lib/gen_crc32table.c

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