Moved SuperFastHash function from base/hash.cc to base/third_party.

This code was written by Paul Hsieh under a 3-clause BSD license. It
belongs in third_party.

I did not move the existing implementation, but re-downloaded the code
from upstream:
http://www.azillionmonkeys.com/qed/hash.html
This version is formatted differently and is written in plain C, but it
is identical to the version that was previously in hash.cc.

Added LICENSE and README.chromium files, as well as adding license text
to the top of superfasthash.cc, as required by checklicenses.py.

BUG=347393

Review URL: https://codereview.chromium.org/181643004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254437 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 142 insertions, 0 deletions

diff --git a/base/third_party/superfasthash/LICENSE b/base/third_party/superfasthash/LICENSE
new file mode 100644
index 0000000..3c40a3e
--- /dev/null
+++ b/base/third_party/superfasthash/LICENSE
@@ -0,0 +1,27 @@
+Paul Hsieh OLD BSD license
+
+Copyright (c) 2010, Paul Hsieh
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+* Redistributions in binary form must reproduce the above copyright notice, this
+  list of conditions and the following disclaimer in the documentation and/or
+  other materials provided with the distribution.
+* Neither my name, Paul Hsieh, nor the names of any other contributors to the
+  code use may not be used to endorse or promote products derived from this
+  software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/base/third_party/superfasthash/OWNERS b/base/third_party/superfasthash/OWNERS
new file mode 100644
index 0000000..f34cfb1
--- /dev/null
+++ b/base/third_party/superfasthash/OWNERS
@@ -0,0 +1,2 @@
+mgiuca@chromium.org
+rvargas@chromium.org
diff --git a/base/third_party/superfasthash/README.chromium b/base/third_party/superfasthash/README.chromium
new file mode 100644
index 0000000..d41ed77
--- /dev/null
+++ b/base/third_party/superfasthash/README.chromium
@@ -0,0 +1,29 @@
+Name: Paul Hsieh's SuperFastHash
+Short Name: SuperFastHash
+URL: http://www.azillionmonkeys.com/qed/hash.html
+Version: 0
+Date: 2012-02-21
+License: BSD
+License File: LICENSE
+Security Critical: yes
+
+Description:
+A fast string hashing algorithm.
+
+Local Modifications:
+- Added LICENSE.
+- Added license text as a comment to the top of superfasthash.c.
+- #include <stdint.h> instead of "pstdint.h".
+- #include <stdlib.h>.
+
+The license is a standard 3-clause BSD license with the following minor changes:
+
+"nor the names of its contributors may be used"
+is replaced with:
+"nor the names of any other contributors to the code use may not be used"
+
+and
+
+"IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE"
+is replaced with:
+"IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE"
diff --git a/base/third_party/superfasthash/superfasthash.c b/base/third_party/superfasthash/superfasthash.c
new file mode 100644
index 0000000..6e7687e
--- /dev/null
+++ b/base/third_party/superfasthash/superfasthash.c
@@ -0,0 +1,84 @@
+// Copyright (c) 2010, Paul Hsieh
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice, this
+//   list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither my name, Paul Hsieh, nor the names of any other contributors to the
+//   code use may not be used to endorse or promote products derived from this
+//   software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+#include <stdint.h>
+#include <stdlib.h>
+#undef get16bits
+#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
+  || defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
+#define get16bits(d) (*((const uint16_t *) (d)))
+#endif
+
+#if !defined (get16bits)
+#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+                       +(uint32_t)(((const uint8_t *)(d))[0]) )
+#endif
+
+uint32_t SuperFastHash (const char * data, int len) {
+uint32_t hash = len, tmp;
+int rem;
+
+    if (len <= 0 || data == NULL) return 0;
+
+    rem = len & 3;
+    len >>= 2;
+
+    /* Main loop */
+    for (;len > 0; len--) {
+        hash  += get16bits (data);
+        tmp    = (get16bits (data+2) << 11) ^ hash;
+        hash   = (hash << 16) ^ tmp;
+        data  += 2*sizeof (uint16_t);
+        hash  += hash >> 11;
+    }
+
+    /* Handle end cases */
+    switch (rem) {
+        case 3: hash += get16bits (data);
+                hash ^= hash << 16;
+                hash ^= ((signed char)data[sizeof (uint16_t)]) << 18;
+                hash += hash >> 11;
+                break;
+        case 2: hash += get16bits (data);
+                hash ^= hash << 11;
+                hash += hash >> 17;
+                break;
+        case 1: hash += (signed char)*data;
+                hash ^= hash << 10;
+                hash += hash >> 1;
+    }
+
+    /* Force "avalanching" of final 127 bits */
+    hash ^= hash << 3;
+    hash += hash >> 5;
+    hash ^= hash << 4;
+    hash += hash >> 17;
+    hash ^= hash << 25;
+    hash += hash >> 6;
+
+    return hash;
+}