// +build avr

package interrupt

import "device"

// State represents the previous global interrupt state.
type State uint8

// Disable disables all interrupts and returns the previous interrupt state. It
// can be used in a critical section like this:
//
//     state := interrupt.Disable()
//     // critical section
//     interrupt.Restore(state)
//
// Critical sections can be nested. Make sure to call Restore in the same order
// as you called Disable (this happens naturally with the pattern above).
func Disable() (state State) {
	// SREG is at I/O address 0x3f.
	return State(device.AsmFull(`
		in {}, 0x3f
		cli
	`, nil))
}

// Restore restores interrupts to what they were before. Give the previous state
// returned by Disable as a parameter. If interrupts were disabled before
// calling Disable, this will not re-enable interrupts, allowing for nested
// cricital sections.
func Restore(state State) {
	// SREG is at I/O address 0x3f.
	device.AsmFull("out 0x3f, {state}", map[string]interface{}{
		"state": state,
	})
}