st.c: fix st_hash* functions [Bug #13019]

Previous implementation had an issues:
- macros murmur1 assumes murmur_step takes rotation value
  as a second argument
- but murmur_step second argument is "next block"
- this makes st_hash_uint and st_hash_end to not mix high bits of
  hash value into lower bits
- this leads to pure hash behavior on doubles and mixing hashes using
  st_hash_uint.
  It didn't matter when bins amount were prime numbers, but it hurts
  when bins are powers of two.

Mistake were created cause of attempt to co-exist Murmur1 and Murmur2
in a same code.

Change it to single hash-function implementation.
- block function is in a spirit of Murmur functions,
  but handles inter-block dependency a bit better (imho).
- final block is read in bit more optimal way on CPU with unaligned word access,
- final block is mixed in simple way,
- finalizer is taken from MurmurHash3 (it makes most of magic :) )
  (64bit finalizer is taken from
  http://zimbry.blogspot.ru/2011/09/better-bit-mixing-improving-on.html)

Also remove ST_USE_FNV1: it lacks implementation of many functions,
and looks to be abandoned

Author: Sokolov Yura aka funny_falcon <funny.falcon@gmail.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 0 deletions

diff --git a/include/ruby/st.h b/include/ruby/st.h
index 41f2913b80..47e14a3e2c 100644
--- a/include/ruby/st.h
+++ b/include/ruby/st.h
@@ -63,6 +63,8 @@ struct st_hash_type {
     st_index_t (*hash)(ANYARGS /*st_data_t*/);        /* st_hash_func* */
 };
 
+#define ST_INDEX_BITS (SIZEOF_ST_INDEX_T * CHAR_BIT)
+
 #if defined(HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR) && defined(HAVE_BUILTIN___BUILTIN_TYPES_COMPATIBLE_P)
 # define ST_DATA_COMPATIBLE_P(type) \
    __builtin_choose_expr(__builtin_types_compatible_p(type, st_data_t), 1, 0)