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;
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