libxfs/gen_crc32table.c

   1 #include <stdio.h>
   2 #include "crc32defs.h"
   3 #include <inttypes.h>
   4
   5 #define ENTRIES_PER_LINE 4
   6
   7 #if CRC_LE_BITS > 8
   8 # define LE_TABLE_ROWS (CRC_LE_BITS/8)
   9 # define LE_TABLE_SIZE 256
  10 #else
  11 # define LE_TABLE_ROWS 1
  12 # define LE_TABLE_SIZE (1 << CRC_LE_BITS)
  13 #endif
  14
  15 #if CRC_BE_BITS > 8
  16 # define BE_TABLE_ROWS (CRC_BE_BITS/8)
  17 # define BE_TABLE_SIZE 256
  18 #else
  19 # define BE_TABLE_ROWS 1
  20 # define BE_TABLE_SIZE (1 << CRC_BE_BITS)
  21 #endif
  22
  23 static uint32_t crc32table_le[LE_TABLE_ROWS][256];
  24 static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
  25
  26 /*
  27  * big endian ordered CRC not used by XFS.
  28 static uint32_t crc32table_be[BE_TABLE_ROWS][256];
  29  */
  30
  31 /**
  32  * crc32init_le() - allocate and initialize LE table data
  33  *
  34  * crc is the crc of the byte i; other entries are filled in based on the
  35  * fact that crctable[i^j] = crctable[i] ^ crctable[j].
  36  *
  37  */
  38 static void crc32init_le_generic(const uint32_t polynomial,
  39                                  uint32_t (*tab)[256])
  40 {
  41         unsigned i, j;
  42         uint32_t crc = 1;
  43
  44         tab[0][0] = 0;
  45
  46         for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
  47                 crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
  48                 for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
  49                         tab[0][i + j] = crc ^ tab[0][j];
  50         }
  51         for (i = 0; i < LE_TABLE_SIZE; i++) {
  52                 crc = tab[0][i];
  53                 for (j = 1; j < LE_TABLE_ROWS; j++) {
  54                         crc = tab[0][crc & 0xff] ^ (crc >> 8);
  55                         tab[j][i] = crc;
  56                 }
  57         }
  58 }
  59
  60 static void crc32init_le(void)
  61 {
  62         crc32init_le_generic(CRCPOLY_LE, crc32table_le);
  63 }
  64
  65 static void crc32cinit_le(void)
  66 {
  67         crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
  68 }
  69
  70 /**
  71  * crc32init_be() - allocate and initialize BE table data
  72  */
  73 #if 0 /* not used */
  74 static void crc32init_be(void)
  75 {
  76         unsigned i, j;
  77         uint32_t crc = 0x80000000;
  78
  79         crc32table_be[0][0] = 0;
  80
  81         for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
  82                 crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0);
  83                 for (j = 0; j < i; j++)
  84                         crc32table_be[0][i + j] = crc ^ crc32table_be[0][j];
  85         }
  86         for (i = 0; i < BE_TABLE_SIZE; i++) {
  87                 crc = crc32table_be[0][i];
  88                 for (j = 1; j < BE_TABLE_ROWS; j++) {
  89                         crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
  90                         crc32table_be[j][i] = crc;
  91                 }
  92         }
  93 }
  94 #endif
  95
  96 static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
  97 {
  98         int i, j;
  99
 100         for (j = 0 ; j < rows; j++) {
 101                 printf("{");
 102                 for (i = 0; i < len - 1; i++) {
 103                         if (i % ENTRIES_PER_LINE == 0)
 104                                 printf("\n");
 105                         printf("%s(0x%8.8xL), ", trans, table[j][i]);
 106                 }
 107                 printf("%s(0x%8.8xL)},\n", trans, table[j][len - 1]);
 108         }
 109 }
 110
 111 int main(int argc, char** argv)
 112 {
 113         printf("/* this file is generated - do not edit */\n\n");
 114
 115         if (CRC_LE_BITS > 1) {
 116                 crc32init_le();
 117                 printf("static u32 crc32table_le[%d][%d] = {",
 118                        LE_TABLE_ROWS, LE_TABLE_SIZE);
 119                 output_table(crc32table_le, LE_TABLE_ROWS,
 120                              LE_TABLE_SIZE, "tole");
 121                 printf("};\n");
 122         }
 123
 124 #if 0   /* not used by xfsprogs */
 125         if (CRC_BE_BITS > 1) {
 126                 crc32init_be();
 127                 printf("static u32 crc32table_be[%d][%d] = {",
 128                        BE_TABLE_ROWS, BE_TABLE_SIZE);
 129                 output_table(crc32table_be, LE_TABLE_ROWS,
 130                              BE_TABLE_SIZE, "tobe");
 131                 printf("};\n");
 132         }
 133 #endif
 134         if (CRC_LE_BITS > 1) {
 135                 crc32cinit_le();
 136                 printf("static u32 crc32ctable_le[%d][%d] = {",
 137                        LE_TABLE_ROWS, LE_TABLE_SIZE);
 138                 output_table(crc32ctable_le, LE_TABLE_ROWS,
 139                              LE_TABLE_SIZE, "tole");
 140                 printf("};\n");
 141         }
 142
 143         return 0;
 144 }