[refactor] 整理注释

kernel/scheduler/scheduler.cpp

@@ -6,15 +6,15 @@
 #include <common.h>
 #include <serial.h>
 
-// Assembly: context_switch(UINT64* old_rsp, UINT64 new_rsp)
+// 汇编函数：context_switch(UINT64* old_rsp, UINT64 new_rsp)
 extern "C" void context_switch(UINT64* old_rsp, UINT64 new_rsp);
 
 static task_t  g_tasks[TASK_MAX];
 static UINT32  g_task_count = 0;
 static task_t* g_current = NULL;
-static task_t* g_task_list = NULL;  // circular linked list head
+static task_t* g_task_list = NULL;  // 循环链表头
 
-// Trampoline: first thing a new task runs after context_switch.
+// 跳板函数：新任务在 context_switch 后首先执行的函数
 static void (*g_task_entries[TASK_MAX])(void);
 
 extern "C" void task_entry_trampoline() {
@@ -37,7 +37,7 @@ task_t* task_create(const char* name, void (*entry)(void)) {
 
     g_task_entries[id] = entry;
 
-    // Allocate kernel stack
+    // 分配内核栈
     UINTN stack_pages = TASK_STACK_SIZE / PAGE_SIZE;
     void* stack = pmm_alloc_pages(stack_pages);
     if (!stack) {
@@ -52,24 +52,21 @@ task_t* task_create(const char* name, void (*entry)(void)) {
     task->stack_base = stack;
     task->time_slice = TIME_SLICE_DEFAULT;
 
-    // Copy name
+    // 复制任务名称
     str_copy(task->name, name, TASK_NAME_LEN);
 
-    // Set up initial stack for first context_switch into this task.
-    // Stack grows downward. context_switch will pop 6 regs then ret.
+    // 设置首次 context_switch 时的初始栈
+    // 栈向下增长。context_switch 会弹出 6 个寄存器然后 ret。
     //
-    // Layout (high addr -> low addr):
-    //   [stack + TASK_STACK_SIZE]     <- top
-    //   return addr = task_entry_trampoline  (ret goes here)
+    // 布局（高地址 → 低地址）：
+    //   [stack + TASK_STACK_SIZE]     <- 栈顶
+    //   返回地址 = task_entry_trampoline（ret 跳转到这里）
     //   rbx = 0
     //   rbp = 0
     //   r12 = 0
     //   r13 = 0
     //   r14 = 0
-    //   r15 = 0                       <- RSP points here initially
-    //
-    // When preempted by timer IRQ, the ISR stub saves a full trap_frame
-    // on the task's stack — that layout is only created by hardware+ISR.
+    //   r15 = 0                       <- RSP 初始指向这里
     //
     UINT64* sp = (UINT64*)((UINT8*)stack + TASK_STACK_SIZE);
 
@@ -84,7 +81,7 @@ task_t* task_create(const char* name, void (*entry)(void)) {
 
     task->rsp = (UINT64)sp;
 
-    // Insert into circular linked list
+    // 插入循环链表
     if (g_task_list == NULL) {
         task->next = task;
         g_task_list = task;
@@ -103,7 +100,7 @@ task_t* task_create(const char* name, void (*entry)(void)) {
     return task;
 }
 
-// Find next READY task in the circular list, starting from g_current->next
+// 在循环链表中查找下一个就绪任务
 static task_t* find_next_ready(void) {
     if (g_current == NULL || g_task_list == NULL) return NULL;
 
@@ -117,7 +114,7 @@ static task_t* find_next_ready(void) {
         next = next->next;
     } while (next != start);
 
-    return NULL;  // no READY tasks
+    return NULL;  // 没有就绪任务
 }
 
 void yield(void) {
@@ -137,27 +134,27 @@ void yield(void) {
     context_switch(&cur->rsp, next->rsp);
 }
 
-// Timer tick handler — called from PIT IRQ 0
+// 定时器 tick 处理 — 由 PIT IRQ 0 调用
 void scheduler_tick(void) {
     if (g_current == NULL) return;
 
-    // Decrement time slice
+    // 递减时间片
     if (g_current->time_slice > 0) {
         g_current->time_slice--;
     }
 
-    // If time slice expired, preempt
+    // 时间片用完则抢占
     if (g_current->time_slice == 0) {
         task_t* cur = g_current;
         task_t* next = find_next_ready();
 
         if (next == NULL || next == cur) {
-            // No other task ready, or only this task — reload time slice
+            // 没有其他就绪任务，或仅此一个 — 重置时间片
             cur->time_slice = TIME_SLICE_DEFAULT;
             return;
         }
 
-        // Preempt
+        // 抢占
         cur->state = TASK_STATE_READY;
         cur->time_slice = TIME_SLICE_DEFAULT;
         next->state = TASK_STATE_RUNNING;
@@ -174,7 +171,7 @@ void scheduler_run(void) {
         return;
     }
 
-    // Find first READY task
+    // 查找第一个就绪任务
     task_t* start = g_task_list->next;
     task_t* t = start;
     do {
@@ -197,12 +194,12 @@ void scheduler_run(void) {
     serial_write(t->name);
     serial_write("'\n");
 
-    // First context switch — switch to the task's stack
-    // This will never return (until all tasks terminate)
+    // 首次上下文切换 — 切换到任务栈
+    // 此后不会返回（直到所有任务终止）
     UINT64 dummy_rsp;
     context_switch(&dummy_rsp, t->rsp);
 
-    // We only return here when ALL tasks are terminated
+    // 只有所有任务终止后才会返回到这里
     serial_write("SCHED: all tasks finished\n");
     while (1) ASM ("hlt");
 }
@@ -216,10 +213,10 @@ void task_exit(void) {
 
     g_current->state = TASK_STATE_TERMINATED;
 
-    // Yield to next task — we won't come back
+    // 让出 CPU 给下一个任务 — 不会回来
     yield();
 
-    // Should never reach here
+    // 不应到达此处
     while (1) ASM ("hlt");
 }