tut_machine.m.txt

这是一个用Matlab描述的关于Ｘ＋Ｙ的图灵机程序

function Tut_Machine()
global buffer        %建立数组
global pos       %磁头位置
global status 
global unit
global data
global s_flag
global ox
global oy
global h_data
global s_text
global size
global inc
global disp_sta
global disp_end
global trans_arry
global buf_end
global ysize
size=18 %数组长度会变，但显示的永远是下标为1:size的内容
ysize=floor(size/3)  %取整数部分
inc=floor(size/3)  %数组不够时增加的数目

trans_array=[struct('write_data',0,'direction',1,'new_status',1),struct('write_data',1,'direction',1,'new_status',2),struct('write_data',1,'direction',0,'new_status',7);
             struct('write_data',0,'direction',1,'new_status',2),struct('write_data',1,'direction',1,'new_status',2),struct('write_data',2,'direction',1,'new_status',3);
             struct('write_data',0,'direction',1,'new_status',3),struct('write_data',3,'direction',3,'new_status',-1),struct('write_data',0,'direction',0,'new_status',4);
             struct('write_data',0,'direction',0,'new_status',4),struct('write_data',4,'direction',3,'new_status',-1),struct('write_data',2,'direction',0,'new_status',5);
             struct('write_data',1,'direction',0,'new_status',5),struct('write_data',0,'direction',0,'new_status',6),struct('write_data',5,'direction',3,'new_status',-1);
             struct('write_data',0,'direction',0,'new_status',6),struct('write_data',1,'direction',0,'new_status',6),struct('write_data',2,'direction',1,'new_status',1);
             struct('write_data',2,'direction',0,'new_status',7),struct('write_data',6,'direction',3,'new_status',-1),struct('write_data',2,'direction',3,'new_status',-1)]

bin_num=['1','0','0','0']   %存储自变量的二进制数

%对窗口初始化,包括画矩阵，对每个待显示字符赋给句柄
axis([0,size,0,ysize])   
hold on
Y=3
ox=0.3;oy=0.5; %分别是数字位置的偏移
for i=1:size
unit(i)=rectangle('Position',[i-1,Y,1,1])
h_data(i)=text(i+ox-1,Y+oy,' ')
end

%对buffer数组初始化
buf_end=size  
disp_sta=1
disp_end=size
buffer=init_space(size)     
pos=floor(size/2)
for i=1:length(bin_num) 
   buffer(pos)=bin_num(i)
   pos=pos+1
end
pos=floor(size/2)  %初始化后,指示变量的首位

%从头到尾显示所有的数字
for k=disp_sta:disp_end   %从头到尾显示所有的数字
    if strcmp(buffer(k),'2')==1 %如果是2,显示为B
      set(h_data(k),'string','B')
  else
      set(h_data(k),'string',buffer(k))
  end
end
pause %进入键盘主控状态
status=1
s_text=text(10,5,' ')
%set(s_text,'String','status:S1')
while(status>0)
    st=strcat('status:S',int2str(status))
    set(s_text,'String',st)
    r_data=str2num(buffer(pos))  %读数据
    write_data=trans_array(status,r_data+1).write_data
    move_direction=trans_array(status,r_data+1).direction
    write(write_data)
    pause(0.1)
    if move_direction==0
        move_left
    elseif move_direction==1
        move_right
    end
    status=trans_array(status,r_data+1).new_status
end

stop=0 %控制循环结束
flag=0 %标记是否需要重新显示
%最左端值不为空,则往右移 
if (strcmp(buffer(disp_sta),'2')==0)&(disp_sta>1) 
    flag=1
    k=disp_sta-1
    while (k>=1)&( ~stop) 
        if strcmp(buffer(k),'2')==0 
            stop=1
        end
        if( ~stop) 
            k=k-1  
        end
    end 
       m_bits=disp_sta-k-1
       disp_sta=disp_sta-m_bits
       disp_end=disp_end-m_bits
end
%最右端值不为空,则往左移
if (strcmp(buffer(disp_end),'2')==0)&(disp_end<buf_end)
    flag=1
    k=disp_end+1    
    while (k<=buf_end)&( ~stop) 
        if strcmp(buffer(k),'2')==0 %查找最右端第一个空值的位置
            stop=1
        end
        if( ~stop) 
            k=k+1  
        end
    end
       m_bits=k-1-disp_end   
      disp_sta=disp_sta+m_bits
       disp_end=disp_end+m_bits
end
if (flag>0)   %最左端和最右端如果有从头到尾显示所有的数字
    c=2
   for k=disp_sta:disp_end  
       f=1
    if strcmp(buffer(k),'2')==1 %如果是2,显示为B
      set(h_data(k-disp_sta+1),'string','B')
    else
      set(h_data(k-disp_sta+1),'string',buffer(k))
    end
  end  
end

function space=init_space(num)  %初始化数组
 space(1:num)='2'

function write(x)
global buffer
global pos
global h_data
global disp_sta
 buffer(pos)=int2str(x);
 switch x
   case 0
     set(h_data(pos-disp_sta+1),'string','0')
   case 1
    set(h_data(pos-disp_sta+1),'string','1')
   case 2
    set(h_data(pos-disp_sta+1),'string','B')
  end
end

function r=read()
global pos
global buffer
r=str2num(buffer(pos))

function move_left()
global pos
global disp_sta
global disp_end
global size
global h_data
global buffer
global buf_end
global inc
global inc_buffer 
if(pos>disp_sta) pos=pos-1
else
  if(pos>1)  %pos==disp_sta的情况
     disp_sta=disp_sta-inc
     disp_end=disp_end-inc
     pos=pos-1
  else      
  inc_buffer(1:inc)='2'
  buffer=[inc_buffer,buffer]     %每次pos=1时,就增加数组长度,两边各增加inc_buffer个单位
  buf_end=buf_end+inc
  disp_sta=1
  disp_end=disp_sta+size-1
  pos=inc+pos-1
  end
  
 for k=disp_sta:disp_end   %从头到尾显示所有的数字
    if strcmp(buffer(k),'2')==1 %如果是2,显示为B
      set(h_data(k-disp_sta+1),'string','B')
    else
      set(h_data(k-disp_sta+1),'string',buffer(k))
    end
 end                
end
    
function move_right()
global pos
global disp_sta
global disp_end
global size
global h_data
global buffer
global buf_end
global inc
global inc_buffer 
if(pos<disp_end) pos=pos+1
else
    if pos<buf_end
    pos=pos+1
    disp_sta=disp_sta+inc
    disp_end=disp_end+inc
    else    %如果pos达到buf_end,就要扩充数组
    inc_buffer(1:inc)='2'
    buffer=[buffer,inc_buffer] 
    buf_end=buf_end+inc
    %pos=pos+inc+1
    disp_end=buf_end
    disp_sta=disp_end-size+1
    end
 for k=disp_sta:disp_end   %从头到尾显示所有的数字
    if strcmp(buffer(k),'2')==1 %如果是2,显示为B
      set(h_data(k-disp_sta+1),'string','B')
    else
      set(h_data(k-disp_sta+1),'string',buffer(k))
    end
 end     
end