汇编语言教程第5章

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,循环程序设计,分支程序设计,第5章 循环与分支程序设计,分支结构 子程序结构,程序结构：,复合结构：多种程序结构的组合,顺序结构 循环结构,编制汇编语言程序的步骤：,(1),分析题意，确定算法,(2),根据算法画出程序框图,(3),根据框图编写程序,(4),上机调试程序,1.循环程序设计,DO-WHILE,结构,DO-UNTIL,结构,控制条件,初始化,循环体,Y,N,控制条件,初始化,循环体,Y,N,初始化,：,设置循环的初始状态,循环体,：,循环的工作部分及修改部分,控制条件,：,计数控制,特征值控制,地址边界控制,BX,1,2,3,4,例：把,BX,中的二进制数以十六进制的形式显示在屏幕上,mov ch,4,rotate:,mov cl,4,rol bx,cl,mov,al,bl,and al,0fh,add al,30h,;09 ASCII 30H39H,cmp,al,3ah,jl printit,add al,7h,;AF ASCII 41H46H,printit,:,mov,dl,al,mov,ah,2,int,21h,dec ch,jnz,rotate,mov bx,0,newchar,:,mov,ah,1 ；,键盘输入,int,21h,sub al,30h,jl,exit ;,9,退出,cbw,xchg,ax,bx,mov cx,10,mul cx,xchg,ax,bx,add,bx,ax,jmp newchar,exit:,例：从键盘接收十进制数并存入,BX,(010)+1)10+2)10+5,1 2 5,31 32 35,mov bx,0,newchar,:,mov,ah,1,；,键盘输入,int,21h,sub al,30h,jl,exit,;,0,退出,cmp,al,10,jl,add_to,sub al,27h,;af,cmp,al,0ah,jl,exit,;,f,退出,add_to:,mov cl,4,shl bx,cl,mov,ah,0,add,bx,ax,jmp newchar,exit:,例：从键盘接收十六进制数并存入,BX,1 a f,31 61 66,(0,16)+1),16+0,a),16+0f,x,dw,?,array_head,dw,3,5,15,23,37,49,52,65,78,99,array_end,dw,105,n,dw,32,例：将正数,n,插入一个已整序的正数字数组,mov,ax,n,mov,array_head-2,0ffffh,mov si,0,compare:,cmp,array_end,si,ax,jle,insert,mov bx,array_end,si,mov,array_end,si,+2,bx,sub,si,2,jmp,short compare,insert:,mov,array_end,si,+2,ax,3,5,15,23,37,49,52,65,78,99,105,32,-1,array_head,array_end,n,x,例:,将首地址为,A,的字数组从小到大排序,（气泡算法，多重循环）,32,85,16,15,8,序号 地址 数,比 较 遍 数,1,2,3,4,1,A 32,2 A+2 85,3 A+4 16,4 A+6 15,5 A+8 8,32,16,15,8,85,16,15,8,32,85,15,8,16,32,85,8,15,16,32,85,mov cx,5,;,元素个数,dec cx,;,比较遍数,loop1:,mov di,cx,;,比较次数,mov bx,0,loop2:,mov,ax,A,bx,;,相邻两数,cmp,ax,A,bx,+2,;,比较,jle,continue,xchg,ax,A,bx,+2,;,交换位置,mov,A,bx,ax,continue:,add,bx,2,loop loop2,mov cx,di,loop loop1,2.分支程序设计,case 1 case 2 case n,?,?,case 1 case 2 case n,CASE,结构,IF-THEN-ELSE,结构,(1)逻辑尺控制,(2)条件控制,(3)地址跳跃表,（值与地址有对应关系的表）,例：有数组,x(x1,x2,x10),和,y(y1,y2,y10),，,编程计算,z,(z1,z2,z10),z1=x1 +y1,z2=x2 +y2,z3=x3 -y3,z4=x4 -y4,z5=x5 -y5,z6=x6 +y6,z7=x7 -y7,z8=x8 -y8,z9=x9 +y9,z10=x10+y10,逻辑尺：,0 0 1 1 0 1 1 1 0 0,1 减法,0 加法,x,dw,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,y,dw,y1,y2,y3,y4,y5,y6,y7,y8,y9,y10,z,dw,z1,z2,z3,z4,z5,z6,z7,z8,z9,z10,logic_rule,dw,00dch ;0000,0000,1101,1100,mov bx,0,mov cx,10,mov