1 files changed, 75 insertions, 0 deletions
diff --git a/src/liblzma/check/crc64_fast.c b/src/liblzma/check/crc64_fast.c
new file mode 100644
index 00000000..00fbfd53
--- /dev/null
+++ b/src/liblzma/check/crc64_fast.c
@@ -0,0 +1,75 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       crc64.c
+/// \brief      CRC64 calculation
+//
+//  This code has been put into the public domain.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "check.h"
+#include "crc_macros.h"
+
+
+#ifdef WORDS_BIGENDIAN
+#	define A1(x) ((x) >> 56)
+#else
+#	define A1 A
+#endif
+
+
+// See comments in crc32.c.
+extern LZMA_API uint64_t
+lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
+{
+	crc = ~crc;
+
+#ifdef WORDS_BIGENDIAN
+	crc = bswap_64(crc);
+#endif
+
+	if (size > 4) {
+		while ((uintptr_t)(buf) & 3) {
+			crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
+			--size;
+		}
+
+		const uint8_t *const limit = buf + (size & ~(size_t)(3));
+		size &= (size_t)(3);
+
+		// Calculate the CRC64 using the slice-by-four algorithm.
+		//
+		// In contrast to CRC32 code, this one seems to be fastest
+		// with -O3 -fomit-frame-pointer.
+		while (buf < limit) {
+#ifdef WORDS_BIGENDIAN
+			const uint32_t tmp = (crc >> 32) ^ *(uint32_t *)(buf);
+#else
+			const uint32_t tmp = crc ^ *(uint32_t *)(buf);
+#endif
+			buf += 4;
+
+			// It is critical for performance, that
+			// the crc variable is XORed between the
+			// two table-lookup pairs.
+			crc = lzma_crc64_table[3][A(tmp)]
+			    ^ lzma_crc64_table[2][B(tmp)]
+			    ^ S32(crc)
+			    ^ lzma_crc64_table[1][C(tmp)]
+			    ^ lzma_crc64_table[0][D(tmp)];
+		}
+	}
+
+	while (size-- != 0)
+		crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
+
+#ifdef WORDS_BIGENDIAN
+	crc = bswap_64(crc);
+#endif
+
+	return ~crc;
+}