/*
?*??Interrupt?and?PWM?utilities?for?16?bit?Timer1?on?ATmega168/328
?*??Original?code?by?Jesse?Tane?for?http://labs.ideo.com?August?2008
?*??Modified?March?2009?by?Jér?me?Despatis?and?Jesse?Tane?for?ATmega328?support
?*??Modified?June?2009?by?Michael?Polli?and?Jesse?Tane?to?fix?a?bug?in?setPeriod（）?which?caused?the?timer?to?stop
?*??Modified?June?2011?by?Lex?Talionis?to?add?a?function?to?read?the?timer
?*??Modified?Oct?2011?by?Andrew?Richards?to?avoid?certain?problems:
?*??-?Add?（long）?assignments?and?casts?to?TimerOne::read（）?to?ensure?calculations?involving?tmp?ICR1?and?TCNT1?aren‘t?truncated
?*??-?Ensure?16?bit?registers?accesses?are?atomic?-?run?with?interrupts?disabled?when?accessing
?*??-?Remove?global?enable?of?interrupts?（sei（））-?could?be?running?within?an?interrupt?routine）
?*??-?Disable?interrupts?whilst?TCTN1?==?0.??Datasheet?vague?on?this?but?experiment?shows?that?overflow?interrupt?
?*????flag?gets?set?whilst?TCNT1?==?0?resulting?in?a?phantom?interrupt.??Could?just?set?to?1?but?gets?inaccurate
?*????at?very?short?durations
?*??-?startBottom（）?added?to?start?counter?at?0?and?handle?all?interrupt?enabling.
?*??-?start（）?amended?to?enable?interrupts
?*??-?restart（）?amended?to?point?at?startBottom（）
?*?Modiied?7:26?PM?Sunday?October?09?2011?by?Lex?Talionis
?*??-?renamed?start（）?to?resume（）?to?reflect?it‘s?actual?role
?*??-?renamed?startBottom（）?to?start（）.?This?breaks?some?old?code?that?expects?start?to?continue?counting?where?it?left?off
?*
?*??This?program?is?free?software:?you?can?redistribute?it?and/or?modify
?*	it?under?the?terms?of?the?GNU?General?Public?License?as?published?by
?*	the?Free?Software?Foundation?either?version?3?of?the?License?or
?*	（at?your?option）?any?later?version.
?*
?*	This?program?is?distributed?in?the?hope?that?it?will?be?useful
?*	but?WITHOUT?ANY?WARRANTY;?without?even?the?implied?warranty?of
?*	MERCHANTABILITY?or?FITNESS?FOR?A?PARTICULAR?PURPOSE.??See?the
?*	GNU?General?Public?License?for?more?details.
?*
?*	You?should?have?received?a?copy?of?the?GNU?General?Public?License
?*	along?with?this?program.??If?not?see?.
?*
?*??See?Google?Code?project?http://code.google.com/p/arduino-timerone/?for?latest
?*/
#ifndef?TIMERONE_cpp
#define?TIMERONE_cpp

#include?“TimerOne.h“

TimerOne?Timer1;??????????????//?preinstatiate

ISR（TIMER1_OVF_vect）??????????//?interrupt?service?routine?that?wraps?a?user?defined?function?supplied?by?attachInterrupt
{
??Timer1.isrCallback（）;
}


void?TimerOne::initialize（long?microseconds）
{
??TCCR1A?=?0;?????????????????//?clear?control?register?A?
??TCCR1B?=?_BV（WGM13）;????????//?set?mode?8:?phase?and?frequency?correct?pwm?stop?the?timer
??setPeriod（microseconds）;
}


void?TimerOne::setPeriod（long?microseconds）		//?AR?modified?for?atomic?access
{
??
??long?cycles?=?（F_CPU?/?2000000）?*?microseconds;????????????????????????????????//?the?counter?runs?backwards?after?TOP?interrupt?is?at?BOTTOM?so?divide?microseconds?by?2
??if（cycles?