MOAB: Mesh Oriented datABase  (version 5.2.1)
SysUtil.hpp
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00001 #ifndef MB_SYS_UTIL_HPP
00002 #define MB_SYS_UTIL_HPP
00003 
00004 #include <string.h>  // for size_t
00005 #include <stdio.h>
00006 #include <iosfwd>
00007 
00008 namespace moab
00009 {
00010 
00011 namespace SysUtil
00012 {
00013 
00014     /**\brief Similar to memset, but accepts values larger than 1 char
00015      *
00016      * Set block of memory to repeating copies of a sequene of bytes.
00017      *\param mem   Pointer to start of memory block to initialize
00018      *\param value Byte sequence to initialize mem with
00019      *\param value_size Size of 'value'
00020      *\param num_elem Size of 'mem' as a multiple of value_size (the number of
00021      *             copies of 'value' to write into 'mem'.)
00022      */
00023     void setmem( void* mem, const void* value, unsigned value_size, size_t num_elem );
00024 
00025     /**\brief Get size of file (if it is a regular file)
00026      *
00027      * Get size of regular file.
00028      *\return - file size if known
00029      *        - -1 if file size cannot be determined (e.g. a pipe)
00030      *        - -2 if an unexpected failure occured (may indicate change
00031      *           in file position.)
00032      */
00033     long filesize( FILE* filp );
00034 
00035     /**\brief Get size of file (if it is a regular file)
00036      *
00037      * Get size of regular file.
00038      *\return - file size if known
00039      *        - -1 if file size cannot be determined (e.g. a pipe)
00040      *        - -2 if an unexpected failure occured (may indicate change
00041      *           in file position.)
00042      */
00043     long filesize( std::ifstream& str );
00044 
00045     /**\brief Check if platform is little-endian
00046      *
00047      * Check if platform is little-endian (least significant
00048      * byte at highest memory address.)
00049      */
00050     inline bool little_endian()
00051     {
00052         const unsigned one = 1;
00053         return !*( (char*)&one );
00054     }
00055 
00056     /**\brief Check if platform is big-endian
00057      *
00058      * Check if platform is big-endian (least significant
00059      * byte at lowest memory address.)
00060      */
00061     inline bool big_endian()
00062     {
00063         const unsigned one = 1;
00064         return !( ( (char*)&one )[sizeof( unsigned ) - 1] );
00065     }
00066 
00067     /**\brief Swap byte order (e.g. change from big-endian to little-endian)
00068      *
00069      * Reverse byte order or array of values.
00070      *\param data        Pointer to beginning of memory block to modify
00071      *\param values_size Size of one value
00072      *\param num_elem    Number of values of size 'value_size' in 'data'
00073      */
00074     void byteswap( void* data, unsigned value_size, size_t num_elem );
00075 
00076     /**\brief Alternate byteswap optimized for 2-byte values */
00077     void byteswap2( void* data, size_t num_elem );
00078     /**\brief Alternate byteswap optimized for 4-byte values */
00079     void byteswap4( void* data, size_t num_elem );
00080     /**\brief Alternate byteswap optimized for 8-byte values */
00081     void byteswap8( void* data, size_t num_elem );
00082 
00083     /**\brief Type-specific byte swap */
00084     template < typename T >
00085     inline void byteswap( T* data, size_t num_elem )
00086     {
00087         switch( sizeof( T ) )
00088         {
00089             case 1:
00090                 break;
00091             case 2:
00092                 byteswap2( data, num_elem );
00093                 break;
00094             case 4:
00095                 byteswap4( data, num_elem );
00096                 break;
00097             case 8:
00098                 byteswap8( data, num_elem );
00099                 break;
00100             default:
00101                 byteswap( data, sizeof( T ), num_elem );
00102                 break;
00103         }
00104     }
00105 
00106 }  // namespace SysUtil
00107 
00108 }  // namespace moab
00109 
00110 #endif
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