HGKeeper

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

import sys

# import pytest

# import xvfbwrapper

def init_environment():

"""Append module root directory to sys.path"""

try:

import Beremiz as _Beremiz

except ImportError:

sys.path.append(

os.path.abspath(

os.path.join(

os.path.dirname(__file__), '..', '..')

)

init_environment()

# Something seems to be broken in Beremiz application,

# because after tests in test_application.py during Xvfb shutdown

# pytest returns error message:

# pytest: Fatal IO error 11 (Die Ressource ist zur Zeit nicht verfügbar) on X server :2821.

# As a result of that pytest returns code 1 as some tests were failed,

# but they aren't.

# To avoid this Xvfb is launched and killed not by pytest.

# $ Xvfb :42 -screen 0 1280x1024x24 &

# $ export DISPLAY=:42

# $ pytest --timeout=10 ./tests/tools

# $ pkill -9 Xvfb

# TODO: find root of this problem.

# vdisplay = None

# @pytest.fixture(scope="session", autouse=True)

# def start_xvfb_server(request):

# global vdisplay

# vdisplay = xvfbwrapper.Xvfb(width=1280, height=720)

# vdisplay.start()

# request.addfinalizer(stop_xvfb_server)

# def stop_xvfb_server():

# if vdisplay is not None:

# vdisplay.stop()

beremiz