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      1 #include <stdio.h>
      2 #include "crc32c_defs.h"
      3 #include <inttypes.h>
      4 
      5 #define ENTRIES_PER_LINE 4
      6 
      7 #if CRC_LE_BITS <= 8
      8 #define LE_TABLE_SIZE (1 << CRC_LE_BITS)
      9 #else
     10 #define LE_TABLE_SIZE 256
     11 #endif
     12 
     13 #if CRC_BE_BITS <= 8
     14 #define BE_TABLE_SIZE (1 << CRC_BE_BITS)
     15 #else
     16 #define BE_TABLE_SIZE 256
     17 #endif
     18 
     19 static uint32_t crc32ctable_le[8][256];
     20 static uint32_t crc32ctable_be[8][256];
     21 
     22 /**
     23  * crc32cinit_le() - allocate and initialize LE table data
     24  *
     25  * crc is the crc of the byte i; other entries are filled in based on the
     26  * fact that crctable[i^j] = crctable[i] ^ crctable[j].
     27  *
     28  */
     29 static void crc32cinit_le(void)
     30 {
     31 	unsigned i, j;
     32 	uint32_t crc = 1;
     33 
     34 	crc32ctable_le[0][0] = 0;
     35 
     36 	for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
     37 		crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
     38 		for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
     39 			crc32ctable_le[0][i + j] = crc ^ crc32ctable_le[0][j];
     40 	}
     41 	for (i = 0; i < LE_TABLE_SIZE; i++) {
     42 		crc = crc32ctable_le[0][i];
     43 		for (j = 1; j < 8; j++) {
     44 			crc = crc32ctable_le[0][crc & 0xff] ^ (crc >> 8);
     45 			crc32ctable_le[j][i] = crc;
     46 		}
     47 	}
     48 }
     49 
     50 /**
     51  * crc32cinit_be() - allocate and initialize BE table data
     52  */
     53 static void crc32cinit_be(void)
     54 {
     55 	unsigned i, j;
     56 	uint32_t crc = 0x80000000;
     57 
     58 	crc32ctable_be[0][0] = 0;
     59 
     60 	for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
     61 		crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0);
     62 		for (j = 0; j < i; j++)
     63 			crc32ctable_be[0][i + j] = crc ^ crc32ctable_be[0][j];
     64 	}
     65 	for (i = 0; i < BE_TABLE_SIZE; i++) {
     66 		crc = crc32ctable_be[0][i];
     67 		for (j = 1; j < 8; j++) {
     68 			crc = crc32ctable_be[0][(crc >> 24) & 0xff] ^
     69 			      (crc << 8);
     70 			crc32ctable_be[j][i] = crc;
     71 		}
     72 	}
     73 }
     74 
     75 static void output_table(uint32_t table[8][256], int len, char trans)
     76 {
     77 	int i, j;
     78 
     79 	for (j = 0 ; j < 8; j++) {
     80 		printf("static const uint32_t t%d_%ce[] = {", j, trans);
     81 		for (i = 0; i < len - 1; i++) {
     82 			if ((i % ENTRIES_PER_LINE) == 0)
     83 				printf("\n");
     84 			printf("to%ce(0x%8.8xL),", trans, table[j][i]);
     85 			if ((i % ENTRIES_PER_LINE) != (ENTRIES_PER_LINE - 1))
     86 				printf(" ");
     87 		}
     88 		printf("to%ce(0x%8.8xL)};\n\n", trans, table[j][len - 1]);
     89 
     90 		if (trans == 'l') {
     91 			if ((j+1)*8 >= CRC_LE_BITS)
     92 				break;
     93 		} else {
     94 			if ((j+1)*8 >= CRC_BE_BITS)
     95 				break;
     96 		}
     97 	}
     98 }
     99 
    100 int main(int argc, char **argv)
    101 {
    102 	printf("/*\n");
    103 	printf(" * crc32ctable.h - CRC32c tables\n");
    104 	printf(" *    this file is generated - do not edit\n");
    105 	printf(" *	# gen_crc32ctable > crc32c_table.h\n");
    106 	printf(" *    with\n");
    107 	printf(" *	CRC_LE_BITS = %d\n", CRC_LE_BITS);
    108 	printf(" *	CRC_BE_BITS = %d\n", CRC_BE_BITS);
    109 	printf(" */\n");
    110 	printf("#include <stdint.h>\n");
    111 
    112 	if (CRC_LE_BITS > 1) {
    113 		crc32cinit_le();
    114 		output_table(crc32ctable_le, LE_TABLE_SIZE, 'l');
    115 	}
    116 
    117 	if (CRC_BE_BITS > 1) {
    118 		crc32cinit_be();
    119 		output_table(crc32ctable_be, BE_TABLE_SIZE, 'b');
    120 	}
    121 
    122 	return 0;
    123 }
    124