dx,logic_rule,next:,mov,ax,x,bx,shr dx,1,jc,subtract,add ax,y,bx,jmp,short result,;,向前引用,subtract:,sub ax,y,bx,result:,mov,z,bx,ax,add,bx,2,loop next,data segment,array,dw,12,11,22,33,44,55,66,77,88,99,111,222,333,number,dw,55,low_,idx dw,?,high_,idx dw,?,data ends,例：折半查找算法,12,11,22,33,44,55,66,77,88,99,111,222,333,0,1,2,3,4,5,6,7,8,9,10,11,12,(ax)=55,low_,idx,1,1,4,5,high_,idx,12,5,5,5,(,si,)=0ah,Cf,=0,(ax)=90,low_,idx,1,7,7,8,9,high_,idx,12,12,8,8,8,(,si,)=10h,Cf,=1,折半算法1,lea,di,array,mov,ax,number,;,要查找数,cmp,ax,di,+2,;(ax),与第一个元素比较,ja chk,_last,lea,si,di,+2,je,exit,;(ax),第一个元素,找到退出,stc,jmp,exit,;(ax),最后一个元素,未找到退出,算法1,compare:,cmp,ax,bx,+,si,je,exit,ja,higher,dec cx,mov,high_,idx,cx,jmp,mid,higher:,inc,cx,mov,low_,idx,cx,jmp,mid,no_match:,stc,exit:,search:,mov,low_,idx,1,mov bx,di,;,个数,mov,high_,idx,bx,mov bx,di,mid:,mov cx,low_,idx,mov dx,high_,idx,cmp cx,dx,ja,no_match,add,cx,dx,shr cx,1,mov si,cx,shl si,1,12,11,22,33,44,55,66,77,88,99,111,222,333,0,1,2,3,4,5,6,7,8,9,10,11,12,(ax)=55,di,12,6,10,si,12,6,4,(,si,)=0ah,(,di,)=0ah,Cf,=0,(ax)=90,di,12,18,14,16,si,12,6,4,2,(,si,)=2,(,di,)=10h,Cf,=1,折半算法2,算法2,idx,_ok:,shr si,1,test,si,1,jz,sub_,idx,inc,si,sub_,idx,:,sub,di,si,jmp,short compare,higher:,cmp si,2,je,no_match,shr si,1,jmp,short even_,idx,all_done:,mov si,di,exit:,search:,mov si,di,even_,idx,:,test,si,1,jz,add_,idx,inc,si,add_,idx,:,add,di,si,compare:,cmp,ax,di,je,all_done,ja,higher,cmp si,2,jne idx,_ok,no_match:,stc,jmp,exit,例：根据,AL,寄存器中哪一位为 1（从低位到高位），,把程序转移到 8 个不同的程序分支,branch_table,dw,routine1,dw,routine2,dw,routine3,dw,routine4,dw,routine5,dw,routine6,dw,routine7,dw,routine8,cmp,al,0,;AL,为逻辑尺,je,continue,lea,bx,branch_table,L:,shr,al,1,;,逻辑右移,jnc,add1,jmp,word,ptr,bx,;,段内间接转移,add1:add,bx,type branch_table ；add,bx,2,jmp,L,continue:,routine1:,routine2:,（,寄存器间接寻址,）,（,寄存器相对寻址,）,cmp,al,0,je,continue,mov si,0,L:,shr,al,1,;,逻辑右移,jnc,add1,jmp,branch_table,si,;,段内间接转移,add1:,add,si,type branch_table,jmp,L,continue:,routine1:,routine2:,（,基址变址寻址,）,cmp,al,0,je,continue,lea,bx,branch_table,mov si,7*type branch_table,mov cx,8,L:,shl,al,1,;,逻辑左移,jnc,sub1,jmp,word,ptr,bx,si,;,段内间接转移,sub1:sub,si,type branch_table,;(,si,)-2,loop L,continue:,routine1:,routine2:,第5章作业,Page 193,5.5 5.7,5.12,5.18,