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lib/gen_crc32table.c
2.25 KB
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#include <stdio.h> #include "crc32defs.h" #include <inttypes.h> #define ENTRIES_PER_LINE 4 #define LE_TABLE_SIZE (1 << CRC_LE_BITS) #define BE_TABLE_SIZE (1 << CRC_BE_BITS) |
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static uint32_t crc32table_le[4][LE_TABLE_SIZE]; static uint32_t crc32table_be[4][BE_TABLE_SIZE]; |
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/** * crc32init_le() - allocate and initialize LE table data * * crc is the crc of the byte i; other entries are filled in based on the * fact that crctable[i^j] = crctable[i] ^ crctable[j]. * */ static void crc32init_le(void) { unsigned i, j; uint32_t crc = 1; |
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crc32table_le[0][0] = 0; |
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for (i = 1 << (CRC_LE_BITS - 1); i; i >>= 1) { crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0); for (j = 0; j < LE_TABLE_SIZE; j += 2 * i) |
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crc32table_le[0][i + j] = crc ^ crc32table_le[0][j]; } for (i = 0; i < LE_TABLE_SIZE; i++) { crc = crc32table_le[0][i]; for (j = 1; j < 4; j++) { crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8); crc32table_le[j][i] = crc; } |
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} } /** * crc32init_be() - allocate and initialize BE table data */ static void crc32init_be(void) { unsigned i, j; uint32_t crc = 0x80000000; |
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crc32table_be[0][0] = 0; |
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for (i = 1; i < BE_TABLE_SIZE; i <<= 1) { crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0); for (j = 0; j < i; j++) |
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crc32table_be[0][i + j] = crc ^ crc32table_be[0][j]; } for (i = 0; i < BE_TABLE_SIZE; i++) { crc = crc32table_be[0][i]; for (j = 1; j < 4; j++) { crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8); crc32table_be[j][i] = crc; } |
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} } |
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static void output_table(uint32_t table[4][256], int len, char *trans) |
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{ |
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int i, j; |
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for (j = 0 ; j < 4; j++) { printf("{"); for (i = 0; i < len - 1; i++) { if (i % ENTRIES_PER_LINE == 0) printf(" "); printf("%s(0x%8.8xL), ", trans, table[j][i]); } printf("%s(0x%8.8xL)}, ", trans, table[j][len - 1]); |
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} |
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} int main(int argc, char** argv) { printf("/* this file is generated - do not edit */ "); if (CRC_LE_BITS > 1) { crc32init_le(); |
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printf("static const u32 crc32table_le[4][256] = {"); |
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output_table(crc32table_le, LE_TABLE_SIZE, "tole"); printf("}; "); } if (CRC_BE_BITS > 1) { crc32init_be(); |
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printf("static const u32 crc32table_be[4][256] = {"); |
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output_table(crc32table_be, BE_TABLE_SIZE, "tobe"); printf("}; "); } return 0; } |