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-rwxr-xr-xC/7zCrc.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/C/7zCrc.c b/C/7zCrc.c
new file mode 100755
index 0000000..5801dab
--- /dev/null
+++ b/C/7zCrc.c
@@ -0,0 +1,74 @@
+/* 7zCrc.c -- CRC32 calculation
+2009-11-23 : Igor Pavlov : Public domain */
+
+#include "7zCrc.h"
+#include "CpuArch.h"
+
+#define kCrcPoly 0xEDB88320
+
+#ifdef MY_CPU_LE
+#define CRC_NUM_TABLES 8
+#else
+#define CRC_NUM_TABLES 1
+#endif
+
+typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
+
+static CRC_FUNC g_CrcUpdate;
+UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
+
+#if CRC_NUM_TABLES == 1
+
+#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
+
+static UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
+{
+ const Byte *p = (const Byte *)data;
+ for (; size > 0; size--, p++)
+ v = CRC_UPDATE_BYTE_2(v, *p);
+ return v;
+}
+
+#else
+
+UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
+UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
+
+#endif
+
+UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
+{
+ return g_CrcUpdate(v, data, size, g_CrcTable);
+}
+
+UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
+{
+ return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
+}
+
+void MY_FAST_CALL CrcGenerateTable()
+{
+ UInt32 i;
+ for (i = 0; i < 256; i++)
+ {
+ UInt32 r = i;
+ unsigned j;
+ for (j = 0; j < 8; j++)
+ r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
+ g_CrcTable[i] = r;
+ }
+ #if CRC_NUM_TABLES == 1
+ g_CrcUpdate = CrcUpdateT1;
+ #else
+ for (; i < 256 * CRC_NUM_TABLES; i++)
+ {
+ UInt32 r = g_CrcTable[i - 256];
+ g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
+ }
+ g_CrcUpdate = CrcUpdateT4;
+ #ifdef MY_CPU_X86_OR_AMD64
+ if (!CPU_Is_InOrder())
+ g_CrcUpdate = CrcUpdateT8;
+ #endif
+ #endif
+}