diff --git a/datastruct/list.c b/datastruct/list.c
index 28c5332..001f8ed 100644
--- a/datastruct/list.c
+++ b/datastruct/list.c
@@ -1,365 +1,6 @@
 
 #include "list.h"
 
-
-#ifdef LINK_LIST
-bool list_init(plist_t *list)
-{
-	*list = (plist_t)malloc(sizeof(list_t));
-	if(*list == NULL)
-	{
-		return false;
-	}
-	(*list)->data = (list_data_t)0;
-	(*list)->prev = *list;
-	(*list)->next = *list;
-	return true;
-}
-
-void list_destroy(plist_t *list)
-{
-	if (*list != NULL)
-	{
-		list_clear(*list);
-		free(*list);
-		(*list)->prev = NULL;
-		(*list)->next = NULL;
-		*list = NULL;
-	}
-}
-
-bool list_empty(plist_t list)
-{
-	return (list == NULL || (list->prev == list && list->next == list)) ? true : false;
-}
-
-void list_clear(plist_t list)
-{
-	if(!list_empty(list))
-	{
-		plist_t p = list->next;
-		plist_t ptmp = p;
-		while(p != list)
-		{
-			ptmp = p;
-			p->prev->next = p->next;
-			p->next->prev = p->prev;
-			p = p->next;
-
-			// finally free memory
-			free(ptmp);
-			ptmp->prev = NULL;
-			ptmp->next = NULL;
-		}
-	}
-}
-
-bool list_insert_head(plist_t list, list_data_t data)
-{
-	plist_t new_item;
-	if(list == NULL)
-	{
-		return false;
-	}
-
-	new_item = (plist_t)malloc(sizeof(list_t));
-	if(new_item == NULL)
-	{
-		return false;
-	}
-	new_item->data = data;
-
-	// insert from head
-	new_item->next = list->next;
-	new_item->prev = list->next->prev;
-	list->next->prev = new_item;
-	list->next = new_item;
-
-	return true;
-}
-
-bool list_insert_tail(plist_t list, list_data_t data)
-{
-	plist_t new_item;
-	if(list == NULL)
-	{
-		return false;
-	}
-
-	new_item = (plist_t)malloc(sizeof(list_t));
-	if(new_item == NULL)
-	{
-		return false;
-	}
-	new_item->data = data;
-
-	// insert from tail
-	new_item->prev = list->prev;
-	new_item->next = list->prev->next;
-	list->prev->next = new_item;
-	list->prev = new_item;
-
-	return true;
-}
-
-bool list_delete(plist_t list, list_data_t data)
-{
-	if(!list_empty(list))
-	{
-		plist_t p = list;
-		while(p->next != list)
-		{
-			p = p->next;
-			if(p->data == data)
-			{
-				// delete the item
-				p->prev->next = p->next;
-				p->next->prev = p->prev;
-				free(p);
-				p->prev = NULL;
-				p->next = NULL;
-				return true;
-			}
-		}
-	}
-	return false;
-}
-
-uint32_t list_count(plist_t list)
-{
-	uint32_t count = 0;
-	if(!list_empty(list))
-	{
-		plist_t p = list;
-		while(p->next != list)
-		{
-			p = p->next;
-			count++;
-		}
-	}
-	return count;
-}
-
-void list_traversal_sequence(plist_t list, list_data_disp_t disp)
-{
-	if(!list_empty(list))
-	{
-		plist_t p = list->next;
-		while(p != list)
-		{
-			disp(p->data);
-			p = p->next;
-		}
-	}
-}
-
-void list_traversal_reversed(plist_t list, list_data_disp_t disp)
-{
-	if(!list_empty(list))
-	{
-		plist_t p = list->prev;
-		while(p != list)
-		{
-			disp(p->data);
-			p = p->prev;
-		}
-	}
-}
-#endif
-
-#if 0
-bool list_init(list_t list)
-{
-	// list->capacity = 64;
-	list->capacity = 8;
-
-	list->size = 0;
-	list->extend_ratio = 2;
-	list->array = (list_data_t *)malloc(list->capacity * sizeof(list_data_t));
-	if (list->array == NULL)
-	{
-		return false;
-	}
-	return true;
-}
-
-void list_destory(list_t list)
-{
-	if (list->array != NULL)
-	{
-		free(list->array);
-	}
-}
-
-int list_capacity(list_t list)
-{
-	return list->capacity;
-}
-
-int list_size(list_t list)
-{
-	return list->size;
-}
-
-bool list_empty(list_t list)
-{
-	return list_size(list) == 0 ? true : false;
-}
-
