bitwise shift operators, where does the bit go?

Projects Programming
4 
for(byte i=0;i<8;i++)
{   data >>=1;
   if(overflow) {
       do blah;
   }
}

A right shift cannot create an overflow condition. All you need to do is test the low order bit and shift the data afterwards.

for(byte i=0;i<8;i++)
{
   if(data & 1) {
       do blah;
   }
  data >>= 1;
}

If you need to test the high order bit first this code will work:

for(byte i=0;i<8;i++)
{
   if(data & 0x80) {
       do blah;
   }
  data <<= 1;
}

If data is a signed byte you can use (data < 0) instead of (data & 0x80).

Pete