package cpu

// CPU represents the processor.
type CPU struct {
	General []Register
	Syscall []Register
	Input   []Register
	Output  []Register
	usage   uint64
}

func (c *CPU) Use(reg Register) {
	c.usage |= (1 << reg)
}

func (c *CPU) Free(reg Register) {
	c.usage &= ^(1 << reg)
}

func (c *CPU) IsFree(reg Register) bool {
	return c.usage&(1<<reg) == 0
}

func (c *CPU) FindFree(registers []Register) (Register, bool) {
	for _, reg := range registers {
		if c.IsFree(reg) {
			return reg, true
		}
	}

	return 0, false
}

func (c *CPU) MustFindFree(registers []Register) Register {
	register, exists := c.FindFree(registers)

	if !exists {
		panic("no free registers")
	}

	return register
}