Change std::ifStream to FileStream of using mmap.

src/FileStream/FileStream.cpp

@@ -0,0 +1,103 @@
+#include "FileStream.h"
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#ifdef WIN32
+#else
+#include <unistd.h>
+#include <sys/mman.h>
+#endif
+
+namespace
+{
+    const unsigned long long SKIP_UNIT_SIZE = 2147483647;//maxValue of int
+}
+
+FileStream::FileStream()
+#ifdef WIN32
+    : mStream()
+#else
+    : mPosition(0)
+    , mData(nullptr)
+    , mFd()
+    , mStSize()
+#endif
+{
+
+}
+
+FileStream::~FileStream()
+{
+
+}
+
+bool FileStream::open(const std::string& aFileName)
+{
+#ifdef WIN32
+    mStream.open(aFileName.c_str(), std::ios_base::binary | std::ios::in);
+    return true;
+#else
+    if ((mFd = ::open(aFileName.c_str(), O_RDONLY)) < 0)
+    {
+        return false;
+    }
+    struct stat sb;
+    if (fstat(mFd, &sb) == -1)
+    {
+        return false;
+    }
+    mStSize = sb.st_size;
+    mData = (int16_t*)mmap(NULL, mStSize, PROT_READ, MAP_SHARED, mFd, 0);
+    return true;
+#endif
+}
+
+void FileStream::seekg(unsigned long long aSkipSize, StreamPosition aFlag)
+{
+#ifdef WIN32
+    if(aFlag == StreamPosition::cur)
+    {
+        unsigned long long skipData = aSkipSize % SKIP_UNIT_SIZE;
+        int skipLoop = static_cast<int>((aSkipSize - skipData) / SKIP_UNIT_SIZE);
+        for(int i = 0;i < skipLoop ; ++i)
+        {
+            mStream.seekg(SKIP_UNIT_SIZE,std::ios::cur);
+        }
+        mStream.seekg(static_cast<int>(skipData),std::ios::cur);
+    }
+    else if(aFlag == StreamPosition::begin)
+    {
+        mStream.seekg(static_cast<int>(aSkipSize),std::ios::beg);
+    }
+#else
+    if(aFlag == StreamPosition::cur)
+    {
+        mPosition += aSkipSize;
+    }
+    else if(aFlag == StreamPosition::begin)
+    {
+        mPosition = aSkipSize;
+    }
+#endif
+}
+
+void FileStream::read(int16_t& aValue)
+{
+#ifdef WIN32
+    mStream.read((char*)&aValue,sizeof(int16_t));
+#else
+    aValue = mData[mPosition/2];
+    mPosition += 2;
+#endif
+}
+
+void FileStream::close()
+{
+#ifdef WIN32
+    mStream.close();
+#else
+    munmap(mData, mStSize);
+    ::close(mFd);
+#endif
+}
+