fix errors on running with no SIMD

Author: taqu

.travis.yml

@@ -25,7 +25,7 @@ before_script:
   - tar jxvf cantrbry.tar.bz2
   - mkdir build
   - cd build
-  - cmake ..
+  - cmake .. -DUSE_SIMD=1
 script:
   - make
   - ./TestRangeCoder

README.md

@@ -56,5 +56,15 @@ An implementaion of adaptive range coder for C++
 |sum|0.491946|88|112|
 |xargs.1|0.628815|13|15|
 
+# Building
+For Visual Studio 15 2017,
+```
+git clone https://github.com/taqu/cpprcoder.git
+cd cpprcoder/test
+mkdir build_simd
+pushd build_simd
+cmake -G"Visual Studio 15 2017 Win64" -DUSE_SIMD=1 ..
+```
+
 # License
 This is free and unencumbered software released into the public domain.

cpprcoder.h

@@ -117,7 +117,6 @@ namespace cpprcoder
 #define CPPRCODER_USE_SSE2 (1)
 #endif
 
-
     enum Status
     {
         Status_Success = 0,
@@ -684,6 +683,7 @@ namespace cpprcoder
             frequencies_[i] = 1;
         }
 
+        prefix_[0] = CHUNK_SIZE;
         for(s32 i=1; i<CHUNKS; ++i){
             prefix_[i] = prefix_[i-1] + CHUNK_SIZE;
         }

test/CMakeLists.txt

@@ -22,8 +22,13 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE "${OUTPUT_DIRECTORY}")
 
 add_executable(${ProjectName} ${FILES})
 
+set(CXX_FLAGS_SIMD "")
 if(MSVC)
-    set(DEFAULT_CXX_FLAGS "/DWIN32 /D_WINDOWS /D_MBCS /W4 /WX- /nologo /fp:precise /arch:AVX /Zc:wchar_t /TP /Gd")
+    if(USE_SIMD)
+        set(CXX_FLAGS_SIMD "/arch:AVX")
+    endif()
+
+    set(DEFAULT_CXX_FLAGS "/DWIN32 /D_WINDOWS /D_MBCS /W4 /WX- /nologo /fp:precise /Zc:wchar_t /TP /Gd ${CXX_FLAGS_SIMD}")
     if("1800" VERSION_LESS MSVC_VERSION)
         set(DEFAULT_CXX_FLAGS "${DEFAULT_CXX_FLAGS} /EHsc")
     endif()
@@ -35,7 +40,10 @@ if(MSVC)
     target_link_libraries(${ProjectName} "liblz4_static.lib")
 
 elseif(UNIX)
-    set(DEFAULT_CXX_FLAGS "-Wall -O2 -std=c++11 -march=native")
+    if(USE_SIMD)
+        set(CXX_FLAGS_SIMD "-march=native")
+    endif()
+    set(DEFAULT_CXX_FLAGS "-Wall -O2 -std=c++11 ${CXX_FLAGS_SIMD}")
     set(CMAKE_CXX_FLAGS "${DEFAULT_CXX_FLAGS}")
     target_link_libraries(${ProjectName} "z")
 elseif(APPLE)