33     struct malloc_mem_chunk_t *prev; // 上一个结点的指针  member
161     new_ck->prev = NULL;  in malloc_enlarge()
182         if (((uint64_t)(ptr->prev) + ptr->prev->length == (uint64_t)ptr))  in malloc_merge_free_chunk()
186             ptr->prev->length += ptr->length;  in malloc_merge_free_chunk()
187             ptr->prev->next = ptr->next;  in malloc_merge_free_chunk()
189                 malloc_free_list_end = ptr->prev;  in malloc_merge_free_chunk()
191                 ptr->next->prev = ptr->prev;  in malloc_merge_free_chunk()
193             ptr = ptr->prev;  in malloc_merge_free_chunk()
210         ck->prev = ck->next = NULL;  in malloc_insert_free_list()
225                     ck->prev = ptr;  in malloc_insert_free_list()
231                     ck->prev = ptr;  in malloc_insert_free_list()
234                     ck->next->prev = ck;  in malloc_insert_free_list()
241                 if (ptr->prev == NULL) // 是第一个项  in malloc_insert_free_list()
244                     ck->prev = NULL;  in malloc_insert_free_list()
246                     ptr->prev = ck;  in malloc_insert_free_list()
251                     ck->prev = ptr->prev;  in malloc_insert_free_list()
253                     ck->prev->next = ck;  in malloc_insert_free_list()
254                     ptr->prev = ck;  in malloc_insert_free_list()
315     if (ck->prev == NULL) // 当前是链表的第一个块  in malloc()
320         ck->prev->next = ck->next;  in malloc()
323         ck->next->prev = ck->prev;  in malloc()
325         malloc_free_list_end = ck->prev;  in malloc()
333         new_ck->prev = new_ck->next = NULL;  in malloc()