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# print_b.s
.global print

print:
    mov $0, %rcx
    jmp loop

loop:
    (略)
    inc %rcx
    cmp $0x10, %rcx
    je loop
    ret

コンソール
$ gcc -nostdlib substart.s print_b.s hello.c -o hello
$ ./hello

実行結果
aaa
H
Hello World

# substart.s
.global _start

_start:
    call main
        mov $60, %eax           # exit
        xor %rdi, %rdi          # mov $0, %rdi
        syscall

// hello.c
void print(const void* c);

int main(void) {
        char str[] = "Hello World";
        print(&"a");
        print(&"a");
        print(&"a");
        print(&"\n");
        print(&str);
        print(&"\n");
        for (int i = 0; i < sizeof(str) / sizeof(char); i++) {
                print(&str[i]);
        }
        print(&"\n");
        return 0;
}

print_b.s: Assembler messages:
print_b.s:13: Error: invalid instruction suffix for `push'
print_b.s:15: Error: invalid instruction suffix for `pop'