Last change
on this file since 585 was
585,
checked in by Sam Hocevar, 11 years ago
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tool: compute and display SPEC item CRCs.
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File size:
1.1 KB
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1 | /* |
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2 | * Abuse - dark 2D side-scrolling platform game |
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3 | * Copyright (c) 1995 Crack dot Com |
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4 | * Copyright (c) 2005-2011 Sam Hocevar <sam@hocevar.net> |
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5 | * |
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6 | * This software was released into the Public Domain. As with most public |
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7 | * domain software, no warranty is made or implied by Crack dot Com, by |
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8 | * Jonathan Clark, or by Sam Hocevar. |
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9 | */ |
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10 | |
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11 | #if defined HAVE_CONFIG_H |
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12 | # include "config.h" |
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13 | #endif |
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14 | |
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15 | #include "crc.h" |
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16 | |
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17 | uint16_t calc_crc(void *buf, size_t len) |
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18 | { |
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19 | uint8_t *data = (uint8_t *)buf; |
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20 | uint8_t c1 = 0, c2 = 0; |
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21 | |
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22 | while (len--) |
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23 | c2 += (c1 += *data++); |
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24 | |
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25 | return (c2 << 8) | c1; |
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26 | } |
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27 | |
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28 | |
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29 | |
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30 | uint32_t crc_file(bFILE *fp) |
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31 | { |
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32 | uint8_t crc1=0,crc2=0,crc3=0,crc4=0; |
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33 | |
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34 | int size=0x1000; |
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35 | uint8_t *buffer=(uint8_t *)malloc(size),*c; |
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36 | long l=fp->file_size(); |
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37 | long cur_pos=fp->tell(); |
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38 | fp->seek(0,0); |
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39 | while (l) |
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40 | { |
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41 | int nr=fp->read(buffer,size); |
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42 | if (nr==0) l=0; |
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43 | else |
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44 | { |
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45 | l-=nr; |
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46 | for (c=buffer; nr; nr--,c++) |
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47 | { |
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48 | crc1+=*c; |
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49 | crc2+=crc1; |
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50 | crc3+=crc2; |
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51 | crc4+=crc3; |
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52 | } |
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53 | } |
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54 | } |
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55 | fp->seek(cur_pos,0); |
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56 | free(buffer); |
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57 | return (crc1|(crc2<<8)|(crc3<<16)|(crc4<<24)); |
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58 | } |
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