So, I want to create a game of life simulator on the console. For that, I need to move the cursor up so I can rewrite on it and I can do that with \u008d.
I try that on the console:
echo -e "Everyone\n\u008dHi"
This gives me the result:
Hieryone
This is the expected result, and proves that my console accepts that character. But, when I try the exact same thing in NASM,
global _start
segment .text
_start:
;; Print message
mov rax, 1
mov rdi, 1
mov rsi, message
mov rdx, length
syscall
;; Exit
mov rax, 60
mov rdi, 0
syscall
segment .data
message: db "Everyone", 0xa, 0x8d, "Hi"
length: equ $ - message
And run it like,
nasm example.asm -f elf64 -o output.o
ld output.o -o output
./output
I get,
Everyone
�Hi
Why is that? Is there something that changes the way this character is interpreted in my NASM program? Am I missing something in the Unicode? Or is there another alternative that would allow me to move the cursor back? Any help would be useful. (I am on Linux btw)
I suggest you compare it with the hexdump.
$ echo -e "Everyone\n\u008dHi" | hexdump -C
00000000 45 76 65 72 79 6f 6e 65 0a c2 8d 48 69 0a |Everyone...Hi.|
0000000e
$ ./output | hexdump -C
00000000 45 76 65 72 79 6f 6e 65 0a 8d 48 69 |Everyone..Hi|
0000000c
As you see, the difference is whether you have 0xc2 or not (except for newline 0x0a).
In UTF-8, 0x8d must be represented as 0xc2 0x8d.
Therefore, the following modifications will give the expected results.
message: db "Everyone", 0xa, 0xc2, 0x8d, "Hi"