[Qemu-devel] [RFC PATCH 2/9] jhash: add linux kernel jhashtable in qemu

[Zhang Chen]

From: zhangchen <address@hidden>

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Signed-off-by: zhangchen <address@hidden>
---
 include/qemu/jhash.h | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 include/qemu/jhash.h

diff --git a/include/qemu/jhash.h b/include/qemu/jhash.h
new file mode 100644
index 0000000..f6cc7b3
--- /dev/null
+++ b/include/qemu/jhash.h
@@ -0,0 +1,52 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2015 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2015 FUJITSU LIMITED
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * Author: Zhang Chen <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_JHASH_H__
+#define QEMU_JHASH_H__
+
+/*
+ * hashtable relation copy from linux kernel jhash
+ */
+static inline uint32_t rol32(uint32_t word, unsigned int shift)
+{
+    return (word << shift) | (word >> (32 - shift));
+}
+
+/* __jhash_mix -- mix 3 32-bit values reversibly. */
+#define __jhash_mix(a, b, c)                \
+{                                           \
+    a -= c;  a ^= rol32(c, 4);  c += b;     \
+    b -= a;  b ^= rol32(a, 6);  a += c;     \
+    c -= b;  c ^= rol32(b, 8);  b += a;     \
+    a -= c;  a ^= rol32(c, 16); c += b;     \
+    b -= a;  b ^= rol32(a, 19); a += c;     \
+    c -= b;  c ^= rol32(b, 4);  b += a;     \
+}
+
+/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
+#define __jhash_final(a, b, c)  \
+{                               \
+    c ^= b; c -= rol32(b, 14);  \
+    a ^= c; a -= rol32(c, 11);  \
+    b ^= a; b -= rol32(a, 25);  \
+    c ^= b; c -= rol32(b, 16);  \
+    a ^= c; a -= rol32(c, 4);   \
+    b ^= a; b -= rol32(a, 14);  \
+    c ^= b; c -= rol32(b, 24);  \
+}
+
+/* An arbitrary initial parameter */
+#define JHASH_INITVAL           0xdeadbeef
+
+#endif /* QEMU_JHASH_H__ */
-- 
1.9.1