33     struct malloc_mem_chunk_t *prev; // 上一个结点的指针  member
162     new_ck->prev = NULL;  in malloc_enlarge()
183         if (((uint64_t)(ptr->prev) + ptr->prev->length == (uint64_t)ptr))  in malloc_merge_free_chunk()
187             ptr->prev->length += ptr->length;  in malloc_merge_free_chunk()
188             ptr->prev->next = ptr->next;  in malloc_merge_free_chunk()
190                 malloc_free_list_end = ptr->prev;  in malloc_merge_free_chunk()
192                 ptr->next->prev = ptr->prev;  in malloc_merge_free_chunk()
194             ptr = ptr->prev;  in malloc_merge_free_chunk()
211         ck->prev = ck->next = NULL;  in malloc_insert_free_list()
226                     ck->prev = ptr;  in malloc_insert_free_list()
232                     ck->prev = ptr;  in malloc_insert_free_list()
235                     ck->next->prev = ck;  in malloc_insert_free_list()
242                 if (ptr->prev == NULL) // 是第一个项  in malloc_insert_free_list()
245                     ck->prev = NULL;  in malloc_insert_free_list()
247                     ptr->prev = ck;  in malloc_insert_free_list()
252                     ck->prev = ptr->prev;  in malloc_insert_free_list()
254                     ck->prev->next = ck;  in malloc_insert_free_list()
255                     ptr->prev = ck;  in malloc_insert_free_list()
316     if (ck->prev == NULL) // 当前是链表的第一个块  in malloc()
321         ck->prev->next = ck->next;  in malloc()
324         ck->next->prev = ck->prev;  in malloc()
326         malloc_free_list_end = ck->prev;  in malloc()
334         new_ck->prev = new_ck->next = NULL;  in malloc()