lib/gen_crc32table.c

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