simple nanosecond timer using mach_absolute_time

Timer.swift

/*
    var t = Timer()
    
    t.start()
    // do something
    t.stop()

    println("took \(t.seconds)")
*/

import Darwin

struct Timer {
    static var base: UInt64 = 0
    var startTime: UInt64 = 0
    var stopTime: UInt64 = 0

    init() {
        if Timer.base == 0 {
            var info = mach_timebase_info(numer: 0, denom: 0)
            mach_timebase_info(&info)
            Timer.base = UInt64(info.numer / info.denom)
        }
    }

    mutating func start() {
        startTime = mach_absolute_time()
    }

    mutating func stop() {
        stopTime = mach_absolute_time()
    }

    var nanoseconds: UInt64 {
        return stopTime - startTime * Timer.base
    }

    var milliseconds: Double {
        return Double(nanoseconds) / 1_000_000
    }

    var seconds: Double {
        return Double(nanoseconds) / 1_000_000_000
    }
}