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
  26 static uint32_t crc32table_le[LE_TABLE_ROWS][256];
  27 static uint32_t crc32table_be[BE_TABLE_ROWS][256];
  28 static 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  */
  37 static 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
  59 static void crc32init_le(void)
  60 {
  61         crc32init_le_generic(CRC32_POLY_LE, crc32table_le);
  62 }
  63
  64 static 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  */
  72 static 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
  93 static 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
 108 int 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 }