+void wxULongLongWx::Divide(const wxULongLongWx& divisorIn,
+ wxULongLongWx& quotient,
+ wxULongLongWx& remainder) const
+{
+ if ((divisorIn.m_lo == 0) && (divisorIn.m_hi == 0))
+ {
+ // provoke division by zero error and silence the compilers warnings
+ // about an expression without effect and unused variable
+ unsigned long dummy = divisorIn.m_lo/divisorIn.m_hi;
+ dummy += 0;
+ }
+
+ // VZ: I'm writing this in a hurry and it's surely not the fastest way to
+ // do this - any improvements are more than welcome
+ //
+ // code inspired by the snippet at
+ // http://www.bearcave.com/software/divide.htm
+ //
+ // Copyright notice:
+ //
+ // Use of this program, for any purpose, is granted the author, Ian
+ // Kaplan, as long as this copyright notice is included in the source
+ // code or any source code derived from this program. The user assumes
+ // all responsibility for using this code.
+
+ // init everything
+ wxULongLongWx dividend = *this,
+ divisor = divisorIn;
+
+ quotient = 0l;
+ remainder = 0l;
+
+ // check for some particular cases
+ if ( divisor > dividend )
+ {
+ remainder = dividend;
+ }
+ else if ( divisor == dividend )
+ {
+ quotient = 1l;
+ }
+ else
+ {
+ // here: dividend > divisor
+ size_t nBits = 64u;
+ wxULongLongWx d;
+
+ #define IS_MSB_SET(ll) ((ll.m_hi) & (1 << (8*sizeof(long) - 1)))
+
+ while ( remainder < divisor )
+ {
+ remainder <<= 1;
+ if ( IS_MSB_SET(dividend) )
+ {
+ remainder |= 1;
+ }
+
+ d = dividend;
+ dividend <<= 1;
+
+ nBits--;
+ }
+
+ // undo the last loop iteration
+ dividend = d;
+ remainder >>= 1;
+ nBits++;
+
+ for ( size_t i = 0; i < nBits; i++ )
+ {
+ remainder <<= 1;
+ if ( IS_MSB_SET(dividend) )
+ {
+ remainder |= 1;
+ }
+
+ wxULongLongWx t = remainder - divisor;
+ dividend <<= 1;
+ quotient <<= 1;
+ if ( !IS_MSB_SET(t) )
+ {
+ quotient |= 1;
+
+ remainder = t;
+ }
+ }
+ }
+}
+
projects / wxWidgets.git / blobdiff