Address "warning: passing arguments to a function without a prototype is deprecated in all versions of C and is not supported in C2x"

* Update struct DevRec methods to take a "void *" parameter
   since they get called with different xxxInterface records
   depending on whether they are a keyboard, mouse, or display.
   Introduce GenericReturnVoid method implementation for use
   where needed with DevRec methods. (see mouseif.c)

 * Cast functions implementing DevRec methods as appropriate to match
   the method signature.

 * Update struct DspInterfaceRec methods cleardisplay,
   bitblt_to_screen, mouse_invisible, and mouse_visible to declare
   the parameters they require and all return unsigned long results
   (though it's not clear that this is actually the correct type).
   Requires updating dosmouse.c method implementations.

 * Update GenericReturnT and GenericPanic method implementations
   to have the signature required by the method slots they
   are used in.

 * Correct DOS-only section with incorrect arguments to device.exit
   call for the mouse.

 * Use include "dspifdefs.h" for prototypes for GenericReturnXXX method
   implementations.

src/dosmouse.c

@@ -280,7 +280,7 @@ void docopy(int newx, int newy)
 #endif /* NEWBITBLT */
 }
 
-dostaking_mouse_up(int newx, int newy)
+unsigned long dostaking_mouse_up(int newx, int newy)
 {
   /* save hidden bitmap */
 
@@ -329,6 +329,7 @@ dostaking_mouse_up(int newx, int newy)
 
   (currentdsp->bitblt_to_screen)(currentdsp, DisplayRegion68k, currentmouse->Cursor.Last.x,
                                  currentmouse->Cursor.Last.y, w, h);
+  return (T);
 }
 
 dostaking_mouse_down(DspInterface dsp, IOPAGE *iop)
@@ -357,6 +358,7 @@ dostaking_mouse_down(DspInterface dsp, IOPAGE *iop)
 
   (dsp->bitblt_to_screen)(dsp, DisplayRegion68k, currentmouse->Cursor.Last.x,
                           currentmouse->Cursor.Last.y, w, h);
+  return (T);
 }
 
 /************************************************************************/

src/dspif.c

@@ -82,9 +82,10 @@ void make_dsp_instance(DspInterface dsp, char *lispbitmap, int width_hint, int h
 /* Utility function that just returns T                              */
 /*                                                                   */
 /*********************************************************************/
-unsigned long GenericReturnT(void) { return (T); }
-
-void GenericPanic(DspInterface dsp) {
+unsigned long GenericReturnT(void *d) { (void)d; return (T); }
+void GenericReturnVoid(void *d) {(void)d; return; }
+void GenericPanic(void *d) {
+  (void)d;
   TPRINT(("Enter GenericPanic\n"));
   fprintf(stderr, "Panic! Call to uninitialized display slot!");
   exit(0);

src/initkbd.c

@@ -229,7 +229,7 @@ void init_keyboard(int flg) /* if 0 init else re-init */
 
 void device_before_exit(void) {
 #if   DOS
-  (currentmouse->device.exit)(currentmouse, currentdsp);
+  (currentmouse->device.exit)(currentmouse);
   (currentkbd->device.exit)(currentkbd);
 #endif /* SUNDISPLAY DOS*/
   display_before_exit();

src/kbdif.c

@@ -15,6 +15,7 @@
 #include "lispemul.h"
 #include "dbprint.h"
 #include "devif.h"
+#include "dspifdefs.h"
 
 KbdInterfaceRec curkbd;
 KbdInterface currentkbd = &curkbd;
@@ -23,7 +24,6 @@ KbdInterface currentkbd = &curkbd;
 extern void Kbd_event(void);
 extern void EnterDosKbd(void);
 extern void ExitDosKbd(void);
-extern unsigned long GenericReturnT(void);
 #endif /* DOS */
 
 void make_kbd_instance(KbdInterface kbd) {

src/mouseif.c

@@ -21,6 +21,7 @@ MouseInterface currentmouse = &curmouse;
 #ifdef DOS
 #include <dos.h>
 #include "lispemul.h"
+#include "dspifdefs.h"  /* for GenericReturnVoid */
 
 int nomouseflag = FALSE;
 extern DLword *Lisp_world;
@@ -31,7 +32,6 @@ extern void EnterDosMouse(void);
 extern void ExitDosMouse(void);
 extern void DosMouseAfterRaid(void);
 extern void DosMouseBeforeRaid(void);
-extern unsigned long GenericReturnT(void);
 extern void ThreeButtonHandler(void);
 extern void TwoButtonHandler(void);
 #endif /* DOS */
@@ -67,10 +67,10 @@ void make_mouse_instance(MouseInterface mouse)
 
