hi,

here is some alternative code called abhisheks method ;). here i assumed that contiguous bits are used as counter bits in increasing order.

'const1' has a '1' at LSB position. rest of the bits are '0's. 'const2' has '1's at the all counter bit positions and rest of the bits are zeros.

mov a,p0
add a,#const1
xrl a,p0
anl a,#const2
xrl p0,a

any comments. or flaws.

abhishek