-bool list_insert(list_t list, int index, list_data_t data)
-{
-	assert(index >= 0 && index <= list_size(list));
-	if (list_size(list) == list_capacity(list))
-	{
-		int capacity = list->capacity * list->extend_ratio;
-		list_data_t * array = (list_data_t*)realloc(list->array, capacity * sizeof(list_data_t));
-		if (array == NULL)
-		{
-			return false;
-		}
-		list->array = array;
-		list->capacity = capacity;
-	}
-	memmove(&list->array[index + 1], &list->array[index], list_size(list) * sizeof(list_data_t));
-	list->array[index] = data;
-	list->size += 1;
-	return true;
-}
-
-bool list_append(list_t list, list_data_t data)
-{
-	if (list_size(list) == list_capacity(list))
-	{
-		int capacity = list->capacity * list->extend_ratio;
-		list_data_t * array = (list_data_t*)realloc(list->array, capacity * sizeof(list_data_t));
-		if (array == NULL)
-		{
-			return false;
-		}
-		list->array = array;
-		list->capacity = capacity;
-	}
-	list->array[list->size] = data;
-	list->size += 1;
-	return true;
-}
-
-int list_delete(list_t list, int index)
-{
-	assert(index >= 0 && index < list_size(list));
-	int temp = 0;
-	temp = list->array[index];
-	if (index != list_size(list))
-	{
-		memmove(&list->array[index], &list->array[index + 1], (list_size(list) - 1 - index) * sizeof(list_data_t));
-		//for (int i = index; i < list_size(list) - 1; i++)
-		//{
-		//	list->array[i] = list->array[i + 1];
-		//}
-	}
-	list->size -= 1;
-	return temp;
-}
-
-bool list_clear(list_t list)
-{
-	memset(list->array, 0, list->size);
-	list->size = 0;
-	return true;
-}
-
-list_data_t list_get(list_t list, int index)
-{
-	assert(index >= -list_size(list) && index < list_size(list));
-	return index >= 0 ? list->array[index] : list->array[list_size(list) + index];
-}
-
-bool list_set(list_t list, int index, list_data_t data)
-{
-	assert(index >= 0 && index < list_size(list));
-	list->array[index] = data;
-	return true;
-}
-
-void list_print(list_t list)
-{
-	if (!list_empty(list))
-	{
-		for (int i = 0; i < list_size(list); i++)
-		{
-			printf("%2d ", list->array[i]);
-		}
-		printf("\n");
-	}
-}
-
-void list_test(void)
-{
-	int i = 0;
-	
-	list_data_t data = 0;
-	struct _list list;
-	list_init(&list);
-
-	printf("----- append -----\n");
-	for (i = 0; i < 18; i++)
-	{
-		list_append(&list, i);
-		list_print(&list);
-	}
-
-	printf("----- delete -----\n");
-	list_delete(&list, 17);
-	list_print(&list);
-
-	list_delete(&list, 0);
-	list_print(&list);
-
-	list_delete(&list, 9);
-	list_print(&list);
-
-	printf("----- clear -----\n");
-	list_clear(&list);
-	printf("----- insert -----\n");
-	for (i = 0; i < 18; i++)
-	{
-		list_insert(&list, 0, i);
-		list_print(&list);
-	}
-
-	printf("----- get -----\n");
-	data = list_get(&list, 0);
-	printf("list[0] = %2d\n", data);
-
-	data = list_get(&list, 17);
-	printf("list[17] = %2d\n", data);
-
-	data = list_get(&list, 5);
-	printf("list[5] = %2d\n", data);
-
-	printf("----- like python -----\n");
-	data = list_get(&list, -1);
-	printf("list[-1] = %2d\n", data);
-
-	data = list_get(&list, -5);
-	printf("list[-5] = %2d\n", data);
-
-	data = list_get(&list, -18);
-	printf("list[-18] = %2d\n", data);
-
-	printf("----- set -----\n");
-	for (i = 0; i < 18; i++)
-	{
-		list_set(&list, i, i);
-		list_print(&list);
-	}
-
-	list_print(&list);
-	list_destory(&list);
-}
-
-#endif
-
 bool list_append(struct _list* self, void* obj)
 {
 	assert(self != NULL);
@@ -385,27 +26,9 @@ bool list_append(struct _list* self, void* obj)
 	return true;
 }
 
