# <center> 作業系統工程期末project <br> <font size=5>李奕承 611121212</font></center>
##
我選擇做的是timer(alarm)
先前已經先做了
1.將這學期寫的每個作業組合起來
2.將資料結構課寫的 double_linked_list.a 移植進來
3.實現了顯示所有 task PCB 及系統時間的簡單桌面
(建議老師直接編譯執行，可以看到整個系統的變化)
## PCB結構
```c
typedef struct pcb{
dllNode_t node;
context context;
uint8_t stack[STACK_SIZE];
int ID;
int priority;
int finish;
int waiting;
int error;
reg_t pasue_address;
}pcb_t;
```
當我新增一個 task 時，會 malloc 一個 pcb_t 結構加入 task 清單串列，並設定好必要的值
```c
int task_create(void (*start_routin)(char *param), char *param, uint8_t priority)
{
pcb_t * porcess = (pcb_t *)malloc(sizeof(pcb_t));
if (porcess != NULL) {
porcess->ID = process_ID;
porcess->finish = 0;
porcess->waiting = 0;
porcess->node.next = NULL;
porcess->node.prev = NULL;
porcess->priority = priority;
porcess->pasue_address = (reg_t) start_routin;
porcess->context.sp = (reg_t) &(porcess->stack[STACK_SIZE -1]);
porcess->context.ra = (reg_t) start_routin;
porcess->context.a0 = (reg_t) param;
process_ID++;
DLL_add_tail(&porcess->node, pcb_list);
return 0;
} else {
return -1;
}
}
```
在中斷處理結束前會使用一次 showPCB() 來刷新畫面，畫面中包含
- 畫出一個PCB表格
- 運作中的timer(alarm)
- 系統時間
- 還有使用者輸入過的文字暫存
```c
#include"os.h"
void showPCB()
{
int task_count = DLL_num_nodes(pcb_list);
printf("\033[?25h");
uart_puts("\E[H\E[J");
dllNode_t * target = pcb_list;
printf("\n| task ID ");
while(target->next != NULL)
{
target = DLL_next_node(target);
printf("| %d ", ((pcb_t *)target)->ID);
}
printf("|\n");
printf("------------");
for(int i = 0 ; i < task_count ; i++)
{
printf("---------");
}
printf("\n| priority ");
target = pcb_list;
while(target->next != NULL)
{
target = DLL_next_node(target);
//顯示所有task的優先級
printf("| %d ", ((pcb_t *)target)->priority);
}
printf("|\n");
printf("------------");
for(int i = 0 ; i < task_count ; i++)
{
printf("---------");
}
printf("\n| finish ");
target = pcb_list;
while(target->next != NULL)
{
target = DLL_next_node(target);
if(((pcb_t *)target)->finish == 1)
{
printf("|\033[1;31;1m 1 \033[0;37;1m");
}
else
{
//顯示所有task是否被執行過的狀態
printf("| 0 ");
}
}
printf("|\n");
printf("------------");
for(int i = 0 ; i < task_count ; i++)
{
printf("---------");
}
printf("\n| waiting ");
target = pcb_list;
while(target->next != NULL)
{
target = DLL_next_node(target);
if(((pcb_t *)target)->waiting == 1)
{
printf("|\033[1;31;1m 1 \033[0;37;1m");
}
else
{
//顯示所有task是否被執行過的狀態
printf("| 0 ");
}
}
printf("|\n");
printf("------------");
for(int i = 0 ; i < task_count ; i++)
{
printf("---------");
}
printf("\n| error ");
target = pcb_list;
while(target->next != NULL)
{
target = DLL_next_node(target);
if(((pcb_t *)target)->error == 1)
{
printf("|\033[1;31;1m 1 \033[0;37;1m");
}
else
{
//顯示所有task是否被執行過的狀態
printf("| 0 ");
}
}
printf("|\n\n");
show_alarm();
clock();
printf(":%s", trap_temp);
}
```
畫面長這樣
以下是我為了測試所產生的9個 task ，他們每個會輸出不一樣的圖形。
其中第 3、6、8 task 會在運行時申請一個鬧鐘，並進入等待狀態。
task 2 會故意產生一個異常(上圖可以看到)。
```c
//第1個task
void user_task1(char* santams)
