Question

Write in ARM assembly language the following operations without using multiplication instruction:

a) A * 17

b). A * 23

Answer 1

Code:

you can use an arm-*-*-gcc toolchain to get this kind of answers.

Multiplication without use of Mul Instruction: a * 17

$ cat m17.c
int f(int a) {
    return a * 17;
}

$ arm-linux-gnueabihf-gcc -O3 -S m17.c
$ cat m17.s
        <skipped>
f:
    add r0, r0, r0, lsl #4
    bx lr

Multiplication without use of Mul Instruction: a* 23

$ cat m23.c
int f(int a) {
    return a * 23;
}

$ arm-linux-gnueabihf-gcc -O3 -S m23.c
$ cat m23.s
        <skipped>
f:
    add r0, r0, r0, lsl #4
    bx lr