Changeset 5ae8168 in mainline

Timestamp:

2018-07-05T21:41:21Z (7 years ago)

Author:

Dzejrou <dzejrou@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

b9076db

Parents:

e912cdf

git-author:

Dzejrou <dzejrou@…> (2018-04-25 17:38:07)

git-committer:

Dzejrou <dzejrou@…> (2018-07-05 21:41:21)

Message:

cpp: changed hash to be identity for integral and fp values

File:

• uspace/lib/cpp/include/impl/functional.hpp (modified) (1 diff)

uspace/lib/cpp/include/impl/functional.hpp

@@ -727 +727 @@
         T hash_(uint64_t x) noexcept
         {
-            // TODO: This is copied form adt/hash (temporarily),
-            //       check if we can use something better.
-            x = (x ^ 61) ^ (x >> 16);
-            x = x + (x << 3);
-            x = x ^ (x >> 4);
-            x = x * 0x27d4eb2d;
-            x = x ^ (x >> 15);
-
-            return static_cast<T>((x << 32) | (x >> 32));
+            /**
+             * Note: std::hash is used for indexing in
+             *       unordered containers, not for cryptography.
+             *       Because of this, we decided to simply convert
+             *       the value to uin64_t, which will help us
+             *       with testing (since in order to create
+             *       a collision in a multiset or multimap
+             *       we simply need 2 values that congruent
+             *       by the size of the table.
+             */
+            return static_cast<T>(x);
         }