{
printf("Task 1: Running...|%s\n", santams);
uart_puts(" |...\n");
uart_puts(" |...\n");
uart_puts(" |...\n");
asm volatile("wfi");
task_exit();
}
//第2個task
void user_task2(char* santams)
{
printf("Task 2: Running............|.........%s\n", santams);
uart_puts(" ...|\n");
uart_puts(" ...|\n");
uart_puts(" ...|\n");
trap_test();
asm volatile("wfi");
task_exit();
}
//第3個task
void user_task3(char* santams)
{
printf(" Task 3: Running...|%s\n", santams);
uart_puts(" |...\n");
uart_puts(" |...\n");
uart_puts(" |...\n");
create_alarm(20);
task_wait();
asm volatile("wfi");
task_exit();
}
//第4個task
void user_task4(char* santams)
{
printf(" Task 4: Running............|.........%s\n", santams);
uart_puts(" ...|\n");
uart_puts(" ...|\n");
uart_puts(" ...|\n");
asm volatile("wfi");
task_exit();
}
//第5個task
void user_task5(char* santams)
{
printf(" Task 5: Running...|%s\n", santams);
uart_puts(" |...\n");
uart_puts(" |...\n");
uart_puts(" |...\n");
asm volatile("wfi");
task_exit();
}
//第6個task
void user_task6(char* santams)
{
printf(" Task 6: Running............|.........%s\n", santams);
uart_puts(" ...|\n");
uart_puts(" ...|\n");
uart_puts(" ...|\n");
create_alarm(10);
task_wait();
asm volatile("wfi");
task_exit();
}
//第7個task
void user_task7(char* santams)
{
printf(" Task 7: Running...|%s\n", santams);
uart_puts(" |...\n");
uart_puts(" |...\n");
uart_puts(" |...\n");
asm volatile("wfi");
task_exit();
}
//第8個task
void user_task8(char* santams)
{
printf(" Task 8: Running............|.........%s\n", santams);
uart_puts(" ...|\n");
uart_puts(" ...|\n");
uart_puts(" ...|\n");
create_alarm(40);
task_wait();
asm volatile("wfi");
task_exit();
}
//第9個task
void user_task9(char* santams)
{
printf(" Task 9: Running...|%s\n", santams);
uart_puts(" |...\n");
uart_puts(" |...\n");
uart_puts(" |...\n");
asm volatile("wfi");
task_exit();
}
```
## alarm_t 結構
```c
typedef struct alarm{
dllNode_t node;
int tickets;
int ID;
dllNode_t * owner;
}alarm_t;
```
當要產生一個鬧鐘時，會 malloc 一個 alarm_t 結構加入 alarm 清單串列，並設定好必要的值，接著判斷要插在哪個時鐘前面，插入後減掉在這之前所有鬧鐘加總的 tickets，另外我的下一個鬧鐘也要減掉我的 tickets
```c
void create_alarm(int tickets)
{
alarm_t * new = (alarm_t *)malloc(sizeof(alarm_t));
new->node.next = NULL;
new->node.prev = NULL;
new->owner = current_task;
new->tickets = tickets;
new->ID = ((pcb_t *)current_task)->ID;
dllNode_t * temp = alarm_list;
int before = 0;
int after = 0;
while (1)
{
if(temp->next == NULL)
{
DLL_addto_next(&new->node, temp);
new->tickets -= after;
return;
}
else
{
temp = temp->next;
before += after;
after += ((alarm_t *)temp)->tickets;
if(new->tickets < after)
{
DLL_addto_prev(&new->node, temp);
new->tickets -= before;
((alarm_t *)temp)->tickets -= new->tickets;
return;
}
}
}
}
```
每當一個時鐘中斷來時，除了更新系統時間，也會把 alarm 清單串列的第一個鬧鐘減掉 1 ticket ，如果減為0，就把自己從串列中刪除，並把當初申請鬧鐘的 task 喚醒
```c
void alarm_handle()
{
dllNode_t * temp = DLL_next_node(alarm_list);
if(temp != NULL)
{
