真沒想到還可以這樣寫狀態(tài)機(jī)！QP嵌入式實(shí)時(shí)框架
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好萊塢原則：和傳統(tǒng)的順序式編程方法例如“超級循環(huán)”，或傳統(tǒng)的RTOS 的任務(wù)不同。絕大多數(shù)的現(xiàn)代事件驅(qū)動(dòng)型系統(tǒng)根據(jù)好萊塢原則被構(gòu)造（Don’t call me; I’ll call you.）
QP官網(wǎng)：http://www.state-machine.com/
面向?qū)ο?/span>類和單一繼承：
QM ：一個(gè)通過UML類圖來描述狀態(tài)機(jī)的軟件，并且可以自動(dòng)生成C代碼
QS軟件追蹤工具：
/* qevent.h ----------------------------------------------------------------*/
typedef struct QEventTag
{
QSignal sig;
uint8_t dynamic_;
} QEvent;
/* qep.h -------------------------------------------------------------------*/
typedef uint8_t QState; /* status returned from a state-handler function */
typedef QState (*QStateHandler) (void *me, QEvent const *e); /* argument list */
typedef struct QFsmTag /* Finite State Machine */
{
QStateHandler state; /* current active state */
}QFsm;
#define QFsm_ctor(me_, initial_) ((me_)->state = (initial_))
void QFsm_init (QFsm *me, QEvent const *e);
void QFsm_dispatch(QFsm *me, QEvent const *e);
#define Q_RET_HANDLED ((QState)0)
#define Q_RET_IGNORED ((QState)1)
#define Q_RET_TRAN ((QState)2)
#define Q_HANDLED() (Q_RET_HANDLED)
#define Q_IGNORED() (Q_RET_IGNORED)
#define Q_TRAN(target_) (((QFsm *)me)->state = (QStateHandler) (target_),Q_RET_TRAN)
enum QReservedSignals
{
Q_ENTRY_SIG = 1,
Q_EXIT_SIG,
Q_INIT_SIG,
Q_USER_SIG
};
/* file qfsm_ini.c ---------------------------------------------------------*/
#include "qep_port.h" /* the port of the QEP event processor */
#include "qassert.h" /* embedded systems-friendly assertions */
void QFsm_init(QFsm *me, QEvent const *e)
{
(*me->state)(me, e); /* execute the top-most initial transition */
/* enter the target */
(void)(*me->state)(me , &QEP_reservedEvt_[Q_ENTRY_SIG]);
}
/* file qfsm_dis.c ---------------------------------------------------------*/
void QFsm_dispatch(QFsm *me, QEvent const *e)
{
QStateHandler s = me->state; /* save the current state */
QState r = (*s)(me, e); /* call the event handler */
if (r == Q_RET_TRAN) /* transition taken? */
{
(void)(*s)(me, &QEP_reservedEvt_[Q_EXIT_SIG]); /* exit the source */
(void)(*me->state)(me, &QEP_reservedEvt_[Q_ENTRY_SIG]);/*enter target*/
}
}
實(shí)現(xiàn)上面定時(shí)器例子
#include "qep_port.h" /* the port of the QEP event processor */
#include "bsp.h" /* board support package */
enum BombSignals /* all signals for the Bomb FSM */
{
UP_SIG = Q_USER_SIG,
DOWN_SIG,
ARM_SIG,
TICK_SIG
};
typedef struct TickEvtTag
{
QEvent super; /* derive from the QEvent structure */
uint8_t fine_time; /* the fine 1/10 s counter */
}TickEvt;
typedef struct Bomb4Tag
{
QFsm super; /* derive from QFsm */
uint8_t timeout; /* number of seconds till explosion */
uint8_t code; /* currently entered code to disarm the bomb */
uint8_t defuse; /* secret defuse code to disarm the bomb */
} Bomb4;
void Bomb4_ctor (Bomb4 *me, uint8_t defuse);
QState Bomb4_initial(Bomb4 *me, QEvent const *e);
QState Bomb4_setting(Bomb4 *me, QEvent const *e);
QState Bomb4_timing (Bomb4 *me, QEvent const *e);
/*--------------------------------------------------------------------------*/
/* the initial value of the timeout */
#define INIT_TIMEOUT 10
