Experiment 1, experiment 2 and Experiment 3 of assembly language and microcomputer principle: branch program design / loop program design / subroutine design

Experiment 1 Branch programming

The experimental requirements ：

Count the number of negative and non negative numbers in the signed byte array

Experimental code

org 100h

	.MODEL TINY
	.STACK 100
	.DATA 
arr db -10,0,127,-128,63,67,8,-16,1,2
negcnt db 0
poscnt db 0
	.CODE
start: mov ax,@data
	mov ds,ax
	mov es,ax
	
	mov cx,10   ; The array length is 10
	lea bx,arr    ;bx Point to arr
	mov negcnt,0    ; negative 0 individual 
	mov poscnt,0    ; Nonnegative number 0 individual 
	mov dx,0
loopst:	cmp cx,0
	jle loopend
	cmp dx,[bx] ; Compare 0 and bx The size of the number pointed 
	jg label2
	inc poscnt    ; Non negative count 
	jmp exit
label2:	inc negcnt    ; Negative count 
exit:	dec cx
	inc bx
	jmp loopst
loopend:jmp $
	end start
ret

Experiment two Loop programming

The experimental requirements

Bubble sorting method is used to sort the length of 20 Incremental sorting of word data .

Experimental code

org 100h
	.MODEL TINY
	.STACK 100
	.DATA 
arr dw -128,127,-1,0,1,129,-129,32767,-32768,32766,-32767,1,0,1024,-1023,16384,45,-46,-5,6
len equ 20
    .CODE
start: mov ax,@data
	mov ds,ax
	mov es,ax

    mov cx,len-1
loop1:
    push cx
    mov bx,offset arr
loop2:
    mov dx,[bx]
    cmp dx,[bx+2]
    jle next
    xchg dx,[bx+2]
    xchg dx,[bx]
next:
    inc bx
    inc bx
    loop loop2
    pop cx
    loop loop1

    mov ax,4C00H
    jmp $
    end start
ret

Experiment three Subroutine design

The experimental requirements ：

Choose to enter an unsigned integer from the keyboard , Judge whether it is a prime number and display relevant prompt information on the display . The function of judging whether a number is a prime number is realized by subroutine .

org 100h
	.MODEL TINY
	.STACK 100
	.DATA 
	msg1 db 'the number is a prime',0dh,0ah,'$'
	msg2 db 'the number is not a prime',0dh,0ah,'$'
	innum dw 0
	indig db 0 
	divnum db 0
	ten db 10           
	res db 0
	.CODE
start:
	mov ax,@data
	mov ds,ax
	mov es,ax
	call input1;// Input 
	call isp  ;// Judge whether it is a prime 
	mov ah,09h
	cmp res,0;// Not primes 
	je exit3   
	mov dx,offset msg1;// Prime number 
	int 21h
	jmp exit4
exit3:
    mov dx,offset msg2;// Not primes , Output 
    int 21h	
exit4:	jmp $


input1  proc near
	mov ax,0h
	mov innum,0h;// Store complete input data 
label1:
	mov ah,01h
	mov al,02h
	int 21h
	cmp al,'0'
	jl exit
	cmp al,'9'
	jg exit;// It is detected that it is not a number , It indicates that the data input is completed 
	sub al,'0'
	mov indig,al;//indig Represents the single digit of the current number 
	mov ax,innum;// Previously entered data innum*10 Add the current digit , Splice to get the current number 
	mul ten
	mov innum,ax
	mov al,indig
    cbw
	add innum,ax;// The stitching is complete 
	jmp label1;// Enter the next digit 
exit:

	ret        
input1 endp
	  
isp proc near
    mov ax,innum
    cmp ax,2
    jb exit0 ;//0 and 1 Not primes 
    je exit1;//2 Prime number 
    mov divnum,2    ;// The divisor begins with 2
    mov cx,innum
    sub cx,1;//cx Enter a number for -1, Is the maximum value of the cycle 
loop1:
    push ax
    div divnum;//ax/divnum
    cmp ah,0;// Remainder is 0, Is the sum 
    jz exit0
    inc divnum   
    cmp divnum,cx 
    pop ax
    jb loop1
    jge exit1;//2~n-1 I've tried all the numbers , Not enough , Prime number 
exit1:
    mov res,1
exit0:

    ret 
    	
isp endp   
end start 
end