((alarm_t *)temp)->tickets--;
if(((alarm_t *)temp)->tickets == 0)
{
((pcb_t *)(((alarm_t *)temp)->owner))->waiting = 0;
DLL_delete(temp);
free(temp);
}
}
}
```
alarm_handle() 放在中斷處理程式中 timer_handle()的下面
```c
reg_t trap_handler(reg_t epc, reg_t cause)
{
((pcb_t *)current_task)->pasue_address = epc;
reg_t return_pc = epc;
reg_t cause_code = cause & 0xfff;
if(cause & 0x80000000)
{
switch (cause_code)
{
case 3:
//uart_puts("software interruption!\n");
{
int id = r_mhartid();
*(uint32_t *)CLINT_MSIP(id) = 0;
//((pcb_t *)current_task)->context.ra = return_pc;
showPCB();
//schedule();
current_task = &(manage->node);
return (reg_t)schedule;
}
break;
case 7:
//uart_puts("timer interruption!\n");
timer_handle();
alarm_handle();
break;
case 11:
//uart_puts("external interruption!\n");
external_interrupt_handler();
break;
default:
uart_puts("unknown async exception!\n");
break;
}
}
else
{
printf("Sync exceptions!, code = %d\n", cause_code);
uart_puts("OOPS! What can I do!\n");
uart_puts("next time, this task will start at pc where exeception next \n");
((pcb_t *)current_task)->error = 1;
//return return_pc += 4;
return (reg_t)schedule;
}
showPCB();
return return_pc;
}
```
以下是我的 schedule()
他會掃描整個 task 清單串列，尋找可以執行的task並選出 priority 最大的，然後跳進去執行。如果只剩下 ID 為 0 的task(schedule本身的ID)，代表目前沒有其他事可做，所以會開始回收已經被標註為 finish 或者 error 的 task，將其pcb_t結構從清單中刪除並釋放。
```c
void schedule()
{
int task_count = DLL_num_nodes(pcb_list);
dllNode_t * max = &(manage->node);
dllNode_t * target = pcb_list;
int temp = 0;
while(target->next != NULL)
{
target = DLL_next_node(target);
//找到優先度最高的task，並且必須是沒有被做過的，且沒有在等待中
if(((pcb_t *)target)->priority >= temp && ((pcb_t *)target)->finish != 1 && ((pcb_t *)target)->error == 0 && ((pcb_t *)target)->waiting == 0)
{
//將最優先要做的task編號設給 max 變數
temp = ((pcb_t *)target)->priority;
max = target;
}
}
//如果 ((pcb_t *)max)->priority 為 0 且 ((pcb_t *)max)->finish 也是 0，代表系統目前沒有其他任務要執行
if(((pcb_t *)max)->priority == 0 && ((pcb_t *)max)->finish == 0)
{
current_task = max;
target = pcb_list;
while(target->next != NULL)
{
target = DLL_next_node(target);
if(((pcb_t *)target)->error == 1 || ((pcb_t *)target)->finish == 1)
{
DLL_delete(target);
free(target);
}
}
asm volatile("wfi");
}
//不是的話代表還有task沒做完，於是將下個 task 的 context 指針設為 max 所代表的task 然後switch_to()
else
{
printf("max = task %d\n\n\n", ((pcb_t *)max)->ID);
struct context *next = &(((pcb_t *)max)->context);
current_task = max;
switch_to(next, ((pcb_t *)current_task)->pasue_address);
}
}
```
## 其他
另外，如果程式是正常結束的，finish 就會被標記為 1
```c
void task_exit()
{
((pcb_t *)current_task)->finish = 1;
showPCB();
switch_to( &(manage->context), manage->pasue_address);
}
```
這是我的系統時間
```c
//時間進位的邏輯
void tick()
{
seconds++;
if(seconds == 60)
{
mintues++;
seconds = 0;
if(mintues == 60)
{
hours++;
mintues = 0;
if(hours == 24)
{
hours = 0;
}
}
}
}
```
這是當剩下的3個 task 都在等待鬧鐘喚醒的桌面
所有task都執行完進入閒置狀態的畫面
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