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__author__ = "Giuseppe Natale"
__copyright__ = "Copyright 2016, Xilinx"
__email__ = "pynq_support@xilinx.com"


from pynq import MMIO
from pynq import PL

class Button(object):
    """This class controls the onboard push-buttons.

    Attributes
    ----------
    index : int
        Index of the push-buttons, starting from 0.
        
    """
    _mmio = None

    def __init__(self, index):
        """Create a new Button object.
        
        Parameters
        ----------
        index : int
            The index of the push-buttons, from 0 to 3.
            
        """
        if Button._mmio is None:
            Button._mmio = MMIO(int(PL.ip_dict["SEG_btns_gpio_Reg"][0],16))
        self.index = index

    def read(self):
        """Read the current value of the button.

        Returns
        -------
        int
            Either 1 if the button is pressed or 0 otherwise
            
        """
        curr_val = Button._mmio.read()
        return (curr_val & (1 << self.index)) >> self.index
