Method read

plugins/e57/libE57Format/src/CheckedFile.cpp:309–373

}

void CheckedFile::read( char *buf, size_t nRead, size_t /*bufSize*/ )
{
   //??? what if read past logical end?, or physical end?
   //??? need to keep track of logical length?
   //??? check bufSize OK

   const uint64_t end = position( Logical ) + nRead;
   const uint64_t logicalLength = length( Logical );

   if ( end > logicalLength )
   {
      throw E57_EXCEPTION2( ErrorInternal, "fileName=" + fileName_ + " end=" + toString( end ) +
                                              " length=" + toString( logicalLength ) );
   }

   uint64_t page = 0;
   size_t pageOffset = 0;

   getCurrentPageAndOffset( page, pageOffset );

   size_t n = std::min( nRead, logicalPageSize - pageOffset );

   // Allocate temp page buffer
   std::vector<char> page_buffer_v( physicalPageSize );
   char *page_buffer = page_buffer_v.data();

   while ( nRead > 0 )
   {
      readPhysicalPage( page_buffer, page );

      switch ( checkSumPolicy_ )
      {
         case ChecksumPolicy::ChecksumNone:
            break;

         case ChecksumPolicy::ChecksumAll:
            verifyChecksum( page_buffer, page );
            break;

         default:
         {
            const auto checksumMod =
               static_cast<unsigned int>( std::nearbyint( 100.0 / checkSumPolicy_ ) );

            if ( !( page % checksumMod ) || ( nRead < physicalPageSize ) )
            {
               verifyChecksum( page_buffer, page );
            }
         }
         break;
      }

      memcpy( buf, page_buffer + pageOffset, n );

      buf += n;
      nRead -= n;
      pageOffset = 0;
      ++page;