Question

1. Implement the following expression in assembly language:

                                                BX = –val2 + 7 - (- val3 + val1) * 2

• Assume that val1, val2, and val3 are 8-bit integer variables
• Initialize val1 with 12, val2 with 9, and val3 with 2
• You are only allowed to use 16-bit registers to hold intermediate results, whenever needed.
• Use ONLY mov, add, sub, movzx, movzx, or neg instructions whenever needed.
• Use the debugger to verify your answer.

Please answer using this format for code:

.386

.model flat, stdcall

.stack 4096

ExitProcess PROTO, dwExitCode:DWORD

.data

...(please initialize the variables)...

.code

...(insert code here)...

INVOKE ExitProcess,0

main ENDP

END main

Answer 1

.386
.model flat,stdcall
.stack 4096
ExitProcess proto,dwExitCode:dword
.data
val1 sbyte 0        ;intialize val1
val2 sbyte 0        ;intialize val2
val3 sbyte 0        ;intialize val3
result sword 0      ;intialize result
.code
main proc
mov val1,12         ;val1 = 12
mov val2,9          ;val2 = 9
mov val3,2          ;val3 = 2

mov ax,0
mov bx,0
mov cx,0
mov dx,0


movzx dx,val2       ;dx = val2
neg dx              ;dx = -val2
add dx,7            ;dx = -val2 + 7

movzx ax,val3       ;ax = val3
neg ax              ;ax = -val3 
movzx cx,val1       ;cx = val1
add ax,cx           ;ax = -val3 + val1
add dx,ax           ;dx = -val2 + 7 -val3 + val1

mov ax,dx           ;ax = dx
mul 2               ;ax = -val2 + 7 -val3 + val1 * 2
mov bx,ax           ;bx = result, = -val2 + 7 -val3 + val1 
invoke ExitProcess,0
    main endp
end main