masked_blit
is Allegro 4 function. It does not exist in Allegro 5.
Here are graphics functions in Allegro 5
al_draw_bitmap_region
is the most similiar function to masked_blit
, but transparency rules are different (8-bit alpha channel vs 1-bit pink color as alpha).
al_convert_mask_to_alpha(ALLEGRO_BITMAP *bitmap, ALLEGRO_COLOR mask_color)
may be useful here.