-bool list_clear(struct _list* self)
+bool list_insert(struct _list* self, int index, void* obj)
 {
-	assert(self != NULL);
-	self->_size = 0;
-	return true;
-}
-
-bool list_empty(struct _list* self)
-{
-	assert(self != NULL);
-	return !self->size(self);
-}
-
-uint32_t list_index(struct _list* self, void* obj)
-{
-	return 0;
-}
-
-bool list_insert(struct _list* self, uint32_t index, void* obj)
-{
-	assert(index >= 0 && index < self->size(self));
+	assert(index >= 0 && index < (int)self->size(self));
 
 	if (self->size(self) == self->_capacity)
 	{
@@ -421,7 +44,7 @@ bool list_insert(struct _list* self, uint32_t index, void* obj)
 	uint32_t offset = index * self->_obj_size;
 	uint32_t offset1 = (index + 1) * self->_obj_size;
 
-	memmove((char*)self->obj + offset, (char *)self->obj + offset, self->size(self) * self->_obj_size);
+	memmove((char*)self->obj + offset, (char*)self->obj + offset, self->size(self) * self->_obj_size);
 	self->_size += 1;
 	return true;
 }
@@ -453,7 +76,25 @@ bool list_pop(struct _list* self, int index, void* obj)
 	return true;
 }
 
-bool list_at(struct _list* self, int index, void *obj)
+uint32_t list_index(struct _list* self, void* obj)
+{
+	return 0;
+}
+
+bool list_remove(struct _list* self, void* obj)
+{
+	assert(self != NULL);
+	return true;
+}
+
+bool list_clear(struct _list* self)
+{
+	assert(self != NULL);
+	self->_size = 0;
+	return true;
+}
+
+bool list_get(struct _list* self, int index, void* obj)
 {
 	assert(self != NULL);
 	assert(obj != NULL);
@@ -486,27 +127,10 @@ uint32_t list_size(struct _list* self)
 	return self->_size;
 }
 
-bool list_remove(struct _list* self, int index)
+bool list_empty(struct _list* self)
 {
 	assert(self != NULL);
-	assert(index >= (int)(0 - self->size(self)) && index < (int)self->size(self));
-
-	if (self->empty(self))
-	{
-		return false;
-	}
-
-	if (index < 0)
-	{
-		index += self->size(self);
-	}
-
-	uint32_t count = self->size(self) - 1 - index;
-	uint32_t offset = index * self->_obj_size;
-	uint32_t offset1 = (index + 1) * self->_obj_size;
-	memmove((char*)self->obj + offset, (char*)self->obj + offset1, count * self->_obj_size);
-	self->_size -= 1;
-	return true;
+	return !self->size(self);
 }
 
 bool list_reverse(struct _list* self)
@@ -559,7 +183,7 @@ bool list_init(struct _list* list, uint32_t obj_size)
 	// 2. set function
 	// kernel
 	list->append = list_append;
-	list->at = list_at;
+	list->get = list_get;
 	list->clear = list_clear;
 	list->destory = list_destory;
 	list->empty = list_empty;
diff --git a/datastruct/list.h b/datastruct/list.h
index ab46d29..89885d7 100644
--- a/datastruct/list.h
+++ b/datastruct/list.h
@@ -3,69 +3,43 @@
 
 #include "common.h"
 
-// #define LINK_LIST		1
-// #define LIST				1
-
-#ifdef LINK_LIST
-#define LIST_TEST
-
-#ifdef LIST_TEST
-	typedef int list_data_t;
-#else
-	typedef int list_data_t;
-#endif
-
-typedef struct _list_t
-{
-	list_data_t data;
-	struct _list_t * prev;
-	struct _list_t * next;
-}list_t,*plist_t;
-
-typedef void (*list_data_disp_t)(list_data_t data);
-
-
-bool list_init(plist_t *list);
-void list_destroy(plist_t *list);
-bool list_empty(plist_t list);
-void list_clear(plist_t list);
-bool list_insert_head(plist_t list, list_data_t data);
-bool list_insert_tail(plist_t list, list_data_t data);
-bool list_delete(plist_t list, list_data_t data);
-uint32_t list_count(plist_t list);
-void list_traversal_sequence(plist_t list, list_data_disp_t disp);
-void list_traversal_reversed(plist_t list, list_data_disp_t disp);
-
-extern void list_test(void);
-#endif
-
 #ifdef LIST
 
 struct _list
 {
 	void * obj;
+
 	uint32_t _obj_size;			// 元素大小
 	uint32_t _size;				// 栈大小
 	uint32_t _capacity;			// 总容量
 	uint32_t _ratio;			// 扩展比率
 
 	// kernel
-	bool (*append)(struct _list* self, void* obj);						// 追加对象
-	bool (*insert)(struct _list* self, uint32_t index, void* obj);		// 在列表指定位置，插入对象
-	bool (*pop)(struct _list* self, int index, void* obj);				// 根据索引，删除对象并返回。
-	bool (*remove)(struct _list* self, int index);						// 根据索引，移除对象
+	bool (*append)(struct _list* self, void* obj);						// Append object to the end of the list.
+	bool (*insert)(struct _list* self, int index, void* obj);			// Insert object before index.
+	bool (*pop)(struct _list* self, int index, void* obj);				// Remove and return item at index.
+	
+	int (*index)(struct _list* self, void* obj);						// Return first index of obj. Return -1 if the obj is not present.
+	bool (*remove)(struct _list* self, void *obj);						// Remove first occurrence of obj.
 
