Adding upstream version 6.0.4-dfsg.upstream/6.0.4-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 112 insertions, 0 deletions

diff --git a/src/VBox/Runtime/include/internal/strhash.h b/src/VBox/Runtime/include/internal/strhash.h
new file mode 100644
index 00000000..c224a6e3
--- /dev/null
+++ b/src/VBox/Runtime/include/internal/strhash.h
@@ -0,0 +1,112 @@
+/* $Id: strhash.h $ */
+/** @file
+ * IPRT - Internal header containing inline string hashing functions.
+ */
+
+/*
+ * Copyright (C) 2006-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_INTERNAL_strhash_h
+#define IPRT_INCLUDED_INTERNAL_strhash_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+
+
+/* sdbm:
+   This algorithm was created for sdbm (a public-domain reimplementation of
+   ndbm) database library. it was found to do well in scrambling bits,
+   causing better distribution of the keys and fewer splits. it also happens
+   to be a good general hashing function with good distribution. the actual
+   function is hash(i) = hash(i - 1) * 65599 + str[i]; what is included below
+   is the faster version used in gawk. [there is even a faster, duff-device
+   version] the magic constant 65599 was picked out of thin air while
+   experimenting with different constants, and turns out to be a prime.
+   this is one of the algorithms used in berkeley db (see sleepycat) and
+   elsewhere. */
+
+/**
+ * Hash string, return hash + length.
+ */
+DECLINLINE(uint32_t) sdbm(const char *str, size_t *pcch)
+{
+    uint8_t *pu8 = (uint8_t *)str;
+    uint32_t hash = 0;
+    int c;
+
+    while ((c = *pu8++))
+        hash = c + (hash << 6) + (hash << 16) - hash;
+
+    *pcch = (uintptr_t)pu8 - (uintptr_t)str - 1;
+    return hash;
+}
+
+
+/**
+ * Hash up to N bytes, return hash + hashed length.
+ */
+DECLINLINE(uint32_t) sdbmN(const char *str, size_t cchMax, size_t *pcch)
+{
+    uint8_t *pu8 = (uint8_t *)str;
+    uint32_t hash = 0;
+    int c;
+
+    while ((c = *pu8++) && cchMax-- > 0)
+        hash = c + (hash << 6) + (hash << 16) - hash;
+
+    *pcch = (uintptr_t)pu8 - (uintptr_t)str - 1;
+    return hash;
+}
+
+
+/**
+ * Incremental hashing.
+ */
+DECLINLINE(uint32_t) sdbmInc(const char *str, uint32_t hash)
+{
+    uint8_t *pu8 = (uint8_t *)str;
+    int c;
+
+    while ((c = *pu8++))
+        hash = c + (hash << 6) + (hash << 16) - hash;
+
+    return hash;
+}
+
+/**
+ * Incremental hashing with length limitation.
+ */
+DECLINLINE(uint32_t) sdbmIncN(const char *psz, size_t cchMax, uint32_t uHash)
+{
+    uint8_t *pu8 = (uint8_t *)psz;
+    int      c;
+
+    while ((c = *pu8++) && cchMax-- > 0)
+        uHash = c + (uHash << 6) + (uHash << 16) - uHash;
+
+    return uHash;
+}
+
+
+#endif /* !IPRT_INCLUDED_INTERNAL_strhash_h */
+