// SPDX-License-Identifier: GPL-2.0
  /*
   * Generate lookup table for the table-driven CRC64 calculation.
   *
   * gen_crc64table is executed in kernel build time and generates
   * lib/crc64table.h. This header is included by lib/crc64.c for
   * the table-driven CRC64 calculation.
   *
   * See lib/crc64.c for more information about which specification
   * and polynomial arithmetic that gen_crc64table.c follows to
   * generate the lookup table.
   *
   * Copyright 2018 SUSE Linux.
   *   Author: Coly Li <colyli@suse.de>
   */
  #include <inttypes.h>
  #include <stdio.h>
  
  #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL
  
  static uint64_t crc64_table[256] = {0};
  
  static void generate_crc64_table(void)
  {
  	uint64_t i, j, c, crc;
  
  	for (i = 0; i < 256; i++) {
  		crc = 0;
  		c = i << 56;
  
  		for (j = 0; j < 8; j++) {
  			if ((crc ^ c) & 0x8000000000000000ULL)
  				crc = (crc << 1) ^ CRC64_ECMA182_POLY;
  			else
  				crc <<= 1;
  			c <<= 1;
  		}
  
  		crc64_table[i] = crc;
  	}
  }
  
  static void print_crc64_table(void)
  {
  	int i;
  
  	printf("/* this file is generated - do not edit */
  
  ");
  	printf("#include <linux/types.h>
  ");
  	printf("#include <linux/cache.h>
  
  ");
  	printf("static const u64 ____cacheline_aligned crc64table[256] = {
  ");
  	for (i = 0; i < 256; i++) {
  		printf("\t0x%016" PRIx64 "ULL", crc64_table[i]);
  		if (i & 0x1)
  			printf(",
  ");
  		else
  			printf(", ");
  	}
  	printf("};
  ");
  }
  
  int main(int argc, char *argv[])
  {
  	generate_crc64_table();
  	print_crc64_table();
  	return 0;
  }