matrix_rhal 0.0.4

use super::config::State;
use super::Gpio;
use crate::bus::memory_map::*;

impl<'a> Gpio<'a> {
    /// Returns the current digital value of a MATRIX GPIO pin (0->15).
    pub fn get_state(&self, pin: u8) -> bool {
        // TODO: add error check
        Gpio::is_pin_valid(pin).unwrap();

        // create read buffer
        let mut data: [u32; 3] = [0; 3];

        // update read buffer
        self.pin_get(&mut data, 2, 1); // all pin states are encoded as a single u16. 2 bytes needed (8*2 = 16 pins)

        // bit operation to extract the current pin's state
        let mask = 0x1 << pin;
        let state = (data[2] & mask) >> pin;

        match state {
            0 => false,
            1 => true,
            _ => {
                panic!("Error retrieving current pin state. Digital value returned was not 0 or 1")
            }
        }
    }

    // TODO: change u8 to State
    /// Returns the current digital value of every MATRIX GPIO pin (0->15)
    pub fn get_states(&self) -> [bool; 16] {
        // create read buffer
        let mut data: [u32; 3] = [0; 3];

        // update read buffer
        self.pin_get(&mut data, 2, 1); // all pin states are encoded as a single u16. 2 bytes needed (8*2 = 16 pins)

        // bit operation to extract each pin state (0-15)
        let mut pins: [bool; 16] = [false; 16];
        for i in 0..16 {
            let mask = 0x1 << i;
            let state = ((data[2] & mask) >> i) as u8;

            pins[i] = match state {
                0 => false,
                1 => true,
                _ => panic!(
                    "Error retrieving current pin state. Digital value returned was not 0 or 1"
                ),
            };
        }

        pins
    }

    /// Shortener to populate a read buffer for GPIO pin information.
    fn pin_get(&self, buffer: &mut [u32], buffer_length: u32, address_offset: u16) {
        // address to query
        buffer[0] = (fpga_address::GPIO + address_offset) as u32;
        // size of expected data (bytes)
        buffer[1] = buffer_length;

        // populate buffer
        // the buffer will be passed a value that contains the state of each GPIO pin
        self.bus
            .read(unsafe { std::mem::transmute::<&mut [u32], &mut [u8]>(buffer) });
    }
}