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      1 /******************************************************************************
      2  *                                                                            *
      3  * Copyright (C) 2018 The Android Open Source Project
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at:
      8  *
      9  * http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  *
     17  *****************************************************************************
     18  * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore
     19 */
     20 #include <ixheaacd_type_def.h>
     21 
     22 #include "ixheaacd_bitbuffer.h"
     23 #include "ixheaacd_sbr_crc.h"
     24 #include "ixheaacd_sbr_const.h"
     25 
     26 static VOID ixheaacd_calc_chk_sum(WORD16* crc_state, WORD32 stream_data,
     27                                   WORD32 num_bits) {
     28   WORD32 i;
     29   WORD32 data_bit_mask = (1 << (num_bits - 1));
     30   WORD16 crc10 = SBR_CRC_POLY;
     31   WORD16 crc_mask = (1 << 9);
     32   WORD16 crc_state_local = *crc_state;
     33 
     34   for (i = 0; i < num_bits; i++) {
     35     WORD32 bit0, bit1;
     36     bit0 = ((crc_state_local & crc_mask) ? 1 : 0);
     37     bit1 = ((data_bit_mask & stream_data) ? 1 : 0);
     38     bit0 ^= bit1;
     39     crc_state_local = (WORD16)((WORD32)(crc_state_local & 0x0000FFFF) << 1);
     40     if (bit0) {
     41       crc_state_local ^= crc10;
     42     }
     43     data_bit_mask = (data_bit_mask >> 1);
     44   }
     45   *crc_state = crc_state_local;
     46   return;
     47 }
     48 
     49 static PLATFORM_INLINE WORD32 ixheaacd_sbr_crc(ia_bit_buf_struct* it_bit_buff,
     50                                                WORD32 num_crc_bits) {
     51   WORD32 i;
     52   WORD32 num_full_bytes, rem_bits;
     53   WORD32 byte_value;
     54   WORD16 crc_state = 0;
     55 
     56   num_full_bytes = (num_crc_bits >> 3);
     57   rem_bits = (num_crc_bits & 0x7);
     58 
     59   for (i = 0; i < num_full_bytes; i++) {
     60     byte_value = ixheaacd_read_bits_buf(it_bit_buff, 8);
     61     ixheaacd_calc_chk_sum(&crc_state, byte_value, 8);
     62   }
     63 
     64   byte_value = ixheaacd_read_bits_buf(it_bit_buff, rem_bits);
     65   ixheaacd_calc_chk_sum(&crc_state, byte_value, rem_bits);
     66 
     67   return (crc_state & 0x03FF);
     68 }
     69 
     70 FLAG ixheaacd_sbr_crccheck(ia_bit_buf_struct* it_bit_buff,
     71                            WORD32 crc_bits_len) {
     72   struct ia_bit_buf_struct it_bit_buff_local = {0};
     73   WORD32 num_crc_bits;
     74   WORD32 calc_crc_sum;
     75   WORD32 bits_available;
     76   WORD32 crc_check_sum;
     77 
     78   crc_check_sum = ixheaacd_read_bits_buf(it_bit_buff, SBR_CYC_REDCY_CHK_BITS);
     79 
     80   it_bit_buff_local = *it_bit_buff;
     81 
     82   bits_available = it_bit_buff->cnt_bits;
     83 
     84   if (bits_available <= 0) {
     85     return 0;
     86   }
     87 
     88   num_crc_bits =
     89       (crc_bits_len > bits_available) ? bits_available : crc_bits_len;
     90 
     91   calc_crc_sum = ixheaacd_sbr_crc(&it_bit_buff_local, num_crc_bits);
     92 
     93   if (calc_crc_sum != crc_check_sum) {
     94     return 0;
     95   }
     96   return 1;
     97 }
     98