Rewrite GetHashForString to fix a small copyright problem. (A license
that says "you can use this code however you want" doesn't necessarily imply "you can modify it, too", just that you can use it.) Besides, hardcoding that huge table was ugly since it can be derived easily.
This commit is contained in:
Glenn Maynard
+26
-124
@@ -7,7 +7,6 @@
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Copyright (c) 2001-2002 by the person(s) listed below. All rights reserved.
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Chris Danford
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Peter S. May (GetHashForString implementation)
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-----------------------------------------------------------------------------
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*/
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@@ -23,6 +22,9 @@
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#include <map>
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#include <set>
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#include "RageTimer.h"
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#include "RageLog.h"
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#if !defined(WIN32)
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#include <dirent.h>
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#endif
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@@ -351,129 +353,32 @@ void GetCwd(CString &s)
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s = buf;
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}
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unsigned int GetHashForString ( CString string )
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/* Reference: http://www.theorem.com/java/CRC32.java, rewritten by Glenn Maynard.
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* Public domain. */
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unsigned int GetHashForString ( CString s )
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{
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/*
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* RageCRC32.cpp
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*
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* Original code
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* COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or
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* code or tables extracted from it, as desired without restriction.
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*
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* Code was extracted from IETF Internet Draft
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* draft-ietf-tsvwg-sctpcsum-00 at URI
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* http://www.ietf.org/proceedings/01dec/I-D/draft-ietf-tsvwg-sctpcsum-00.txt
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*
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* Adaptation
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* Copyright (C) 2002 Peter S. May.
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* SourceForge ID: drokulix
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*
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* - Values in table changed from long int to int
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*
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* Chris:
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* Moved this code out of RageCRC32 since it's not terribly long. Thanks Dro Kulix!
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*/
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static unsigned tab[256];
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static bool initted = false;
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if(!initted)
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{
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initted = true;
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const unsigned POLY = 0xEDB88320;
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/*
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* COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or
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* code or tables extracted from it, as desired without restriction.
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*
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* First, the polynomial itself and its table of feedback terms. The
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* polynomial is
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* X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
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*
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* Note that we take it "backwards" and put the highest-order term in
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* the lowest-order bit. The X^32 term is "implied"; the LSB is the
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* X^31 term, etc. The X^0 term (usually shown as "+1") results in
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* the MSB being 1
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*
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* Note that the usual hardware shift register implementation, which
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* is what we're using (we're merely optimizing it by doing eight-bit
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* chunks at a time) shifts bits into the lowest-order term. In our
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* implementation, that means shifting towards the right. Why do we
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* do it this way? Because the calculated CRC must be transmitted in
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* order from highest-order term to lowest-order term. UARTs transmit
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* characters in order from LSB to MSB. By storing the CRC this way
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* we hand it to the UART in the order low-byte to high-byte; the UART
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* sends each low-bit to hight-bit; and the result is transmission bit
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* by bit from highest- to lowest-order term without requiring any bit
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* shuffling on our part. Reception works similarly
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*
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* The feedback terms table consists of 256, 32-bit entries. Notes
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*
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* The table can be generated at runtime if desired; code to do so
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* is shown later. It might not be obvious, but the feedback
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* terms simply represent the results of eight shift/xor opera
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* tions for all combinations of data and CRC register values
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*
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* The values must be right-shifted by eight bits by the "updcrc
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* logic; the shift must be unsigned (bring in zeroes). On some
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* hardware you could probably optimize the shift in assembler by
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* using byte-swap instructions
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* polynomial $edb88320
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*/
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for(int i = 0; i < 256; ++i)
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{
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tab[i] = i;
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for(int j = 0; j < 8; ++j)
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{
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if(tab[i] & 1) tab[i] = (tab[i] >> 1) ^ POLY;
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else tab[i] >>= 1;
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}
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}
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}
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static const unsigned int crc32_tab[] = {
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0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
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0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
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0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
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0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
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0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
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0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
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0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
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0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
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0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
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0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
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0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
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0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
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0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
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0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
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0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
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0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
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0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
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0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
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0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
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0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
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0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
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0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
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0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
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0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
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0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
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0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
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0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
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0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
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0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
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0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
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0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
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0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
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0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
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0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
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0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
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0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
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0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
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0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
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0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
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0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
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0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
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0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
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0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
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0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
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0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
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0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
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0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
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0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
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0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
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0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
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0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
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0x2d02ef8d
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};
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/* Return a 32-bit CRC of the contents of the buffer. */
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unsigned int crc32val = 0;
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for( unsigned i=0; i < string.size(); i++ )
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crc32val = crc32_tab[(crc32val ^ string[i]) & 0xff] ^ (crc32val >> 8);
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return crc32val;
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unsigned crc = 0;
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for(unsigned i = 0; i < s.size(); ++i)
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crc = (crc >> 8) ^ tab[(crc ^ s[i]) & 0xFF];
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return crc;
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}
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bool DoStat(CString sPath, struct stat *st)
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@@ -1010,9 +915,6 @@ struct File {
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}
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};
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#include "RageTimer.h"
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#include "RageLog.h"
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struct FileSet
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{
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set<File> files;
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Reference in New Issue
Block a user