GLFW example

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stefano

Joined: 27 Feb 2020
Posts: 1

stefano 29 Feb 2020, 14:05

I just wrote my first ELF64 file that uses GLFW to create a window Smile

I used as a template the example included with fasm located at './examples/elfexe/dynamic/hello64.asm' and used as reference the example code available at https://www.glfw.org/documentation.html.

Code:

format ELF64 executable 3
entry start

include 'import64.inc'

interpreter '/lib64/ld-linux-x86-64.so.2'
needed 'libc.so.6'
needed 'libGL.so'
needed 'libglfw.so'
import printf,exit,glfwInit,glfwCreateWindow,glfwTerminate,glfwMakeContextCurrent,glfwWindowShouldClose,glClear,glfwSwapBuffers,glfwPollEvents

segment readable executable

start:
        call    [glfwInit]
        cmp     rax,1
        jne     error
        mov     r8,0
        mov     rcx,0
        lea     rdx,[msg]
        mov     rsi,480
        mov     rdi,640
        call    [glfwCreateWindow]
        cmp     rax,0
        je      error
        mov     [window], rax   
        mov     rdi,[window]
        call    [glfwMakeContextCurrent]
waitforclose:
        mov     rdi,[window] ;when using "lea" glfwWindowShouldClose always returned 0
        call    [glfwWindowShouldClose]
        cmp     rax,0
        jne     terminate
        mov     rdi,16384 ;GL_COLOR_BUFFER_BIT
        call    [glClear]
        mov     rdi,[window]
        call    [glfwSwapBuffers]
        call    [glfwPollEvents]
        jmp     waitforclose
error:
        lea     rdi,[emsg]
        xor     eax,eax
        call    [printf]
terminate:
        call    [glfwTerminate] 
quit:
        call    [exit]

segment readable writeable

msg db 'a window',0
emsg db 'error',0xa,0
window dq ?

I tried the X11 examples available in the forum but I was getting "segmentation fault" related to 'libxcb.so' and I couldn't identify the issue. That's why I decided to try with that example once I understood what I had to do.

Thanks to the videos that Tomasz uploaded to Youtube I've been able to understand a lot of things that I hadn't until now. I hope he keeps uploading new content!

Any feedback about the code is appreciated. It helps me to learn something new and understand better what's going on Laughing

Edit by revolution: Fix documentation link

29 Feb 2020, 14:05

april.asm

Joined: 10 Nov 2025
Posts: 3
Location: Hell

april.asm 10 Nov 2025, 18:46

This is pretty cool

10 Nov 2025, 18:46

macgub

Joined: 11 Jan 2006
Posts: 360
Location: Poland

macgub 11 Nov 2025, 17:25

I compile and try execute above. I get failed when I run it.Gdb tells me: error while loading shared libraries: libglfw.so: cannot open shared object file: No such file or directory. I tried install missing files but get troubles with correctly specifying appropriate libs. This time Software manager wasn't helpful.
I search for best way to supply libs which are needed. I use Mint Mint 22 Wilma.

11 Nov 2025, 17:25

macomics

Joined: 26 Jan 2021
Posts: 1199
Location: Russia

macomics 11 Nov 2025, 20:46

I also tried this example on Calculate Linux. I needed to add media-libs/glfw via emerge and everything worked.

The green background is not a mistake. I just added glClearColor(0.0f, 1.0f, 0.0f, 1.0f);

Description:
Filesize:	74.77 KB
Viewed:	117 Time(s)

11 Nov 2025, 20:46

chastitywhiterose

Joined: 13 Oct 2025
Posts: 27

chastitywhiterose 13 Nov 2025, 04:16

I have done a little bit of OpenGL from the C interface. I could do legacy OpenGL but not the modern core stuff. But seeing your post led me to the idea that theoretically when using something open source like GLFW, the Assembly code would be mostly portable between Linux and Windows as long as they were both running on Intel CPUs.

13 Nov 2025, 04:16

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