PIC Assembler Bitwise Operator Left Shift
The operand of the PIC instruction is evaluated to a constant at assembly time- the code emitted will contain a constant in that position. For example: 


  movlw    ~(1&lt;&lt;1) ; set GP1 as an output


1 &lt;&lt; 1 is evaluated as  b'00000010' (b'00000001' left-shifted by 1 - it is understood that a 0 is shifted in)

The the complement is applied (all 8 bits are flipped), so you get 

b'11111101' 

and the code emitted  is  

movlw   b'11111101' 

It's the same as directly writing the above except you might find it more readable to write it in the way shown.