/*..........................................................................*/
void Bomb4_ctor(Bomb4 *me, uint8_t defuse) {
QFsm_ctor_(&me->super, (QStateHandler)&Bomb4_initial);
me->defuse = defuse; /* the defuse code is assigned at instantiation */
}
/*..........................................................................*/
QState Bomb4_initial(Bomb4 *me, QEvent const *e) {
(void)e;
me->timeout = INIT_TIMEOUT;
return Q_TRAN(&Bomb4_setting);
}
/*..........................................................................*/
QState Bomb4_setting(Bomb4 *me, QEvent const *e) {
switch (e->sig){
case UP_SIG:{
if (me->timeout < 60) {
++me->timeout;
BSP_display(me->timeout);
}
return Q_HANDLED();
}
case DOWN_SIG: {
if (me->timeout > 1) {
--me->timeout;
BSP_display(me->timeout);
}
return Q_HANDLED();
}
case ARM_SIG: {
return Q_TRAN(&Bomb4_timing); /* transition to "timing" */
}
}
return Q_IGNORED();
}
/*..........................................................................*/
void Bomb4_timing(Bomb4 *me, QEvent const *e) {
switch (e->sig) {
case Q_ENTRY_SIG: {
me->code = 0; /* clear the defuse code */
return Q_HANDLED();
}
case UP_SIG: {
me->code <<= 1;
me->code |= 1;
return Q_HANDLED();
}
case DOWN_SIG: {
me->code <<= 1;
return Q_HANDLED();
}
case ARM_SIG: {
if (me->code == me->defuse) {
return Q_TRAN(&Bomb4_setting);
}
return Q_HANDLED();
}
case TICK_SIG: {
if (((TickEvt const *)e)->fine_time == 0) {
--me->timeout;
BSP_display(me->timeout);
if (me->timeout == 0) {
BSP_boom(); /* destroy the bomb */
}
}
return Q_HANDLED();
}
}
return Q_IGNORED();
}
優(yōu)點(diǎn)：
- 采用面向?qū)ο蟮脑O(shè)計(jì)方法，很好的移植性
- 實(shí)現(xiàn)了進(jìn)入退出動(dòng)作
- 合適的粒度，且事件的粒度可控
- 狀態(tài)切換時(shí)通過改變指針，效率高
- 可擴(kuò)展成為層次狀態(tài)機(jī)
缺點(diǎn)：
- 對事件的定義以及事件粒度的控制是設(shè)計(jì)的最大難點(diǎn)，如串口接收到一幀數(shù)據(jù)，這些變量的更新單獨(dú)作為某個(gè)事件，還是串口收到數(shù)據(jù)作為一個(gè)事件。再或者顯示屏，如果使用此種編程方式，如何設(shè)計(jì)事件。
初始化層次狀態(tài)機(jī)的實(shí)現(xiàn)：在初始化時(shí)，用戶所選取的狀態(tài)永遠(yuǎn)是最底層的狀態(tài)，如上圖，我們在計(jì)算器開機(jī)后，應(yīng)該進(jìn)入的是開始狀態(tài)，這就涉及到一個(gè)問題，由最初top（頂狀態(tài)）到begin 是有一條狀態(tài)切換路徑的，當(dāng)我們設(shè)置狀態(tài)為begin如何搜索這條路徑成為關(guān)鍵（知道了路徑才能正確的進(jìn)入begin,要執(zhí)行路徑中過渡狀態(tài)的進(jìn)入和退出事件）。
void QHsm_init(QHsm *me, QEvent const *e)
{
Q_ALLEGE((*me->state)(me, e) == Q_RET_TRAN);
t = (QStateHandler)&QHsm_top; /* HSM starts in the top state */
do { /* drill into the target... */
QStateHandler path[QEP_MAX_NEST_DEPTH_];
int8_t ip = (int8_t)0; /* transition entry path index */
path[0] = me->state; /* 這里的狀態(tài)為begin */
/*通過執(zhí)行空信號，從底層狀態(tài)找到頂狀態(tài)的路徑*/
(void)QEP_TRIG_(me->state, QEP_EMPTY_SIG_);
while (me->state != t) {
path[++ip] = me->state;
(void)QEP_TRIG_(me->state, QEP_EMPTY_SIG_);
}
/*切換為begin*/
me->state = path[0]; /* restore the target of the initial tran. */
/* 鉆到最底層的狀態(tài)，執(zhí)行路徑中的所有進(jìn)入事件 */
Q_ASSERT(ip < (int8_t)QEP_MAX_NEST_DEPTH_);
do { /* retrace the entry path in reverse (desired) order... */
QEP_ENTER_(path[ip]); /* enter path[ip] */
} while ((--ip) >= (int8_t)0);
t = path[0]; /* current state becomes the new source */
} while (QEP_TRIG_(t, Q_INIT_SIG) == Q_RET_TRAN);
me->state = t;
}
狀態(tài)切換：
