Function parse_io_config_address

pci/src/bus.rs:536–552

Parse the CONFIG_ADDRESS register to a (bus, device, function, register) tuple.

(config_address: u32)

// Parse the CONFIG_ADDRESS register to a (bus, device, function, register) tuple.
fn parse_io_config_address(config_address: u32) -> (usize, usize, usize, usize) {
    const BUS_NUMBER_OFFSET: usize = 16;
    const BUS_NUMBER_MASK: u32 = 0x00ff;
    const DEVICE_NUMBER_OFFSET: usize = 11;
    const DEVICE_NUMBER_MASK: u32 = 0x1f;
    const FUNCTION_NUMBER_OFFSET: usize = 8;
    const FUNCTION_NUMBER_MASK: u32 = 0x07;
    const REGISTER_NUMBER_OFFSET: usize = 2;
    const REGISTER_NUMBER_MASK: u32 = 0x3f;

    (
        shift_and_mask(config_address, BUS_NUMBER_OFFSET, BUS_NUMBER_MASK),
        shift_and_mask(config_address, DEVICE_NUMBER_OFFSET, DEVICE_NUMBER_MASK),
        shift_and_mask(config_address, FUNCTION_NUMBER_OFFSET, FUNCTION_NUMBER_MASK),
        shift_and_mask(config_address, REGISTER_NUMBER_OFFSET, REGISTER_NUMBER_MASK),
    )
}

#[cfg(test)]
mod unit_tests {