@@ -60,6 +60,8 @@ then

 	clang-format -i src/devices/controller.c

 	clang-format -i src/devices/datetime.h

 	clang-format -i src/devices/datetime.c

+	clang-format -i src/devices/debug.h

+	clang-format -i src/devices/debug.c

 	clang-format -i src/uxnasm.c

 	clang-format -i src/uxnemu.c

 	clang-format -i src/uxncli.c

@@ -98,8 +100,8 @@ fi

 echo "Building.."

 ${CC} ${CFLAGS} src/uxnasm.c -o bin/uxnasm

-${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/devices/mouse.c src/devices/controller.c src/devices/screen.c src/devices/audio.c src/uxnemu.c ${UXNEMU_LDFLAGS} -o bin/uxnemu

-${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/uxncli.c -o bin/uxncli

+${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/devices/debug.c src/devices/mouse.c src/devices/controller.c src/devices/screen.c src/devices/audio.c src/uxnemu.c ${UXNEMU_LDFLAGS} -o bin/uxnemu

+${CC} ${CFLAGS} ${CORE} src/devices/system.c src/devices/file.c src/devices/datetime.c src/devices/debug.c src/uxncli.c -o bin/uxncli

 if [ -d "$HOME/bin" ]

 then

@@ -9,6 +9,7 @@ HFILES=\

 	src/devices/audio.h\

 	src/devices/controller.h\

 	src/devices/datetime.h\

+	src/devices/debug.h\

 	src/devices/file.h\

 	src/devices/mouse.h\

 	src/devices/screen.h\

@@ -33,19 +34,19 @@ bin:

 %.rom:Q: %.tal bin/uxnasm

 	bin/uxnasm $stem.tal $target >/dev/null

-bin/uxncli: file.$O datetime.$O system.$O uxncli.$O uxn.$O

+bin/uxncli: file.$O datetime.$O debug.$O system.$O uxncli.$O uxn.$O

 	$LD $LDFLAGS -o $target $prereq

 bin/uxnasm: uxnasm.$O

 	$LD $LDFLAGS -o $target $prereq

-bin/uxnemu: audio.$O controller.$O datetime.$O file.$O mouse.$O screen.$O system.$O uxn.$O uxnemu.$O

+bin/uxnemu: audio.$O controller.$O datetime.$O debug.$O file.$O mouse.$O screen.$O system.$O uxn.$O uxnemu.$O

 	$LD $LDFLAGS -o $target $prereq

 (uxnasm|uxncli|uxnemu|uxn)\.$O:R: src/\1.c

 	$CC $CFLAGS -Isrc -o $target src/$stem1.c

-(audio|controller|datetime|file|mouse|screen|system)\.$O:R: src/devices/\1.c

+(audio|controller|datetime|debug|file|mouse|screen|system)\.$O:R: src/devices/\1.c

 	$CC $CFLAGS -Isrc -o $target src/devices/$stem1.c

 nuke:V: clean

new file mode 100644

@@ -0,0 +1,50 @@

+#include <stdio.h>

+

+#include "../uxn.h"

+#include "debug.h"

+

+/*

+Copyright (c) 2021 Devine Lu Linvega

+Copyright (c) 2021 Andrew Alderwick

+

+Permission to use, copy, modify, and distribute this software for any

+purpose with or without fee is hereby granted, provided that the above

+copyright notice and this permission notice appear in all copies.

+

+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

+WITH REGARD TO THIS SOFTWARE.

+*/

+

+static void

+inspect(Stack *s, char *name)

+{

+	Uint8 x, y;

+	fprintf(stderr, "\n%s\n", name);

+	for(y = 0; y < 0x04; y++) {

+		for(x = 0; x < 0x08; x++) {

+			Uint8 p = y * 0x08 + x;

+			fprintf(stderr,

+				p == s->ptr ? "[%02x]" : " %02x ",

+				s->dat[p]);

+		}

+		fprintf(stderr, "\n");

+	}

+}

+

+/* IO */

+

+Uint8

+debug_dei(Device *d, Uint8 port)

+{

+	DebugDevice *debug = (DebugDevice *)d;

+	return d->dat[port];

+}

+

+void

+debug_deo(Device *d, Uint8 port)

+{

+	(void)d;

+	(void)port;

+	inspect(&d->u->wst, "Working-stack");

+	inspect(&d->u->rst, "Return-stack");

+}

new file mode 100644

@@ -0,0 +1,19 @@

+/*

+Copyright (c) 2021 Devine Lu Linvega

+Copyright (c) 2021 Andrew Alderwick

+

+Permission to use, copy, modify, and distribute this software for any

+purpose with or without fee is hereby granted, provided that the above

+copyright notice and this permission notice appear in all copies.

+

+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

+WITH REGARD TO THIS SOFTWARE.

+*/

+

+typedef struct DebugDevice {

+	Device device;

+	struct UxnScreen *screen;

+} DebugDevice;

+

+Uint8 debug_dei(Device *d, Uint8 port);

+void debug_deo(Device *d, Uint8 port);

\ No newline at end of file

@@ -37,7 +37,7 @@ typedef struct {

 typedef struct Device {

 	struct Uxn *u;

-	Uint8 dat[16], *mem;

+	Uint8 dat[16];

 	Uint8 (*dei)(struct Device *d, Uint8);

 	void (*deo)(struct Device *d, Uint8);

 } Device;

@@ -5,6 +5,7 @@

 #include "devices/system.h"

 #include "devices/file.h"

 #include "devices/datetime.h"

+#include "devices/debug.h"

 /*

 Copyright (c) 2021 Devine Lu Linvega

@@ -15,6 +15,7 @@

 #include "devices/controller.h"

 #include "devices/mouse.h"

 #include "devices/datetime.h"

+#include "devices/debug.h"

 #pragma GCC diagnostic pop

 #pragma clang diagnostic pop

@@ -279,11 +280,9 @@ start(Uxn *u, char *rom)

 	/* unused   */ uxn_port(u, 0xc, nil_dei, nil_deo);

 	/* unused   */ uxn_port(u, 0xd, nil_dei, nil_deo);

 	/* unused   */ uxn_port(u, 0xe, nil_dei, nil_deo);

-	/* unused   */ uxn_port(u, 0xf, nil_dei, nil_deo);

-

+	/* unused   */ uxn_port(u, 0xf, debug_dei, debug_deo);

 	if(!uxn_eval(u, PAGE_PROGRAM))

 		return error("Boot", "Failed to start rom.");

-

 	return 1;

 }