#include?“devices/timer.h“
#include?
#include?
#include?
#include?
#include?“threads/interrupt.h“
#include?“threads/io.h“
#include?“threads/synch.h“
#include?“threads/thread.h“
/*?My?Implementation?*/
#include?“threads/alarm.h“
#include?“threads/fixed-point.h“
/*?==?My?Implementation?*/
??
/*?See?[8254]?for?hardware?details?of?the?8254?timer?chip.?*/

#if?TIMER_FREQ?#error?8254?timer?requires?TIMER_FREQ?>=?19
#endif
#if?TIMER_FREQ?>?1000
#error?TIMER_FREQ?<=?1000?recommended
#endif

/*?Number?of?timer?ticks?since?OS?booted.?*/
static?int64_t?ticks;

/*?Number?of?loops?per?timer?tick.
???Initialized?by?timer_calibrate（）.?*/
static?unsigned?loops_per_tick;

static?intr_handler_func?timer_interrupt;
static?bool?too_many_loops?（unsigned?loops）;
static?void?busy_wait?（int64_t?loops）;
static?void?real_time_sleep?（int64_t?num?int32_t?denom）;
static?void?real_time_delay?（int64_t?num?int32_t?denom）;

/*?Sets?up?the?8254?Programmable?Interval?Timer?（PIT）?to
???interrupt?PIT_FREQ?times?per?second?and?registers?the
???corresponding?interrupt.?*/
void
timer_init?（void）?
{
??/*?8254?input?frequency?divided?by?TIMER_FREQ?rounded?to
?????nearest.?*/
??uint16_t?count?=?（1193180?+?TIMER_FREQ?/?2）?/?TIMER_FREQ;

??outb?（0x43?0x34）;????/*?CW:?counter?0?LSB?then?MSB?mode?2?binary.?*/
??outb?（0x40?count?&?0xff）;
??outb?（0x40?count?>>?8）;

??intr_register_ext?（0x20?timer_interrupt?“8254?Timer“）;
}

/*?Calibrates?loops_per_tick?used?to?implement?brief?delays.?*/
void
timer_calibrate?（void）?
{
??unsigned?high_bit?test_bit;

??ASSERT?（intr_get_level?（）?==?INTR_ON）;
??printf?（“Calibrating?timer...??“）;

??/*?Approximate?loops_per_tick?as?the?largest?power-of-two
?????still?less?than?one?timer?tick.?*/
??loops_per_tick?=?1u?<??while?（!too_many_loops?（loops_per_tick?<????{
??????loops_per_tick?<<=?1;
??????ASSERT?（loops_per_tick?!=?0）;
????}

??/*?Refine?the?next?8?bits?of?loops_per_tick.?*/
??high_bit?=?loops_per_tick;
??for?（test_bit?=?high_bit?>>?1;?test_bit?!=?high_bit?>>?10;?test_bit?>>=?1）
????if?（!too_many_loops?（high_bit?|?test_bit））
??????loops_per_tick?|=?test_bit;

??printf?（“%‘“PRIu64“?loops/s.\n“?（uint64_t）?loops_per_tick?*?TIMER_FREQ）;
}

/*?Returns?the?number?of?timer?ticks?since?the?OS?booted.?*/
int64_t
timer_ticks?（void）?
{
??enum?intr_level?old_level?=?intr_disable?（）;
??int64_t?t?=?ticks;
??intr_set_level?（old_level）;
??barrier?（）;
??return?t;
}

/*?Returns?the?number?of?timer?ticks?elapsed?since?THEN?which
???should?be?a?value?once?returned?by?timer_ticks（）.?*/
int64_t
timer_elapsed?（int64_t?then）?
{
??return?timer_ticks?（）?-?then;
}

/*?Sleeps?for?approximately?TICKS?timer?ticks.??Interrupts?must
???be?turned?on.?*/
void
timer_sleep?（int64_t?ticks）?
{
??/*?Old?Implementation
??int64_t?start?=?timer_ticks?（）;?*/

??ASSERT?（intr_get_level?（）?==?INTR_ON）;
??/*?Old?Implementation
??while?（timer_elapsed?（start）?????thread_yield?（）;?*/
????
??/*?My?Implementation?*/
??set_alarm

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----

?????文件???????7245??2013-06-19?00:27??10112510138?高皆慶\devices\timer.c

?????文件???????3684??2013-05-28?21:58??10112510138?高皆慶\Makefile.build

?????文件?????927973??2013-06-19?20:12??10112510138?高皆慶\README.pdf

?????文件??????23157??2013-06-19?00:27??10112510138?高皆慶\threads\thread.c

?????文件???????6878??2013-06-19?00:27??10112510138?高皆慶\threads\thread.h

?????文件???????6967??2013-06-19?13:44??10112510138?高皆慶\userprog\exception.c

?????文件????????408??2013-06-19?00:27??10112510138?高皆慶\userprog\exception.h

?????文件??????18856??2013-06-19?13:39??10112510138?高皆慶\userprog\process.c

?????文件????????246??2013-06-19?00:27??10112510138?高皆慶\userprog\process.h

?????文件??????10625??2013-06-19?13:39??10112510138?高皆慶\userprog\syscall.c

?????文件????????143??2013-06-19?00:27??10112510138?高皆慶\userprog\syscall.h

?????目錄??????????0??2013-06-19?02:56??10112510138?高皆慶\devices

?????目錄??????????0??2013-06-19?13:47??10112510138?高皆慶\threads

?????目錄??????????0??2013-06-19?13:45??10112510138?高皆慶\userprog

?????目錄??????????0??2013-06-19?20:12??10112510138?高皆慶

-----------?---------??----------?-----??----

??????????????1006182????????????????????15