X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Fcore%2Fhash.cpp;fp=source%2Fcore%2Fhash.cpp;h=26e60592618e9e15847927e51e9dfec8626b6bd6;hb=cf20196055ed5074c448a16144c47b7e8a32c6a8;hp=0000000000000000000000000000000000000000;hpb=928694ff233bd4383f30b05bf6d2d37562b77a9a;p=libs%2Fcore.git

diff --git a/source/core/hash.cpp b/source/core/hash.cpp
new file mode 100644
index 0000000..26e6059
--- /dev/null
+++ b/source/core/hash.cpp
@@ -0,0 +1,49 @@
+#include <stdexcept>
+#include "hash.h"
+
+using namespace std;
+
+namespace Msp {
+
+/*
+http://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function
+http://www.isthe.com/chongo/tech/comp/fnv/index.html
+*/
+
+unsigned hash32(const void *data, unsigned size, unsigned bits)
+{
+	if(bits==0 || bits>32)
+		throw invalid_argument("hash32");
+
+	static const unsigned prime = 16777619;
+	static const unsigned offset = 2166136261U;
+
+	unsigned result = offset;
+	for(unsigned i=0; i<size; ++i)
+		result = (result^*(reinterpret_cast<const unsigned char *>(data)+i))*prime;
+
+	if(bits<32)
+		result = (result>>bits ^ result) & ((1<<bits)-1);
+
+	return result;
+}
+
+HashValue64 hash64(const void *data, unsigned size, unsigned bits)
+{
+	if(bits==0 || bits>64)
+		throw invalid_argument("hash64");
+
+	static const HashValue64 prime = 1099511628211ULL;
+	static const HashValue64 offset = 14695981039346656037ULL;
+
+	HashValue64 result = offset;
+	for(unsigned i=0; i<size; ++i)
+		result = (result^*(reinterpret_cast<const unsigned char *>(data)+i))*prime;
+
+	if(bits<64)
+		result = (result>>bits ^ result) & ((1ULL<<bits)-1);
+
+	return result;
+}
+
+} // namespace Msp