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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/gen_crc32table.c | |
download | lwn-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz lwn-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'lib/gen_crc32table.c')
-rw-r--r-- | lib/gen_crc32table.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/lib/gen_crc32table.c b/lib/gen_crc32table.c new file mode 100644 index 000000000000..bea5d97df991 --- /dev/null +++ b/lib/gen_crc32table.c @@ -0,0 +1,82 @@ +#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) + +static uint32_t crc32table_le[LE_TABLE_SIZE]; +static uint32_t crc32table_be[BE_TABLE_SIZE]; + +/** + * 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; + + crc32table_le[0] = 0; + + 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) + crc32table_le[i + j] = crc ^ crc32table_le[j]; + } +} + +/** + * crc32init_be() - allocate and initialize BE table data + */ +static void crc32init_be(void) +{ + unsigned i, j; + uint32_t crc = 0x80000000; + + crc32table_be[0] = 0; + + for (i = 1; i < BE_TABLE_SIZE; i <<= 1) { + crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0); + for (j = 0; j < i; j++) + crc32table_be[i + j] = crc ^ crc32table_be[j]; + } +} + +static void output_table(uint32_t table[], int len, char *trans) +{ + int i; + + for (i = 0; i < len - 1; i++) { + if (i % ENTRIES_PER_LINE == 0) + printf("\n"); + printf("%s(0x%8.8xL), ", trans, table[i]); + } + printf("%s(0x%8.8xL)\n", trans, table[len - 1]); +} + +int main(int argc, char** argv) +{ + printf("/* this file is generated - do not edit */\n\n"); + + if (CRC_LE_BITS > 1) { + crc32init_le(); + printf("static const u32 crc32table_le[] = {"); + output_table(crc32table_le, LE_TABLE_SIZE, "tole"); + printf("};\n"); + } + + if (CRC_BE_BITS > 1) { + crc32init_be(); + printf("static const u32 crc32table_be[] = {"); + output_table(crc32table_be, BE_TABLE_SIZE, "tobe"); + printf("};\n"); + } + + return 0; +} |