Looking for help with an ARM assembly program. The instructions are as follows:
ID: 3543597 • Letter: L
Question
Looking for help with an ARM assembly program. The instructions are as follows:
A prime number n is a natural number (i.e. a non-negative integer) which is greater than
1 and is not divisible by any other natural number other than 1 and n. In other words, n has
no non-trivial factors other than 1 and n. So for example, 2 is the smallest prime number.
To test whether a natural number n is a prime number or not, you can set up a loop to test
every natural number between 1 and n (i.e. natural numbers from 2 to n 1) one by one
to see whether n is divisible by any of them and count the number of non-trivial factors for
n you have seen in the whole process. If n is not divisible by any of them, the number of
non-trivial factors for n is 0 and n is a prime number; otherwise n is not a prime number.
Assignment
You are to nd all prime numbers between 1 and n, where n is entered by the user. Your
program should:
prompt the user to input a natural number n,
determine and display all the prime numbers between 1 and n in increasing order, and
print the number of primes found between 1 and n.
Your program must have at least two functions:
isprime should accept one parameter, x and return 0 or 1, indicating whether or not x is
prime.
divide should accept two parameters, x and y and should return the quotient and remainder
(as two separate integers) found by dividing x by y.
Also the divide function is as follows and must be used as such in a seperate file:
.text
.globl divide
divide: mov r2, r1 @move divisor (y) to r2
mov r1, r0 @move dividend (x) to r1
mov r0, #0 @clear r0 to accumulate result
mov r3, #1 @set bit 0 in r3
start: cmp r2, r1 @y < x?
movls r2, r2, lsl#1 @shift y left until y >= x
movls r3, r3, lsl#1 @also shift r3 left until y >= x
bls start @keep shifting until y >= x
loop: cmp r1, r2 @carry set if r1>r2
subcs r1, r1, r2 @if r1>r2 then r1 -= r2
addcs r0, r0, r3 @if r1>r2 then r0 += r3
movs r3, r3, lsr#1 @shift r3 right
movcc r2, r2, lsr#1 @if r3 > 0 then shift r2 right
bcc loop @if r3 == 0 then we are done
mov pc, lr @quotient is in r0, and
@remainder is in r1
.end
Explanation / Answer
Is prime function:
INPUT "Choice ",R9
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