Assembly Language Concepts using ARM
Q. 1 | Convert the following C program to ARM assembly. Store the integer, i , in register r 0.
Assume that the starting address of array a is saved in register r 1, and the starting address of
array b is saved in register r 2.
int i;
int b[500];
int a[500];
for(i=0; i < 500; i++) {
b[i] = a[a[i]];
}
Q. 2 | Write an ARM assembly instruction code to count the number of
1's in a 32 bit number.
Soln: l0:
and r1, r0, r3
mov r0, r0, lsl #1
cmp r1, #0
addne r4, r4, #1
cmp r0, #0
bne l0
mov pc, lr
count:
mov r4, #0
mov r0, #1
bl l0
Q. 3 | Design a ARM language program that examines a 32-bit value stored in r1 and counts the
number of contiguous sequences of 1s. For example, the value:
01110001000111101100011100011111
Soln :
l0:
cmp r4, #0
moveq r4, #1
addeq r2, r2, #1
mov pc, lr
l1:
and r3, r1, r0
cmp r3, #0
stmfd sp!, {lr}
