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/*
* This file is part of the Code::Blocks IDE and licensed under the GNU Lesser General Public License, version 3
* http://www.gnu.org/licenses/lgpl-3.0.html
*
* $Revision: 5547 $
* $Id: crc32.cpp 5547 2009-04-27 15:49:29Z biplab $
* $HeadURL: svn+ssh://jenslody@svn.berlios.de/svnroot/repos/codeblocks/trunk/src/sdk/crc32.cpp $
*/
/*
This code was taken from:
http://wikisource.org/wiki/CRC32_Checksum_function
by an unknown author...
I just changed the function names to match the conventions used
in the rest of the project.
Yiannis Mandravellos <mandrav@codeblocks.org>
*/
#include <wx/string.h>
#include <wx/file.h>
#include "crc32.h"
#include "globals.h"
static wxUint32 *GetCRC32Table( wxUint32 *crc_table )
{
// First call to this function? Or after freeing the memory?
if ( !crc_table )
{
// Allocate memory
crc_table = new wxUint32[256];
// Was the allocation succesfull?
if ( crc_table )
{
// Generate the crc table
for(unsigned int i = 0; i < 256; ++i)
{
wxUint32 crc = i;
for (unsigned int j = 8; j > 0; --j)
{
if (crc & 1) crc = (crc >> 1) ^ 0xEDB88320UL;
else crc >>= 1;
}
crc_table[i] = crc;
}
}
}
// Return the new pointer
return ( crc_table ) ;
}
wxUint32 wxCrc32::FromFile(const wxString& file)
{
wxFile f(file);
wxString contents = cbReadFileContents(f);
if (contents.IsEmpty())
return 0;
return FromString(contents);
}
wxUint32 wxCrc32::FromString(const wxString& text)
{
static wxUint32 *crc_table = NULL;
wxUint32 crc = 0;
unsigned int i = 0;
if (!text.IsEmpty())
{
// Get the crc table, on first call, generate, otherwise do nothing
crc_table = GetCRC32Table( crc_table ) ;
// Do we have a crc table?
if ( crc_table )
{
// Calculate the checksum
crc = 0xFFFFFFFFUL;
while (text[i])
#if wxCHECK_VERSION(2, 9, 0)
{ crc = (crc>>8) ^ crc_table[ (crc^(text[i++].GetValue())) & 0xFF ]; }
#else
{ crc = (crc>>8) ^ crc_table[ (crc^(text[i++])) & 0xFF ]; }
#endif
crc ^= 0xFFFFFFFFUL ;
}
}
// If we have a crc table, delete it from memory
if ( crc_table ) { delete[] crc_table; }
// Set it to a null pointer, the have it (re)created on next calls to this
// function
crc_table = NULL;
// Return the checksum result
return( crc ) ;
}
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