#!/usr/bin/env python # Copyright 2024 Google LLC # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from __future__ import print_function CRC_POLY = 0x04C11DB7 CRC_WIDTH = 32 def precompute_table(bits): lookup_table = [] for i in xrange(2**bits): rr = i << (CRC_WIDTH - bits) for x in xrange(bits): if rr & 0x80000000: rr = (rr << 1) ^ CRC_POLY else: rr <<= 1 lookup_table.append(rr & 0xffffffff) return lookup_table print('static const uint32_t s_lookup_table[] = {') for entry in precompute_table(4): print(' 0x{:08x},'.format(entry)) print('};')