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1 #include <stdio.h>
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2
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3 #include "os9.h"
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4
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5 int os9_crc(OS9_MODULE_t *mod)
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6 {
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7 int i;
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8 u_char crc[3] = {0xff, 0xff, 0xff};
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9 u_char *ptr = (u_char *) mod;
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10 u_char a;
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11
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12 for (i = 0; i < INT(mod->size); i++)
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13 {
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14 a = *(ptr++);
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15
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16 a ^= crc[0];
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17 crc[0] = crc[1];
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18 crc[1] = crc[2];
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19 crc[1] ^= (a >> 7);
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20 crc[2] = (a << 1);
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21 crc[1] ^= (a >> 2);
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22 crc[2] ^= (a << 6);
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23 a ^= (a << 1);
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24 a ^= (a << 2);
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25 a ^= (a << 4);
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26 if (a & 0x80) {
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27 crc[0] ^= 0x80;
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28 crc[2] ^= 0x21;
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29 }
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30 }
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31 if ((crc[0] == OS9_CRC0) &&
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32 (crc[1] == OS9_CRC1) &&
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33 (crc[2] == OS9_CRC2))
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34 return 1;
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35
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36 return 0;
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37 }
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38
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39 int os9_header(OS9_MODULE_t *mod)
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40 {
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41 u_char tmp = 0x00;
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42 u_char *ptr = (u_char *) mod;
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43 int i;
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44
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45 for (i = 0; i < OS9_HEADER_SIZE; i++)
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46 tmp ^= *(ptr++);
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47
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48 return tmp;
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49 }
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