Cleanup: Move xxhash32 code to libutil

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

2 files changed, 104 insertions, 0 deletions

diff --git a/lib/util/Makemodule.am b/lib/util/Makemodule.am
index 87f3495..5cff2dd 100644
--- a/lib/util/Makemodule.am
+++ b/lib/util/Makemodule.am
@@ -1,6 +1,7 @@
 libutil_a_SOURCES = include/util.h include/str_table.h
 libutil_a_SOURCES += lib/util/str_table.c lib/util/alloc.c
 libutil_a_SOURCES += lib/util/rbtree.c include/rbtree.h
+libutil_a_SOURCES += lib/util/xxhash.c
 libutil_a_CFLAGS = $(AM_CFLAGS)
 libutil_a_CPPFLAGS = $(AM_CPPFLAGS)
 
diff --git a/lib/util/xxhash.c b/lib/util/xxhash.c
new file mode 100644
index 0000000..4e1e0e0
--- /dev/null
+++ b/lib/util/xxhash.c
@@ -0,0 +1,103 @@
+/*
+ * xxHash - Extremely Fast Hash algorithm
+ * Copyright (C) 2012-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * 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.
+ *
+ * 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.
+ * ----------------------------------------------------------------------------
+ * This code has been lifted from Linux (the OS kernel) and adapted for use in
+ * libsquashfs. For the original, unmodified and complete source, see below.
+ *
+ * You can contact the author at:
+ * - xxHash homepage: http://cyan4973.github.io/xxHash/
+ * - xxHash source repository: https://github.com/Cyan4973/xxHash
+ */
+#include "config.h"
+#include "util.h"
+
+#define xxh_rotl32(x, r) ((x << r) | (x >> (32 - r)))
+
+static const sqfs_u32 PRIME32_1 = 2654435761U;
+static const sqfs_u32 PRIME32_2 = 2246822519U;
+static const sqfs_u32 PRIME32_3 = 3266489917U;
+static const sqfs_u32 PRIME32_4 =  668265263U;
+static const sqfs_u32 PRIME32_5 =  374761393U;
+
+static sqfs_u32 xxh32_round(sqfs_u32 seed, sqfs_u32 input)
+{
+	seed += input * PRIME32_2;
+	seed = xxh_rotl32(seed, 13);
+	seed *= PRIME32_1;
+	return seed;
+}
+
+sqfs_u32 xxh32(const void *input, const size_t len)
+{
+	const sqfs_u8 *p = (const sqfs_u8 *)input;
+	const sqfs_u8 *b_end = p + len;
+	sqfs_u32 h32;
+
+	if (len >= 16) {
+		const sqfs_u8 *const limit = b_end - 16;
+		sqfs_u32 v1 = PRIME32_1 + PRIME32_2;
+		sqfs_u32 v2 = PRIME32_2;
+		sqfs_u32 v3 = 0;
+		sqfs_u32 v4 = PRIME32_1;
+
+		do {
+			v1 = xxh32_round(v1, ((sqfs_u32 *)p)[0]);
+			v2 = xxh32_round(v2, ((sqfs_u32 *)p)[1]);
+			v3 = xxh32_round(v3, ((sqfs_u32 *)p)[2]);
+			v4 = xxh32_round(v4, ((sqfs_u32 *)p)[3]);
+			p += 16;
+		} while (p <= limit);
+
+		h32 = xxh_rotl32(v1, 1) + xxh_rotl32(v2, 7) +
+			xxh_rotl32(v3, 12) + xxh_rotl32(v4, 18);
+	} else {
+		h32 = PRIME32_5;
+	}
+
+	h32 += (sqfs_u32)len;
+
+	while (p + 4 <= b_end) {
+		h32 += (*((sqfs_u32 *)p)) * PRIME32_3;
+		h32 = xxh_rotl32(h32, 17) * PRIME32_4;
+		p += 4;
+	}
+
+	while (p < b_end) {
+		h32 += (*p) * PRIME32_5;
+		h32 = xxh_rotl32(h32, 11) * PRIME32_1;
+		p++;
+	}
+
+	h32 ^= h32 >> 15;
+	h32 *= PRIME32_2;
+	h32 ^= h32 >> 13;
+	h32 *= PRIME32_3;
+	h32 ^= h32 >> 16;
+	return h32;
+}