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

2019-01-06, Andrey Skvortsov

68f4f2d4516b

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:
[---------------------------------------------------------------------]

/* 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");
}
}
}
[---------------------------------------------------------------------]

#!/usr/bin/env python

# -*- coding: utf-8 -*-

# This file is part of Beremiz, a Integrated Development Environment for

# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.

# See COPYING file for copyrights details.

# This program is free software; you can redistribute it and/or

# modify it under the terms of the GNU General Public License

# as published by the Free Software Foundation; either version 2

# of the License, or (at your option) any later version.

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

from __future__ import absolute_import

import os

from POULibrary import POULibrary

from py_ext.PythonFileCTNMixin import PythonFileCTNMixin

import util.paths as paths

class PythonLibrary(POULibrary):

def GetLibraryPath(self):

return paths.AbsNeighbourFile(__file__, "pous.xml")

def Generate_C(self, buildpath, varlist, IECCFLAGS):

plc_python_filepath = paths.AbsNeighbourFile(__file__, "plc_python.c")

plc_python_file = open(plc_python_filepath, 'r')

plc_python_code = plc_python_file.read()

plc_python_file.close()

python_eval_fb_list = []

for v in varlist:

if v["vartype"] == "FB" and v["type"] in ["PYTHON_EVAL",

"PYTHON_POLL"]:

python_eval_fb_list.append(v)

python_eval_fb_count = max(1, len(python_eval_fb_list))

# prepare python code

plc_python_code = plc_python_code % {

"python_eval_fb_count": python_eval_fb_count}

Gen_Pythonfile_path = os.path.join(buildpath, "py_ext.c")

pythonfile = open(Gen_Pythonfile_path, 'w')

pythonfile.write(plc_python_code)

pythonfile.close()

return (["py_ext"], [(Gen_Pythonfile_path, IECCFLAGS)], True), ""

class PythonFile(PythonFileCTNMixin):

def GetIconName(self):

return "Pyfile"

beremiz