psi.c 10.4 KB
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/*****************************************************************************
 * psi.c: common PSI functions
 *----------------------------------------------------------------------------
 * (c)2001-2002 VideoLAN
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 * $Id$
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 *
 * Authors: Arnaud de Bossoreille de Ribou <bozo@via.ecp.fr>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 *----------------------------------------------------------------------------
 *
 *****************************************************************************/


#include "config.h"

#include <stdio.h>
#include <stdlib.h>

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#if defined(HAVE_INTTYPES_H)
#include <inttypes.h>
#elif defined(HAVE_STDINT_H)
#include <stdint.h>
#endif

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#include "dvbpsi.h"
#include "dvbpsi_private.h"
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#include "psi.h"
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/*****************************************************************************
 * s_crc32_table
 *****************************************************************************
 * This table is used to compute a PSI CRC byte per byte instead of bit per
 * bit. It's been generated by 'gen_crc' in the 'misc' directory:
 * 
 *   uint32_t table[256];
 *   uint32_t i, j, k;
 *
 *   for(i = 0; i < 256; i++)
 *   {
 *     k = 0;
 *     for (j = (i << 24) | 0x800000; j != 0x80000000; j <<= 1)
 *       k = (k << 1) ^ (((k ^ j) & 0x80000000) ? 0x04c11db7 : 0);
 *     table[i] = k;
 *   }
 *
 * A CRC is computed like this:
 *
 *   initialization
 *   --------------
 *   uint32_t i_crc = 0xffffffff;
 *
 *   for each data byte do
 *   ---------------------
 *   i_crc = (i_crc << 8) ^ s_crc32_table[(i_crc >> 24) ^ (data_byte)];
 *****************************************************************************/
static uint32_t s_crc32_table[256] =
{
  0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
  0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
  0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
  0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
  0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
  0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
  0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
  0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
  0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
  0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
  0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
  0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
  0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
  0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
  0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
  0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
  0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
  0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
  0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
  0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
  0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
  0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
  0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
  0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
  0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
  0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
  0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
  0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
  0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
  0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
  0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
  0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
  0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
  0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
  0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
  0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
  0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
  0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
  0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
  0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
  0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
  0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
  0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
  0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
  0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
  0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
  0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
  0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
  0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
  0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
  0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
  0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
  0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
  0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
  0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
  0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
  0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
  0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
  0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
  0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
};


/*****************************************************************************
 * dvbpsi_NewPSISection
 *****************************************************************************
 * Creation of a new dvbpsi_psi_section_t structure.
 *****************************************************************************/
dvbpsi_psi_section_t * dvbpsi_NewPSISection(int i_max_size)
{
  /* Allocate the dvbpsi_psi_section_t structure */
  dvbpsi_psi_section_t * p_section
                = (dvbpsi_psi_section_t*)malloc(sizeof(dvbpsi_psi_section_t));

  if(p_section != NULL)
  {
    /* Allocate the p_data memory area */
    p_section->p_data = (uint8_t*)malloc(i_max_size * sizeof(uint8_t));

    if(p_section->p_data != NULL)
    {
      p_section->p_payload_end = p_section->p_data;
    }
    else
    {
      free(p_section);
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      return NULL;
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    }

    p_section->p_next = NULL;
  }

  return p_section;
}


/*****************************************************************************
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 * dvbpsi_DeletePSISections
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 *****************************************************************************
 * Destruction of a dvbpsi_psi_section_t structure.
 *****************************************************************************/
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void dvbpsi_DeletePSISections(dvbpsi_psi_section_t * p_section)
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{
  while(p_section != NULL)
  {
    dvbpsi_psi_section_t* p_next = p_section->p_next;

    if(p_section->p_data != NULL)
      free(p_section->p_data);

