求大佬注释，这个非递归后序遍历求二叉树结点路径的算法有点看不懂

void search(BiTree bt,BiTNode *ch)
{
   
    BiTNode *stack[num];
    int tag[num];
    int i,top;
    int find;
    BiTNode *s;
    find=FALSE;
    top=0;
    s=bt;
    do
    {
        while(s!=NULL)
        {
            top++;
            stack[top]=s;
            tag[top]=0;
            s=s->lchild;
        }
        if(top>0)
        {
            s=stack[top];
            if(tag[top]==1)
            {if(s==ch)
               
                {
                    for(i=1;i<=top;i++)
                        printf("->%c",stack[i]->data);
                    find=TRUE;
                }
                else
                    top--;
                s=stack[top];
            }

            if(top>0 && !find)
            {
                if(tag[top]!=1)
                {
                    s=s->rchild;
                    tag[top]=1;
                }
                else
                    s=NULL;
            }
        }
    }while(!find && top!=0);
}