diff --git a/README.md b/README.md
index 22b96b04..ff60a57d 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ mkdir -p bin
 cd src
 
 # e.g. OS X sample
-make build ARCH=x64 COMP=gcc OS=osx
+make pgo-build ARCH=armv8-5a COMP=clang OS=osx
 cd ..
 ./bin/mEdax
 ```
@@ -35,7 +35,7 @@ docker run --name "edax" -v "$(pwd)/:/home/edax/" -it edax
 cd /home/edax/
 mkdir -p bin
 cd src
-make build ARCH=x64 COMP=gcc OS=linux
+make build ARCH=x86-64-v3 COMP=clang OS=linux
 
 cd ..
 curl -OL https://github.com/abulmo/edax-reversi/releases/download/v4.4/eval.7z # e.g. use v4.4 eval.dat
@@ -51,111 +51,21 @@ cd src
 doxygen
 open ../doc/html/index.html
 ```
-=======
-# edax-reversi-AVX
-Automatically exported from code.google.com/p/okuharaandroid-edax-reversi
-
-=======
-# edax-reversi-AVX
-Automatically exported from code.google.com/p/okuharaandroid-edax-reversi
-
-Edax is a strong othello program. Its main features are:
-
-    fast bitboard based & multithreaded engine.
-    accurate midgame-evaluation function.
-    opening book learning capability.
-    text based rich interface.
-    multi-protocol support to connect to graphical interfaces or play on Internet (GGS).
-    multi-OS support to run under MS-Windows, Linux and Mac OS X.
-
->>>>>>> 81dec96 (Kindergarten last flip for arm32; MSVC arm Windows build (not tested))
-This is SSE/AVX optimized version of Edax 4.4.0. Functionally equivalent to the parent project, provided no bugs are introduced.
-
-Thanks to AVX2, x64-modern build solves fforum-40-59.obf 60% faster than official edax-4.4 on Haswell, and runs level 30 autoplay 80% faster.
-
-See http://www.amy.hi-ho.ne.jp/okuhara/bitboard.htm and http://www.amy.hi-ho.ne.jp/okuhara/edaxopt.htm for optimization details in Japanese.
-
-## 1. Mobility (board_sse.c, board_mmx.c)
-
-### 1.1 new SSE2 version of get_moves
-Diagonals are SIMD'd using vertical mirroring by bswap.
-
-    Athlon -get_moves_sse
-    problem\fforum-20-39.obf: 111349635 nodes in 0:07.998 (13922185 nodes/s).
-    mobility: 81.10 < 81.28 +/- 0.17 < 82.03
-    Athlon +get_moves_sse
-    problem\fforum-20-39.obf: 111349635 nodes in 0:07.889 (14114544 nodes/s).
-    mobility: 71.08 < 71.72 +/- 0.34 < 73.53
-    Core2 -get_moves_sse
-    problem/fforum-20-39.obf: 111349635 nodes in 0:10.180 (10938078 nodes/s).
-    mobility: 78.06 < 78.18 +/- 0.08 < 78.41
-    Core2 +get_moves_sse
-    problem/fforum-20-39.obf: 111349635 nodes in 0:09.978 (11159514 nodes/s).
-    mobility: 60.84 < 61.19 +/- 0.13 < 61.47
-
-### 1.2 can_move
-Now calls SIMD'd get_moves for x86/x64 build.
-
-## 2. Stability (board.c, board_sse.c, board_mmx.c)
-
-### 2.1 get_full_lines_h, get_full_lines_v
-get_full_lines for horizontal and vertical are simplified. The latter is compiled into rotation instrunction.
-
-### 2.2 rearranged loop
-The last while loop is rearranged not to call bit_count in case stable == 0.
-
-### 2.3 new SSE2 version with bswap and pcmpeqb
-    Athlon -get_stability_sse
-    stability: 90.10 < 90.28 +/- 0.24 < 91.20
-    Athlon +get_stability_sse
-    stability: 81.59 < 81.93 +/- 0.73 < 86.25
-    Core2 -get_stability_sse
-    stability: 79.24 < 79.39 +/- 0.15 < 79.93
-    Core2 +get_stability_sse
-    stability: 71.80 < 71.85 +/- 0.06 < 72.07
-
-### 2.4 get_corner_stability
-Kindergarten version eliminates bit_count call.
-
-### 2.5 find_edge_stable
-Loop optimization and flip using carry propagation. One time execution but affect total solving time.
-
-## 3. eval.c (4.4.5)
-Eval feature calculation using SSE2 / AVX2 (now in eval_sse.c) improves midgame by 15-30% and endgame by 8-12%.
-Restoring eval from backup instead of rewinding.
-eval_open (one time execution) is also optimized.
-
-## 4. hash.c
-I think hash->data.move[0] on line 677 should be hash->data.move[1].
-
-## 5. board_symetry, board_unique (board.c, board_sse.c)
-SSE optimization and mirroring reduction. (Not used in solving game)
-
-## 6. endgame_sse.c (4.4.7)
-Keep more variables in SSE registers.  SSE optimized count_last_flip.  Parity sort by shuffle.
-
-## 7. board_get_hash_code (4.5.0)
-Changed to use CRC32c.  This enables hardware acceleration on modern build.
-
-## 8. AVX2 versions (x64-modern build only)
-In many cases AVX2 version is simplest, thanks to variable shift instructions (although they are 3 micro-op instructions).
-
-Benchmarks are on Core i5-4260U (Haswell) 1.4GHz (TB 2.7GHz) single thread.
-
-    4.4.0 original x64-modern clang
-    problem/fforum-20-39.obf: 111349635 nodes in 0:05.726 (19446321 nodes/s).
-    +optimizations 1-5 above, no-avx2
-    problem/fforum-20-39.obf: 111349635 nodes in 0:05.342 (20844185 nodes/s).
-    +get_moves (board_sse.c)
-    problem/fforum-20-39.obf: 111349635 nodes in 0:05.142 (21654927 nodes/s).
-    +flip_avx.c
-    problem/fforum-20-39.obf: 111349635 nodes in 0:04.946 (22513068 nodes/s).
-    +count_last_flip_sse.c
-    problem/fforum-20-39.obf: 111349635 nodes in 0:04.906 (22696624 nodes/s).
-
-## 9. makefile
-gcc-old, x86 build should be -m32, not -m64. Some flags and defines added for optimization.
-<<<<<<< HEAD
->>>>>>> b9d48c1 (Create README.md)
-=======
->>>>>>> 81dec96 (Kindergarten last flip for arm32; MSVC arm Windows build (not tested))
+## version 4.6
+version 4.6 is an evolution of version 4.4 that tried to incorporate changes made by Toshihiko Okuhara in version 4.5.3 and :
+ - keep the code encapsulated: I revert many pieces of code from version 4.5.3 with manually inlined code.
+ - remove assembly code (intrinsics are good enough)
+ - make some changes easily reversible with a macro switch (USE_SIMD, USE_SOLID, etc.)
+ - remove buggy code and/or buggy file path.
+ - disable code (#if 0) that I found too slow on my cpu.
+ - make soft CRC32c behave the same as the hardware CRC32c (version 4.5.3 is buggy here).
+ - the code switch from c99 to c17 and use stdatomic.h threads.h (if available) stdalign.h
+ - remove bench.c: most of the functions get optimized out and could not be measured.
+ - support only 64 bit OSes. 
+ - this version is still in development and may change before I release it.
+
+## makefile
+the major change is that the ARCH options are no longer the same, as they are too many possible options to enable avx2, avx512, CRC32c, etc.
+Use make -help for a list of options. 
+
+