Question

3) Write an assembly program that is algorithmically equivalent to the following C++ code. Treat the variable y as a short int (16 bits) 1 int y; 2 for (int x = 2; x <= 20; x = x + 2) { 3 ¡f (x < 18) { 4 5 у 24 6 else f 7 8 9

avr assembly please

Answer 1

Here I am converting C++ code to assembly code,see below.

CPP_Code:-

#include<bits/stdc++.h>

int main()

{

short int y;

for(int x=2;x<=20;x=x+2)

{

if(x<10)

{

y=2*(x-1)+3;

}

else

{

y=x+5;

}

}

}

Assembly Code:-

main:

str fp, [sp, #-4]!

add fp, sp, #0

sub sp, sp, #12

mov r3, #2

str r3, [fp, #-8]

.L5:

ldr r3, [fp, #-8]

cmp r3, #20

bgt .L2

ldr r3, [fp, #-8]

cmp r3, #9

bgt .L3

ldr r3, [fp, #-8]

sub r3, r3, #1

lsl r3, r3, #16

lsr r3, r3, #16

lsl r3, r3, #1

lsl r3, r3, #16

lsr r3, r3, #16

add r3, r3, #3

lsl r3, r3, #16

lsr r3, r3, #16

strh r3, [fp, #-10] @ movhi

b .L4

.L3:

ldr r3, [fp, #-8]

lsl r3, r3, #16

lsr r3, r3, #16

add r3, r3, #5

lsl r3, r3, #16

lsr r3, r3, #16

strh r3, [fp, #-10] @ movhi

.L4:

ldr r3, [fp, #-8]

add r3, r3, #2

str r3, [fp, #-8]

b .L5

.L2:

mov r3, #0

mov r0, r3

add sp, fp, #0

ldr fp, [sp], #4

bx lr

__static_initialization_and_destruction_0(int, int):

push {fp, lr}

add fp, sp, #4

sub sp, sp, #8

str r0, [fp, #-8]

str r1, [fp, #-12]

ldr r3, [fp, #-8]

cmp r3, #1

bne .L9

ldr r3, [fp, #-12]

ldr r2, .L10

cmp r3, r2

bne .L9

ldr r0, .L10+4

bl std::ios_base::Init::Init() [complete object constructor]

ldr r2, .L10+8

ldr r1, .L10+12

ldr r0, .L10+4

bl __aeabi_atexit

.L9:

nop

sub sp, fp, #4

pop {fp, lr}

bx lr

.L10:

.word 65535

.word _ZStL8__ioinit

.word __dso_handle

.word _ZNSt8ios_base4InitD1Ev

_GLOBAL__sub_I_main:

push {fp, lr}

add fp, sp, #4

ldr r1, .L13

mov r0, #1

bl __static_initialization_and_destruction_0(int, int)

sub sp, fp, #4

pop {fp, lr}

bx lr

.L13:

.word 65535

Brief Explanation:-

I am converting CPP code to Assembly code,where as the y consider as the short int(16 bits).Once you can check it.

Thank you..!!