1 files changed, 58 insertions, 0 deletions
diff --git a/lib/crc/crc64.c b/lib/crc/crc64.c
new file mode 100644
index 000000000000..5b1b17057f0a
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+++ b/lib/crc/crc64.c
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+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Normal 64-bit CRC calculation.
+ *
+ * This is a basic crc64 implementation following ECMA-182 specification,
+ * which can be found from,
+ * https://www.ecma-international.org/publications/standards/Ecma-182.htm
+ *
+ * Dr. Ross N. Williams has a great document to introduce the idea of CRC
+ * algorithm, here the CRC64 code is also inspired by the table-driven
+ * algorithm and detail example from this paper. This paper can be found
+ * from,
+ * http://www.ross.net/crc/download/crc_v3.txt
+ *
+ * crc64table[256] is the lookup table of a table-driven 64-bit CRC
+ * calculation, which is generated by gen_crc64table.c in kernel build
+ * time. The polynomial of crc64 arithmetic is from ECMA-182 specification
+ * as well, which is defined as,
+ *
+ * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
+ * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
+ * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
+ * x^7 + x^4 + x + 1
+ *
+ * crc64nvmetable[256] uses the CRC64 polynomial from the NVME NVM Command Set
+ * Specification and uses least-significant-bit first bit order:
+ *
+ * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 +
+ * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 +
+ * x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x^9 + x^6 + x^4 + x^3 + 1
+ *
+ * Copyright 2018 SUSE Linux.
+ *   Author: Coly Li <colyli@suse.de>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/crc64.h>
+#include "crc64table.h"
+
+MODULE_DESCRIPTION("CRC64 calculations");
+MODULE_LICENSE("GPL v2");
+
+u64 crc64_be_generic(u64 crc, const u8 *p, size_t len)
+{
+	while (len--)
+		crc = (crc << 8) ^ crc64table[(crc >> 56) ^ *p++];
+	return crc;
+}
+EXPORT_SYMBOL_GPL(crc64_be_generic);
+
+u64 crc64_nvme_generic(u64 crc, const u8 *p, size_t len)
+{
+	while (len--)
+		crc = (crc >> 8) ^ crc64nvmetable[(crc & 0xff) ^ *p++];
+	return crc;
+}
+EXPORT_SYMBOL_GPL(crc64_nvme_generic);