-	int (*index)(struct _list* self, void* obj);						// 在列表中，查找数据是否存在，若存在则返回其索引。否则返回-1
-	bool (*at)(struct _list* self, int index, void* obj);				// 根据索引，获取对象
+	bool (*clear)(struct _list* self);									// Remove all items from list.
+
+	bool (*get)(struct _list* self, int index, void* obj);				// 根据索引，获取对象
 	bool (*set)(struct _list* self, int index, void* obj);				// 根据索引，修改对象
 
 	// base
 	uint32_t(*size)(struct _list* self);
-	bool (*clear)(struct _list* self);
 	bool (*empty)(struct _list* self);
 
 	// sort
-	bool (*reverse)(struct _list* self);
+	bool (*reverse)(struct _list* self);		// Reverse *IN PLACE*.
+
+	/**
+		Sort the list in ascending order and return false.
+		The sort is in-place (i.e. the list itself is modified) and stable (i.e. the
+		order of two equal elements is maintained).
+		The reverse flag can be set to sort in descending order.
+	*/
 	bool (*sort)(struct _list* self, uint8_t reserve, int (*compare)(void* obj, void* obj2));
 
 	// free
diff --git a/datastruct/list_test.c b/datastruct/list_test.c
index db62b22..61103fa 100644
--- a/datastruct/list_test.c
+++ b/datastruct/list_test.c
@@ -1,4 +1,4 @@
-#define _CRT_SECURE_NO_WARNINGS 1
+#define _CRT_SECURE_NO_WARNINGS 1		// for vs2022
 #include "list.h"
 
 static void print_num(void* obj)
@@ -28,16 +28,16 @@ static void list_test_num(void)
 	list.print(&list);
 	printf("\n");
 
-	printf("----- remove -----\n");
-	list.remove(&list, 9);
+	printf("----- pop -----\n");
+	list.pop(&list, 9, NULL);
 	list.print(&list);
 	printf("\n");
 
-	list.remove(&list, 0);
+	list.pop(&list, 0, NULL);
 	list.print(&list);
 	printf("\n");
 
-	list.remove(&list, 4);
+	list.pop(&list, 4, NULL);
 	list.print(&list);
 	printf("\n");
 
@@ -55,17 +55,17 @@ static void list_test_num(void)
 	list.print(&list);
 	printf("\n");
 
-	printf("----- at -----\n");
+	printf("----- get -----\n");
 	index = 0;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = %2d\n", index, temp);
 
 	index = 4;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = %2d\n", index, temp);
 
 	index = 9;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = %2d\n", index, temp);
 
 
@@ -92,15 +92,15 @@ static void list_test_num(void)
 
 	printf("----- at like python -----\n");
 	index = -1;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = %2d\n", index, temp);
 
 	index = -6;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = %2d\n", index, temp);
 
 	index = -10;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = %2d\n", index, temp);
 
 	printf("----- set like python -----\n");
@@ -177,16 +177,16 @@ static void list_test_struct(void)
 	list.print(&list);
 	printf("\n");
 
-	printf("----- remove -----\n");
-	list.remove(&list, 9);
+	printf("----- pop -----\n");
+	list.pop(&list, 9, NULL);
 	list.print(&list);
 	printf("\n");
 
-	list.remove(&list, 0);
+	list.pop(&list, 0, NULL);
 	list.print(&list);
 	printf("\n");
 
-	list.remove(&list, 4);
+	list.pop(&list, 4, NULL);
 	list.print(&list);
 	printf("\n");
 
@@ -206,17 +206,17 @@ static void list_test_struct(void)
 
 	printf("----- at -----\n");
 	index = 0;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = ", index);
 	list.print_obj(&temp); printf("\n");
 
 	index = 4;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = ", index);
 	list.print_obj(&temp); printf("\n");
 
 	index = 9;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = ", index);
 	list.print_obj(&temp); printf("\n");
 
@@ -250,17 +250,17 @@ static void list_test_struct(void)
 
 	printf("----- at like python -----\n");
 	index = -1;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = ", index);
 	list.print_obj(&temp); printf("\n");
 
 	index = -6;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = ", index);
 	list.print_obj(&temp); printf("\n");
 
 	index = -10;
-	list.at(&list, index, &temp);
+	list.get(&list, index, &temp);
 	printf("list[%4d] = ", index);
 	list.print_obj(&temp); printf("\n");