SDL_WM_SetIcon (3) Linux Manual Page
SDL_WM_SetIcon – Sets the icon for the display window.
Synopsis
#include "SDL.h" void SDL_WM_SetIcon(SDL_Surface *icon, Uint8 *mask);
Description
Sets the icon for the display window. Win32 icons must be 32×32.This function must be called before the first call to SDL_SetVideoMode.
It takes an icon surface, and a mask in MSB format.
If mask is NULL, the entire icon surface will be used as the icon.
Example
SDL_WM_SetIcon(SDL_LoadBMP("icon.bmp"), NULL);