X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcheck%2Fcrc64_fast.c;fp=lzma%2Fcheck%2Fcrc64_fast.c;h=52af29ed48d80b52c4bcd85ce8aef8f1eb97ca15;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage

diff --git a/lzma/check/crc64_fast.c b/lzma/check/crc64_fast.c
new file mode 100644
index 0000000..52af29e
--- /dev/null
+++ b/lzma/check/crc64_fast.c
@@ -0,0 +1,72 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       crc64.c
+/// \brief      CRC64 calculation
+///
+/// Calculate the CRC64 using the slice-by-four algorithm. This is the same
+/// idea that is used in crc32_fast.c, but for CRC64 we use only four tables
+/// instead of eight to avoid increasing CPU cache usage.
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "check.h"
+#include "crc_macros.h"
+
+
+#ifdef WORDS_BIGENDIAN
+#	define A1(x) ((x) >> 56)
+#else
+#	define A1 A
+#endif
+
+
+// See the comments in crc32_fast.c. They aren't duplicated here.
+extern LZMA_API(uint64_t)
+lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
+{
+	crc = ~crc;
+
+#ifdef WORDS_BIGENDIAN
+	crc = bswap64(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);
+
+		while (buf < limit) {
+#ifdef WORDS_BIGENDIAN
+			const uint32_t tmp = (crc >> 32)
+					^ *(const uint32_t *)(buf);
+#else
+			const uint32_t tmp = crc ^ *(const uint32_t *)(buf);
+#endif
+			buf += 4;
+
+			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 = bswap64(crc);
+#endif
+
+	return ~crc;
+}