Source to src/include/xwin.h

 /*
  * UAE - The Un*x Amiga Emulator
  *
  * Interface to the graphics system (X, SVGAlib)
  *
  * Copyright 1995-1997 Bernd Schmidt
  */

typedef long int xcolnr;

typedef int (*allocfunc_type)(int, int, int, xcolnr *);

extern xcolnr xcolors[4096];

extern int buttonstate[3];
extern int newmousecounters;

extern int graphics_setup (void);
extern int graphics_init (void);
extern void graphics_leave (void);
extern void graphics_subshutdown (int final);
extern int graphics_subinit (void);
extern void handle_events (void);
extern void setup_brkhandler (void);

extern void flush_line (int);
extern void flush_block (int, int);
extern void flush_screen (int, int);

extern int lockscr (void);
extern void unlockscr (void);

extern int debuggable (void);
extern int needmousehack (void);
extern void togglemouse (void);
extern void LED (int);

extern int bits_in_mask (unsigned long mask);
extern int mask_shift (unsigned long mask);
extern unsigned long doMask (int p, int bits, int shift);
extern unsigned long doMask256 (int p, int bits, int shift);
extern void setup_maxcol (int);
extern void alloc_colors256 (int (*)(int, int, int, xcolnr *));
extern void alloc_colors64k (int, int, int, int, int, int);
extern void setup_greydither (int bits, allocfunc_type allocfunc);
extern void setup_greydither_maxcol (int maxcol, allocfunc_type allocfunc);
extern void setup_dither (int bits, allocfunc_type allocfunc);
extern void DitherLine (uae_u8 *l, uae_u16 *r4g4b4, int x, int y, uae_s16 len, int bits) ASM_SYM_FOR_FUNC("DitherLine");

struct vidbuf_description
{
    /* The graphics code has a choice whether it wants to use a large buffer
     * for the whole display, or only a small buffer for a single line.
     * If you use a large buffer:
     *   - set bufmem to point at it
     *   - set linemem to 0
     *   - if memcpy within bufmem would be very slow, i.e. because bufmem is
     *     in graphics card memory, also set emergmem to point to a buffer
     *     that is large enough to hold a single line.
     *   - implement flush_line to be a no-op.
     * If you use a single line buffer:
     *   - set bufmem and emergmem to 0
     *   - set linemem to point at your buffer
     *   - implement flush_line to copy a single line to the screen
     */
    char *bufmem;
    char *linemem;
    char *emergmem;
    int rowbytes; /* Bytes per row in the memory pointed at by bufmem. */
    int pixbytes; /* Bytes per pixel. */
    int width;
    int height;
    int maxblocklines; /* Set to 0 if you want calls to flush_line after each drawn line, or the number of
			* lines that flush_block wants to/can handle (it isn't really useful to use another
			* value than maxline here). */
    int can_double; /* Set if the high part of each entry in xcolors contains the same value
		     * as the low part, so that two pixels can be drawn at once. */
};

extern struct vidbuf_description gfxvidinfo;

/* For ports using tui.c, this should be built by graphics_setup(). */