riscv_asm/libzomutils.s

.text

.globl len
.globl puts
.globl exit

len:
    mv t0, a0
    mv t1, t0

lenloop:
    lb t2, (t1)
    beq t2, x0, lencleanup
    addi t1, t1, 1
    j lenloop

lencleanup:
    sub a0, t1, t0
    ret

puts:
    #here a0 should be the pointer to the string

    #save s2 becuase we are gonna use it
    addi sp, sp, -16
    sd s2, 12(sp)

    #save a0 because we need it later
    mv s2, a0

    #get length because the stdout systemcall needs it in a2
    addi sp, sp, -16     # Allocate stack space
    sd ra, 12(sp)        # Save return address
    jal ra, len
    ld ra, 12(sp)        # Restore return address
    addi sp, sp, 16      # Deallocate stack space
    #a0 should be the length
    mv a2, a0 #stdout expects it in a2

	li a0, 1            # file descriptor = 1 (stdout)
	li a7, 64       # syscall write (64)

    mv a1, s2   #this should still be the pointer to the text

    #restore s2 for the next guy
    ld s2, 12(sp)
    addi sp, sp, 16

    ecall

    ret

exit:
    li a0, 0            # exit code
    li a7, 93           # syscall exit
    ecall