   int NumberOfButtons;
   if (nomouseflag) {
-    mouse->device.enter = &GenericReturnT;
-    mouse->device.exit = &GenericReturnT;
-    mouse->device.before_raid = &GenericReturnT;
-    mouse->device.after_raid = &GenericReturnT;
+    mouse->device.enter = GenericReturnVoid;
+    mouse->device.exit = GenericReturnVoid;
+    mouse->device.before_raid = GenericReturnVoid;
+    mouse->device.after_raid = GenericReturnVoid;
     mouse->device.active = FALSE;
     NumberOfButtons = 3;
   } else {

src/vesainit.c

@@ -27,6 +27,7 @@
 #include <graph.h>
 
 #include "dbprint.h"
+#include "dspifdefs.h"
 #include "lispemul.h"
 #include "devif.h"
 #include "iopage.h"
@@ -68,8 +69,6 @@ extern DLword *DisplayRegion68k_end_addr;
 extern DspInterface currentdsp;
 extern void docopy(int newx, int newy);
 
-extern PFUL GenericReturnT(void);
-extern void GenericPanic(void);
 extern unsigned long VGA_not_color(DspInterface dsp);
 extern void VGA_exit(DspInterface dsp);
 extern unsigned long Dosbbt1(DspInterface dsp,  DLword *buf, DLword left, DLword top, DLword swidth, DLword height);
@@ -78,8 +77,8 @@ extern unsigned long Dosbbt3(DspInterface dsp,  DLword *buf, DLword left, DLword
 extern void Dosclearbanks(DspInterface dsp);
 extern long DOSCursorVisible(DspInterface dsp, IOPAGE *iop);
 extern long dos_cursor_invisible(DspInterface dsp, IOPAGE *iop);
-extern int dostaking_mouse_down(DspInterface dsp, IOPAGE *iop);
-extern int dostaking_mouse_up(int newx, int newy);
+extern unsigned long dostaking_mouse_down(DspInterface dsp, IOPAGE *iop);
+extern unsigned long dostaking_mouse_up(int newx, int newy);
 
 void VESA_Intrpt_Hndlr(void);
 void *VESA_prev_hndlr; /* addr of previous 0x10 intercept      */

src/vgainit.c

@@ -18,8 +18,8 @@
 
 extern unsigned long Dosbbt1(DspInterface dsp,  DLword *buf, DLword left, DLword top, DLword swidth, DLword height);
 extern unsigned long Dosbbt2(DspInterface dsp,  DLword *buf, DLword left, DLword top, DLword swidth, DLword height);
-extern int dostaking_mouse_down(DspInterface dsp, IOPAGE *iop);
-extern int dostaking_mouse_up(int newx, int newy);
+extern unsigned long dostaking_mouse_down(DspInterface dsp, IOPAGE *iop);
+extern unsigned long dostaking_mouse_up(int newx, int newy);
 
 extern DLword *DisplayRegion68k;
 extern DLword *DisplayRegion68k_end_addr;
@@ -139,8 +139,8 @@ VGA_init(DspInterface dsp, char *lispbitmap, int width_hint, int height_hint, in
   dsp->BytesPerLine = 80;
   dsp->LinesPerBank = 512;
 
-  dsp->mouse_invisible = (PFV)&dostaking_mouse_down;
-  dsp->mouse_visible = (PFV)&dostaking_mouse_up;
+  dsp->mouse_invisible = &dostaking_mouse_down;
+  dsp->mouse_visible = &dostaking_mouse_up;
 
   dsp->device.locked = FALSE;
   dsp->device.active = FALSE;

src/xinit.c

@@ -275,18 +275,20 @@ DspInterface X_init(DspInterface dsp, LispPTR lispbitmap, unsigned width_hint, u
   /************************************************************/
   dsp->Display.width = ((dsp->Display.width + 31) >> 5) << 5;
 
-  dsp->device.enter = (PFV)Open_Display;
-  dsp->device.exit = (PFV)lisp_Xexit;
+  /*
+   * Device methods
+   */
+  dsp->device.enter = (void (*)(void *))Open_Display;
+  dsp->device.exit = (void (*)(void *))lisp_Xexit;
+  dsp->device.before_raid = (void (*)(void *))Xevent_before_raid;
+  dsp->device.after_raid = (void (*)(void *))Xevent_after_raid;
 
-  dsp->bitblt_to_screen = (PFUL)clipping_Xbitblt;
-
-  dsp->device.before_raid = (PFV)Xevent_before_raid;
-  dsp->device.after_raid = (PFV)Xevent_after_raid;
+  dsp->bitblt_to_screen = clipping_Xbitblt;
 
   dsp->BitGravity = NorthWestGravity;
 
-  dsp->cleardisplay = (PFV)GenericReturnT;
-  dsp->set_color_map_entry = (PFUL)GenericReturnT;
+  dsp->cleardisplay = (unsigned long (*)(DspInterface))GenericReturnT;
+  dsp->set_color_map_entry = GenericReturnT;
 
   /* Set the geometry of the Visible (Lisp) window. */
   dsp->Visible.width =