Indicate which parts of the palette have changed. allegro game programming library.
#include <allegro.h>
extern int fli_pal_dirty_from;
extern int fli_pal_dirty_to;
These variables are set by next_fli_frame() to indicate which part of the fli_palette has changed since the last call to reset_fli_variables(). If fli_pal_dirty_from is greater than fli_pal_dirty_to, the palette has not changed, otherwise colors fli_pal_dirty_from to fli_pal_dirty_to (inclusive) have altered. You can use these when updating the hardware palette, to avoid unnecessary calls to set_palette(). Example:
if (fli_pal_dirty_from <= fli_pal_dirty_to) set_palette_range(fli_palette, fli_pal_dirty_from, fli_pal_dirty_to, 1);
fli_palette(3alleg4), reset_fli_variables(3alleg4)