) {
  50     carry = *crc & 0x8000;
  51     *crc <<= 1;
  52     if (!carry ^ !(data & masking))
  53       *crc ^= CRC16_POLYNOMIAL;
  54   }
  55   *crc &= 0xffff;
  56 }
  57
  58 void
  59 CRC_calcDAB (frame_info * frame,
  60              unsigned int bit_alloc[2][SBLIMIT],
  61              unsigned int scfsi[2][SBLIMIT],
  62              unsigned int scalar[2][3][SBLIMIT], unsigned int *crc,
  63              int packed)
  64 {
  65   int i, j, k;
  66   int nch = frame->nch;
  67   int nb_scalar;
  68   int f[5] = { 0, 4, 8, 16, 30 };
  69   int first, last;
  70
  71   first = f[packed];
  72   last = f[packed + 1];
  73   if (last > frame->sblimit)
  74     last = frame->sblimit;
  75
  76   nb_scalar = 0;
  77   *crc = 0x0;
  78   for (i = first; i < last; i++)
  79     for (k = 0; k < nch; k++)
  80       if (bit_alloc[k][i])      /* above jsbound, bit_alloc[0][i] == ba[1][i] */
  81         switch (scfsi[k][i]) {
  82         case 0:
  83           for (j = 0; j < 3; j++) {
  84             nb_scalar++;
  85             update_CRCDAB (scalar[k][j][i] >> 3, 3, crc);
  86           }
  87           break;
  88         case 1:
  89         case 3:
  90           nb_scalar += 2;
  91           update_CRCDAB (scalar[k][0][i] >> 3, 3, crc);
  92           update_CRCDAB (scalar[k][2][i] >> 3, 3, crc);
  93           break;
  94         case 2:
  95           nb_scalar++;
  96           update_CRCDAB (scalar[k][0][i] >> 3, 3, crc);
  97         }
  98 }
  99
 100 void update_CRCDAB (unsigned int data, unsigned int length, unsigned int *crc)
 101 {
 102   unsigned int masking, carry;
 103
 104   masking = 1 << length;
 105
 106   while ((masking >>= 1)) {
 107     carry = *crc & 0x80;
 108     *crc <<= 1;
 109     if (!carry ^ !(data & masking))
 110       *crc ^= CRC8_POLYNOMIAL;
 111   }
 112   *crc &= 0xff;
 113 }