// SPDX-License-Identifier: GPL-2.0
/*
 * This host program runs at kernel build time and generates the lookup tables
 * used by the generic CRC64 code.
 *
 * Copyright 2018 SUSE Linux.
 *   Author: Coly Li <colyli@suse.de>
 */
#include <inttypes.h>
#include <stdio.h>

#define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL
#define CRC64_NVME_POLY 0x9A6C9329AC4BC9B5ULL

static uint64_t crc64_table[256] = {0};
static uint64_t crc64_nvme_table[256] = {0};

static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly)
{
        uint64_t i, j, c, crc;

        for (i = 0; i < 256; i++) {
                crc = 0ULL;
                c = i;

                for (j = 0; j < 8; j++) {
                        if ((crc ^ (c >> j)) & 1)
                                crc = (crc >> 1) ^ poly;
                        else
                                crc >>= 1;
                }
                table[i] = crc;
        }
}

static void generate_crc64_table(uint64_t table[256], uint64_t poly)
{
        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) ^ poly;
                        else
                                crc <<= 1;
                        c <<= 1;
                }

                table[i] = crc;
        }
}

static void output_table(uint64_t table[256])
{
        int i;

        for (i = 0; i < 256; i++) {
                printf("\t0x%016" PRIx64 "ULL", table[i]);
                if (i & 0x1)
                        printf(",\n");
                else
                        printf(", ");
        }
        printf("};\n");
}

static void print_crc64_tables(void)
{
        printf("/* this file is generated - do not edit */\n\n");
        printf("#include <linux/types.h>\n");
        printf("#include <linux/cache.h>\n\n");
        printf("static const u64 ____cacheline_aligned crc64table[256] = {\n");
        output_table(crc64_table);

        printf("\nstatic const u64 ____cacheline_aligned crc64nvmetable[256] = {\n");
        output_table(crc64_nvme_table);
}

int main(int argc, char *argv[])
{
        generate_crc64_table(crc64_table, CRC64_ECMA182_POLY);
        generate_reflected_crc64_table(crc64_nvme_table, CRC64_NVME_POLY);
        print_crc64_tables();
        return 0;
}