get_color_depth - Returns the current pixel color depth. Allegro game programming library.

       Returns  the  current  pixel  format. This can be very useful to know in order to write generic functions
       which select a different code path internally depending on the color depth being used.

       Note that the function returns whatever value you may have set previously with  set_color_depth(),  which
       can  be  different from the current color depth of the screen global variable. If you really need to know
       the color depth of the screen, use bitmap_color_depth().

       get_color_depth - Returns the current pixel color depth. Allegro game programming library.

set_color_depth(3alleg4), bitmap_color_depth(3alleg4), exrgbhsv(3alleg4)

Allegro                                           version 4.4.3                         get_color_depth(3alleg4)

#include<allegro.h>intget_color_depth(void);