use pregenerated CRC32 lookup tables for retain on Win32 and GNU/Linux

This code could be possible reused on low-end targets with limited RAM.

code to generate lookup table:
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/* CRC lookup table and initial state. */
uint32_t crc32_table[256];

/* Generate CRC32 lookup table. */
void GenerateCRC32Table(void)
{
unsigned int i, j;
/* Use CRC-32-IEEE 802.3 polynomial 0x04C11DB7 (bit reflected). */
uint32_t poly = 0xEDB88320;

for (i = 0; i <= 0xFF; i++)
{
uint32_t c = i;
for (j = 0 ; j < 8 ; j++)
c = (c & 1) ? (c >> 1 ) ^ poly : (c >> 1);
crc32_table[i] = c;
}
}

void main(void)
{
GenerateCRC32Table();
int j=0;
for(int i=0; i<256; i++) {
printf("0x%08X, ", crc32_table[i]);
if (++j >= 8) {
j = 0;
printf("\n");
}
}
}
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/*

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Template C code used to produce target Ethercat C code.

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Copyright (C) 2011-2014: Laurent BESSARD, Edouard TISSERANT

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Distributed under the terms of the GNU Lesser General Public License as

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published by the Free Software Foundation; either version 2 of the License, or

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(at your option) any later version.

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See COPYING file for copyrights details.

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*/

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#include "iec_types_all.h"

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#define FREE 0

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#define ACQUIRED 1

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#define ANSWERED 2

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long SDOLock = FREE;

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extern long AtomicCompareExchange(long* atomicvar,long compared, long exchange);

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int AcquireSDOLock() {

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	return AtomicCompareExchange(&SDOLock, FREE, ACQUIRED) == FREE;

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}

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void SDOAnswered() {

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	AtomicCompareExchange(&SDOLock, ACQUIRED, ANSWERED);

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}

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int HasAnswer() {

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	return SDOLock == ANSWERED;

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}

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void ReleaseSDOLock() {

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	AtomicCompareExchange(&SDOLock, ANSWERED, FREE);

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}

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int __init_etherlab_ext()

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{

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    SDOLock = FREE;

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    return 0;

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}

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void __cleanup_etherlab_ext()

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{

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}

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void __retrieve_etherlab_ext()

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{

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}

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void __publish_etherlab_ext()

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{

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}