Question

In x86 architecture, write an assembly program for the following:

Xarray is an unsigned array of bytes. Yarray is a signed array of words that has same number of elements as Xarray. Zarray is an uninitialized signed array of doublewords. Write a program that adds each element of Xarray to the corresponding element in Yarray and stores the result as an element in Zarray.

Answer 1

ANSWER :-

Assembly program

DATA SEGMENT
     XARRAY DB 36H,55H,27H,42H  
     ;initialize array with 1 byte size of elements
     YARRAY DW 63H,76H,82H,48H
     ;initialize array with 2 byte size of elements
     ZARRAY DD 70H,85H,91H,98H
     ;declaring an array to save the result with size of 4 bytes                                
ENDS

CODE SEGMENT 
    ASSUME DS:DATA CS:CODE
    ;DATA and CODE are the assumed names given to data segment and code segment            respectively

START:
      MOV AX,DATA
      ;data is moved to AX register which helps in moving data to data segment
      MOV DS,AX
      ;data is moved from AX register to data segment
      LEA SI,XARRAY
      ;load effective address from array variable to register
      LEA DI,YARRAY
      ;load effective address from array variable to register
      LEA BX,ZARRAY
      ;load effective address from array variable to register
      MOV CX,5
      ;the value 5 is moved to register which helped to create a loop of 5 iterations 
LOOP1:      
       MOV AL,[SI]                          
       ;move the value from SI register to AL register
       ADD AL,[DI]
       ;add the value from DI register to AL register and store the value in AL
       MOV [BX],AL           
       ;move the value from AL register to BX register
       INC BX
       ;increment of address
       INC SI
       ;increment of address
       INC DI 
       ;increment of address     
       LOOP LOOP1   
       ;the loop continuous depending on CX register value
     
      MOV AH,4CH
      INT 21H     
      ;the above two instructions are used to exit
ENDS
END START