def ldrpc_source_address(line):
    """Calculate the absolute source address of a PC-relative load.

    'line' is a line returned by disassembly_lines().
    If it doesn't look like the right kind of instruction, returns None.
    """    
    # Example:  ldr r2, [pc, #900]  ; (0x000034b4)
    if line.op == 'ldr' and line.args.find('[pc') > 0:
        return int(line.comment.strip(';( )'), 0)