1 /*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <stdint.h>
18
19 /* Calculate CRC32 how the STM32F4xx family does */
20
21 static unsigned int crc_table[] =
22 {
23 0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9,
24 0x130476DC ,0x17C56B6B ,0x1A864DB2 ,0x1E475005,
25 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61,
26 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD
27 };
28
crc32_word(uint32_t crc,uint32_t data)29 static uint32_t crc32_word(uint32_t crc, uint32_t data)
30 {
31 crc = crc ^ data;
32
33 crc = (crc << 4) ^ crc_table[crc >> 28];
34 crc = (crc << 4) ^ crc_table[crc >> 28];
35 crc = (crc << 4) ^ crc_table[crc >> 28];
36 crc = (crc << 4) ^ crc_table[crc >> 28];
37 crc = (crc << 4) ^ crc_table[crc >> 28];
38 crc = (crc << 4) ^ crc_table[crc >> 28];
39 crc = (crc << 4) ^ crc_table[crc >> 28];
40 crc = (crc << 4) ^ crc_table[crc >> 28];
41
42 return crc;
43 }
44
stm32f4_crc32(uint8_t * buffer,int length)45 uint32_t stm32f4_crc32(uint8_t *buffer, int length)
46 {
47 uint32_t *data = (uint32_t *)buffer;
48 uint32_t word;
49 uint32_t crc = ~0;
50 int i;
51
52 /* word by word crc32 */
53 for (i=0; i<(length>>2); i++) {
54 crc = crc32_word(crc, data[i]);
55 }
56
57 /* zero pad last word if required */
58 if (length & 0x3) {
59 for (i*=4, word=0; i<length; i++)
60 word |= buffer[i] << ((i & 0x3) * 8);
61 crc = crc32_word(crc, word);
62 }
63
64 return crc;
65 }
66