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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/gen_crc32table.c
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.c82
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;
+}

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