X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcheck%2Fcrc64_small.c;fp=lzma%2Fcheck%2Fcrc64_small.c;h=55d72316bce753973676a0538fb003d88bbcc9f9;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage

diff --git a/lzma/check/crc64_small.c b/lzma/check/crc64_small.c
new file mode 100644
index 0000000..55d7231
--- /dev/null
+++ b/lzma/check/crc64_small.c
@@ -0,0 +1,53 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       crc64_small.c
+/// \brief      CRC64 calculation (size-optimized)
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "check.h"
+
+
+static uint64_t crc64_table[256];
+
+
+static void
+crc64_init(void)
+{
+	static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
+
+	for (size_t b = 0; b < 256; ++b) {
+		uint64_t r = b;
+		for (size_t i = 0; i < 8; ++i) {
+			if (r & 1)
+				r = (r >> 1) ^ poly64;
+			else
+				r >>= 1;
+		}
+
+		crc64_table[b] = r;
+	}
+
+	return;
+}
+
+
+extern LZMA_API(uint64_t)
+lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
+{
+	mythread_once(crc64_init);
+
+	crc = ~crc;
+
+	while (size != 0) {
+		crc = crc64_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
+		--size;
+	}
+
+	return ~crc;
+}