LXR linux/lib/gen_crc32table.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <stdio.h>
   3#include "../include/linux/crc32poly.h"
   4#include "../include/generated/autoconf.h"
   5#include "crc32defs.h"
   6#include <inttypes.h>
   7
   8#define ENTRIES_PER_LINE 4
   9
  10#if CRC_LE_BITS > 8
  11# define LE_TABLE_ROWS (CRC_LE_BITS/8)
  12# define LE_TABLE_SIZE 256
  13#else
  14# define LE_TABLE_ROWS 1
  15# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
  16#endif
  17
  18#if CRC_BE_BITS > 8
  19# define BE_TABLE_ROWS (CRC_BE_BITS/8)
  20# define BE_TABLE_SIZE 256
  21#else
  22# define BE_TABLE_ROWS 1
  23# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
  24#endif
  25
  26static uint32_t crc32table_le[LE_TABLE_ROWS][256];
  27static uint32_t crc32table_be[BE_TABLE_ROWS][256];
  28static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
  29
  30/**
  31 * crc32init_le() - allocate and initialize LE table data
  32 *
  33 * crc is the crc of the byte i; other entries are filled in based on the
  34 * fact that crctable[i^j] = crctable[i] ^ crctable[j].
  35 *
  36 */
  37static void crc32init_le_generic(const uint32_t polynomial,
  38                                 uint32_t (*tab)[256])
  39{
  40        unsigned i, j;
  41        uint32_t crc = 1;
  42
  43        tab[0][0] = 0;
  44
  45        for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
  46                crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
  47                for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
  48                        tab[0][i + j] = crc ^ tab[0][j];
  49        }
  50        for (i = 0; i < LE_TABLE_SIZE; i++) {
  51                crc = tab[0][i];
  52                for (j = 1; j < LE_TABLE_ROWS; j++) {
  53                        crc = tab[0][crc & 0xff] ^ (crc >> 8);
  54                        tab[j][i] = crc;
  55                }
  56        }
  57}
  58
  59static void crc32init_le(void)
  60{
  61        crc32init_le_generic(CRC32_POLY_LE, crc32table_le);
  62}
  63
  64static void crc32cinit_le(void)
  65{
  66        crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
  67}
  68
  69/**
  70 * crc32init_be() - allocate and initialize BE table data
  71 */
  72static void crc32init_be(void)
  73{
  74        unsigned i, j;
  75        uint32_t crc = 0x80000000;
  76
  77        crc32table_be[0][0] = 0;
  78
  79        for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
  80                crc = (crc << 1) ^ ((crc & 0x80000000) ? CRC32_POLY_BE : 0);
  81                for (j = 0; j < i; j++)
  82                        crc32table_be[0][i + j] = crc ^ crc32table_be[0][j];
  83        }
  84        for (i = 0; i < BE_TABLE_SIZE; i++) {
  85                crc = crc32table_be[0][i];
  86                for (j = 1; j < BE_TABLE_ROWS; j++) {
  87                        crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
  88                        crc32table_be[j][i] = crc;
  89                }
  90        }
  91}
  92
  93static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
  94{
  95        int i, j;
  96
  97        for (j = 0 ; j < rows; j++) {
  98                printf("{");
  99                for (i = 0; i < len - 1; i++) {
 100                        if (i % ENTRIES_PER_LINE == 0)
 101                                printf("\n");
 102                        printf("%s(0x%8.8xL), ", trans, table[j][i]);
 103                }
 104                printf("%s(0x%8.8xL)},\n", trans, table[j][len - 1]);
 105        }
 106}
 107
 108int main(int argc, char** argv)
 109{
 110        printf("/* this file is generated - do not edit */\n\n");
 111
 112        if (CRC_LE_BITS > 1) {
 113                crc32init_le();
 114                printf("static const u32 ____cacheline_aligned "
 115                       "crc32table_le[%d][%d] = {",
 116                       LE_TABLE_ROWS, LE_TABLE_SIZE);
 117                output_table(crc32table_le, LE_TABLE_ROWS,
 118                             LE_TABLE_SIZE, "tole");
 119                printf("};\n");
 120        }
 121
 122        if (CRC_BE_BITS > 1) {
 123                crc32init_be();
 124                printf("static const u32 ____cacheline_aligned "
 125                       "crc32table_be[%d][%d] = {",
 126                       BE_TABLE_ROWS, BE_TABLE_SIZE);
 127                output_table(crc32table_be, LE_TABLE_ROWS,
 128                             BE_TABLE_SIZE, "tobe");
 129                printf("};\n");
 130        }
 131        if (CRC_LE_BITS > 1) {
 132                crc32cinit_le();
 133                printf("static const u32 ____cacheline_aligned "
 134                       "crc32ctable_le[%d][%d] = {",
 135                       LE_TABLE_ROWS, LE_TABLE_SIZE);
 136                output_table(crc32ctable_le, LE_TABLE_ROWS,
 137                             LE_TABLE_SIZE, "tole");
 138                printf("};\n");
 139        }
 140
 141        return 0;
 142}
 143