mirror of
https://github.com/openhwgroup/cvw
synced 2025-02-11 06:05:49 +00:00
33 lines
816 B
ArmAsm
33 lines
816 B
ArmAsm
// sum.s
|
|
// David_Harris@hmc.edu 24 December 2021
|
|
// Add up numbers from 1 to N.
|
|
|
|
// result in s0, i in s1, N in a0, return answer in a0
|
|
//
|
|
// long sum(long N) {
|
|
// long result, i;
|
|
// result = 0;
|
|
// for (i=1; i<=N; i++) result = result + i;
|
|
// return result;
|
|
// }
|
|
|
|
.global sum
|
|
sum:
|
|
addi sp, sp, -16 # make room to save s0 and s1 on the stack
|
|
sd s0, 0(sp)
|
|
sd s1, 8(sp)
|
|
|
|
li s0, 0 # result = 0
|
|
li s1, 1 # i = 1
|
|
for: bgt s1, a0, done # exit loop if i > n
|
|
add s0, s0, s1 # result = result + i
|
|
addi s1, s1, 1 # i++
|
|
j for # repeat
|
|
|
|
done:
|
|
mv a0, s0 # put result in a0 to return
|
|
ld s0, 0(sp) # restore s0 and s1 from stack
|
|
ld s1, 8(sp)
|
|
addi sp, sp, 16
|
|
ret # return from function
|