gen_crc32table.c

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    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 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 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 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 }

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FreeBSD/Linux Kernel Cross Reference sys/lib/gen_crc32table.c

FreeBSD/Linux Kernel Cross Reference
sys/lib/gen_crc32table.c