workspace/ksplash/ksplashx/qglobal.cpp

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  43
  44 #include "qglobal.h"
  45
  46 static bool si_alreadyDone = false;
  47 static int  si_wordSize;
  48 static bool si_bigEndian;
  49
  50 /*!
  51     \relates QApplication
  52
  53     Obtains information about the system.
  54
  55     The system's word size in bits (typically 32) is returned in \a
  56     *wordSize. The \a *bigEndian is set to TRUE if this is a big-endian
  57     machine, or to FALSE if this is a little-endian machine.
  58
  59     In debug mode, this function calls qFatal() with a message if the
  60     computer is truly weird (i.e. different endianness for 16 bit and
  61     32 bit integers); in release mode it returns FALSE.
  62 */
  63
  64 bool qSysInfo( int *wordSize, bool *bigEndian )
  65 {
  66 #if defined(QT_CHECK_NULL)
  67     Q_ASSERT( wordSize != 0 );
  68     Q_ASSERT( bigEndian != 0 );
  69 #endif
  70
  71     if ( si_alreadyDone ) {                     // run it only once
  72         *wordSize  = si_wordSize;
  73         *bigEndian = si_bigEndian;
  74         return true;
  75     }
  76
  77     si_wordSize = 0;
  78     Q_ULONG n = (Q_ULONG)(~0);
  79     while ( n ) {                               // detect word size
  80         si_wordSize++;
  81         n /= 2;
  82     }
  83     *wordSize = si_wordSize;
  84
  85     if ( *wordSize != 64 &&
  86          *wordSize != 32 &&
  87          *wordSize != 16 ) {                    // word size: 16, 32 or 64
  88 #if defined(QT_CHECK_RANGE)
  89         qFatal( "qSysInfo: Unsupported system word size %d", *wordSize );
  90 #endif
  91         return false;
  92     }
  93     if ( sizeof(Q_INT8) != 1 || sizeof(Q_INT16) != 2 || sizeof(Q_INT32) != 4 ||
  94          sizeof(Q_ULONG)*8 != si_wordSize || sizeof(float) != 4 || sizeof(double) != 8 ) {
  95 #if defined(QT_CHECK_RANGE)
  96         qFatal( "qSysInfo: Unsupported system data type size" );
  97 #endif
  98         return false;
  99     }
 100
 101     bool  be16, be32;                           // determine byte ordering
 102     short ns = 0x1234;
 103     int   nl = 0x12345678;
 104
 105     unsigned char *p = (unsigned char *)(&ns);  // 16-bit integer
 106     be16 = *p == 0x12;
 107
 108     p = (unsigned char *)(&nl);                 // 32-bit integer
 109     if ( p[0] == 0x12 && p[1] == 0x34 && p[2] == 0x56 && p[3] == 0x78 )
 110         be32 = true;
 111     else
 112     if ( p[0] == 0x78 && p[1] == 0x56 && p[2] == 0x34 && p[3] == 0x12 )
 113         be32 = false;
 114     else
 115         be32 = !be16;
 116
 117     if ( be16 != be32 ) {                       // strange machine!
 118 #if defined(QT_CHECK_RANGE)
 119         qFatal( "qSysInfo: Inconsistent system byte order" );
 120 #endif
 121         return false;
 122     }
 123
 124     *bigEndian = si_bigEndian = be32;
 125     si_alreadyDone = true;
 126     return true;
 127 }