How can I write a function in real mode (assembly)

Question

I have been learning how to write bootable programs in assembly x86 in real mode for a couple weeks, but I wasn't able to make any big progress, sice I could't find on my own any free good course in bare metal programming for x86 cpu-s in assembly. Therefore I am attempting to learn through trial and error, but the more I try the more I go wrong. Today I was trying to understand how to handle stack and how to build a function in real mode using AT&T assemby, and I wrote this code, thinking it made sense:

        .code16
        .global init

# PRINT SI
print:
        push    %bp
        mov     %sp, %bp
        sub     $16, %sp
        pusha
        mov     $0xe, %ah
print_char:
        lodsb
        cmp     $0, %al
        je      print_end
        int     $0x10
        jmp     print_char
print_end:
        popa
        mov     %bp, %sp
        pop     %bp
        ret

init:
        mov     $msg, %si
        call    print
        hlt

msg:    .asciz "Test number one..."


        .fill 510-(.-print), 1, 0
        .word 0xaa55

It should print "Test number one..." on the screen, but using qemu it prints just "S" on the screen, like this:

Can someone figure out where did I go wrong and why?