/*.................................................................*/
QState result(Calc *me, QEvent const *e)
{
switch (e->sig)
{you
case ENTER_SIG:{
break;
}
case EXIT_SIG:{
break;
}
case C_SIG:
{
printf("clear");
return Q_HANDLED();
}
case B_SIG:
{
return Q_TRAN(&begin);
}
}
return Q_SUPER(&reday);
}
/*.ready為result和begin的超狀態(tài)................................................*/
QState ready(Calc *me, QEvent const *e)
{
switch (e->sig)
{
case ENTER_SIG:{
break;
}
case EXIT_SIG:{
break;
}
case OPER_SIG:
{
return Q_TRAN(&opEntered);
}
}
return Q_SUPER(&on);
}
void QHsm_dispatch(QHsm *me, QEvent const *e)
{
QStateHandler path[QEP_MAX_NEST_DEPTH_];
QStateHandler s;
QStateHandler t;
QState r;
t = me->state; /* save the current state */
do { /* process the event hierarchically... */
s = me->state;
r = (*s)(me, e); /* invoke state handler s */
} while (r == Q_RET_SUPER); //當(dāng)前狀態(tài)不能處理事件 ，直到找到能處理事件的狀態(tài)
if (r == Q_RET_TRAN) { /* transition taken? */
int8_t ip = (int8_t)(-1); /* transition entry path index */
int8_t iq; /* helper transition entry path index */
path[0] = me->state; /* save the target of the transition */
path[1] = t;
while (t != s) { /* exit current state to transition source s... */
if (QEP_TRIG_(t, Q_EXIT_SIG) == Q_RET_HANDLED) {/*exit handled? */
(void)QEP_TRIG_(t, QEP_EMPTY_SIG_); /* find superstate of t */
}
t = me->state; /* me->state holds the superstate */
}
. . .
}
me->state = t; /* set new state or restore the current state */
}
t = path[0]; /* target of the transition */4 QP實(shí)時(shí)框架的組成
if (s == t) { /* (a) check source==target (transition to self) */
QEP_EXIT_(s) /* exit the source */
ip = (int8_t)0; /* enter the target */
}
else {
(void)QEP_TRIG_(t, QEP_EMPTY_SIG_); /* superstate of target */
t = me->state;
if (s == t) { /* (b) check source==target->super */
ip = (int8_t)0; /* enter the target */
}
else {
(void)QEP_TRIG_(s, QEP_EMPTY_SIG_); /* superstate of src */
/* (c) check source->super==target->super */
if(me->state == t) {
QEP_EXIT_(s) /* exit the source */
ip = (int8_t)0; /* enter the target */
}
else {
/* (d) check source->super==target */
if (me->state == path[0]) {
QEP_EXIT_(s) /* exit the source */
}
else { /* (e) check rest of source==target->super->super..
* and store the entry path along the way */
....
使用內(nèi)存池，對于低性能mcu，內(nèi)存極為有限，引入內(nèi)存管理主要是整個(gè)架構(gòu)中，是以事件作為主要的任務(wù)通信手段，且事件是帶參數(shù)的，可能相同類型的事件會(huì)多次觸發(fā)，而事件處理完成后，需要清除事件，無法使用靜態(tài)的事件，因此是有必要為不同事件創(chuàng)建內(nèi)存池的。對于不同塊大小的內(nèi)存池，需要考慮的是每個(gè)塊的起始地址對齊問題。在進(jìn)行內(nèi)存池初始化時(shí)，我們是根據(jù)blocksize+header大小來進(jìn)行劃分內(nèi)存池的。假設(shè)一個(gè)2字節(jié)的結(jié)構(gòu)，如果以2來進(jìn)行劃分，假設(shè)mcu 4字節(jié)對齊，那么將有一半的結(jié)構(gòu)起始地址無法對齊，這時(shí)需要為每個(gè)塊預(yù)留空間，保證每個(gè)塊的對齊。
每一個(gè)活動(dòng)對象維護(hù)一個(gè)事件隊(duì)列，事件都是由基礎(chǔ)事件派生的，不同類型的事件只需要將其基礎(chǔ)事件成員添加到活動(dòng)對象的隊(duì)列中即可，最終在取出的時(shí)候通過一個(gè)強(qiáng)制轉(zhuǎn)換便能獲得附加的參數(shù)。
- 直接事件發(fā)送 QActive_postLIFO()
- 發(fā)行訂閱事件發(fā)送 豎軸表示信號（為事件的基類） 活動(dòng)對象支持64個(gè)優(yōu)先級，每一個(gè)活動(dòng)對象要求擁有唯一優(yōu)先級 通過優(yōu)先級的bit位來表示某個(gè)事件被哪些活動(dòng)對象訂閱，并在事件觸發(fā)后根據(jù)優(yōu)先級為活動(dòng)對象派發(fā)事件。
一鍵三連，公眾號后臺回復(fù)【QP】可以獲取資料
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