    free(p_section);
    p_section = p_next;
  }
}


/*****************************************************************************
 * dvbpsi_ValidPSISection
 *****************************************************************************
 * Check the CRC_32 if the section has b_syntax_indicator set.
 *****************************************************************************/
int dvbpsi_ValidPSISection(dvbpsi_psi_section_t* p_section)
{
  if(p_section->b_syntax_indicator)
  {
    /* Check the CRC_32 if b_syntax_indicator is 0 */
    uint32_t i_crc = 0xffffffff;
    uint8_t* p_byte = p_section->p_data;

    while(p_byte < p_section->p_payload_end + 4)
    {
      i_crc = (i_crc << 8) ^ s_crc32_table[(i_crc >> 24) ^ (*p_byte)];
      p_byte++;
    }

    if(i_crc == 0)
    {
      return 1;
    }
    else
    {
      DVBPSI_ERROR_ARG("misc PSI",
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                       "Bad CRC_32 (0x%08x) !!!", i_crc);
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      return 0;
    }
  }
  else
  {
    /* No check to do if b_syntax_indicator is 0 */
    return 1;
  }
}


/*****************************************************************************
 * dvbpsi_BuildPSISection
 *****************************************************************************
 * Build the section based on the information in the structure.
 *****************************************************************************/
void dvbpsi_BuildPSISection(dvbpsi_psi_section_t* p_section)
{
  uint8_t* p_byte = p_section->p_data;

  /* table_id */
  p_section->p_data[0] = p_section->i_table_id;
  /* setion_syntax_indicator | private_indicator |
     first 4 MSB of section_length */
  p_section->p_data[1] =   (p_section->b_syntax_indicator ? 0x80 : 0x00)
                         | (p_section->b_private_indicator ? 0x40 : 0x00)
                         | 0x30 /* reserved bits set to 1 */
                         | ((p_section->i_length >> 8) & 0x0f);
  /* 8 LSB of section_length */
  p_section->p_data[2] = p_section->i_length & 0xff;

  /* Optional part of a PSI section */
  if(p_section->b_syntax_indicator)
  {
    /* 8 MSB of table_id_extension */
    p_section->p_data[3] = (p_section->i_extension >> 8) & 0xff;
    /* 8 LSB of table_id_extension */
    p_section->p_data[4] = p_section->i_extension & 0xff;
    /* 5 bits of version_number | current_next_indicator */
    p_section->p_data[5] =   0xc0 /* reserved bits set to 1 */
                           | ((p_section->i_version & 0x1f) << 1)
                           | (p_section->b_current_next ? 0x01 : 0x00);
    /* section_number */
    p_section->p_data[6] = p_section->i_number;
    /* last_section_number */
    p_section->p_data[7] = p_section->i_last_number;

    /* CRC_32 */
    p_section->i_crc = 0xffffffff;

    while(p_byte < p_section->p_payload_end)
    {
      p_section->i_crc =   (p_section->i_crc << 8)
                         ^ s_crc32_table[(p_section->i_crc >> 24) ^ (*p_byte)];
      p_byte++;
    }

    p_section->p_payload_end[0] = (p_section->i_crc >> 24) & 0xff;
    p_section->p_payload_end[1] = (p_section->i_crc >> 16) & 0xff;
    p_section->p_payload_end[2] = (p_section->i_crc >> 8) & 0xff;
    p_section->p_payload_end[3] = p_section->i_crc & 0xff;
#ifdef DEBUG
    if(!dvbpsi_ValidPSISection(p_section))
    {
      DVBPSI_ERROR("misc PSI", "********************************************");
      DVBPSI_ERROR("misc PSI", "* Generated PSI section has a bad CRC_32.  *");
      DVBPSI_ERROR("misc PSI", "* THIS IS A BUG, PLEASE REPORT TO THE LIST *");
      DVBPSI_ERROR("misc PSI", "*  ---  libdvbpsi-devel@videolan.org  ---  *");
      DVBPSI_ERROR("misc PSI", "********************************************");
    }
#endif
  }
}