file: filter.cc


/*
   This file contains the longer methods for the filter class 
   declared in filter.h.  The methods included are:
   
   constructor:
   filter::filter(unsigned short int newmask,const vector<unsigned short int>&         //OVERLOAD CALL: filter: filter.cc(filter), filter.h(filter)
	       newfields)

   unsigned short int filter::args(const vector<unsigned short int>& args) const                 -filters arguments as unsigned short ints into opcodes.
 
   void filter::printstate() const  -prints out state of filter

   Revision History:
   first made: 3/4/96 by John Langford
*/

#include "filter.h"

/*
  filter(unsigned short int newmask,const vector<unsigned short int>&         //OVERLOAD CALL: filter: filter.cc(filter), filter.h(filter)
	       newfields)
  
  Description:      Constructs the argument to opcode filter.  The object will
                    output an object code with the bits in newmask bitwise 
		    'or'ed with the various arguments.

  Arguments:         newmask  - the instruction bits of an opcode.
                     newfields - a vector of bit locations just past the high
		                 bit of each argument field.

   Return Value:     None.

   Inputs:           None.
   Outputs:          None.

   Error Handling:   error object

   Algorithms:       None.
   Data Structures:  None.

   Last Modified:    3/4/97
*/
filter::filter(unsigned short int newmask,const vector<unsigned short int>& 
	       newfields)
{
  if (newmask > maxbitfield)
    mask=err(OVERSIZE_MASK,newfields,newmask);
  mask=newmask;

  //check that bitfields don't overlap
  for(vector<unsigned short int>::const_iterator i=newfields.begin();
      i!=newfields.end();i++)
    {
      if ((unsigned short int)1 << (*i) > maxbitfield)
	err(OVERSIZE_FIELD,newfields,*i);
    }
  fields=newfields;
}

/*
  inline void filter::printstate() const
  
  Description:      Prints out the state of the filter in a human readable form

  Arguments:         none.

   Return Value:     none.

   Inputs:           None.
   Outputs:          the base instruction bitfield as 0's and 1's followed by 
                     the bit 1 past high of each argument field.

   Error Handling:   None.

   Algorithms:       None.
   Data Structures:  None.

   Last Modified:    3/4/97
*/
struct foo : unary_function<unsigned short int, int>{
};
void foo::operator() (const unsigned short int& p) 
{
  cout << "high = " << p << endl;
}

void filter::printstate() const
{
  cout << hex << mask << dec << endl;
  for (int i=maxbitfield/2;i>0;i/=2)
    if (((mask/i)%2)==1)
      cout << "1";
    else
      cout << "0";
  cout << endl;
  for_each(fields.begin(),
	     fields.end(),
	     foo());
}

/*
  args(const vector<unsigned short int>& args)
  
  Description:      This is the actual filter.  It takes a vector of args, and
                    bitwise 'or's them at the appropriate locations in the 
		    opcode.

  Arguments:         args -a vector of the arguments as unsigned short ints.

   Return Value:     unsigned short int - the instruction bits 'or'ed with the
                      arguments.

   Inputs:           None.
   Outputs:          None.

   Error Handling:   error object

   Algorithms:       None.
   Data Structures:  None.

   Last Modified:    3/4/97
*/
unsigned short int filter::args(const vector<unsigned short int>& args) const
{
  unsigned short int ret=mask;
  if (args.size()!=fields.size()){
    return err(WRONG_ARGUMENT_COUNT,args,ret);
  }
  vector<unsigned short int>::const_iterator i=fields.begin();
  for(int fnum=0;i!=fields.end();i++,fnum++)
    {
      unsigned short int low;
      if((i+1)!=fields.end())
	low=(*(i+1));
      else
	low=0;
      if ((((unsigned short int)1 << ((*i)-low-1))) < args[fnum]){
	
	return err(OVERSIZE_ARGUMENT, args, args[fnum]);
      }
      else
	ret = ret | (args[fnum] << low);
    }
  return ret;
}



Back to Source File Index


C++ to HTML Conversion by ctoohtml