[input] Add logical axes

Like logical buttons, logical axes are engine-defined destinations to
which input ("physical") axes can be bound.

include/QF/input.h

@@ -80,7 +80,41 @@ typedef struct in_device_s {
 	const char *id;
 } in_device_t;
 
-/*** Current state of the button.
+/*** Recipe for converting an axis to a floating point value.
+
+	Recipes apply only to absolute axes.
+
+	\a deadzone applies only to balanced axes, thus it doubles as a flag
+	for balanced (>= 0) or unbalanced (< 0).
+
+	\a curve is applied after the input has been converted
+*/
+typedef struct in_recipe_s {
+	int         minzone;	///< Size of deadzone near axis minimum
+	int         maxzone;	///< Size of deadzone near axis maximum
+	int         deadzone;	///< Size of deadzone near axis center (balanced)
+	float       curve;		///< Power factor for absolute axes
+} in_recipe_t;
+
+typedef enum {
+	ina_set,		///< write the axis value to the destination
+	ina_accumulate,	///< add the axis value to the destination
+} in_axis_mode;
+
+/*** Logical axis.
+
+	Logical axes are the inputs defined by the game on which axis inputs
+	(usually "physical" axes) can act. Depending on the mode, the physical
+	axis value is either written as-is, or added to the existing value. It is
+	the responsibility of the code using the axis to clear the value for
+	accumulated inputs.
+*/
+typedef struct in_axis_s {
+	float       value;		///< converted value of the axis
+	in_axis_mode mode;		///< method used for updating the destination
+} in_axis_t;
+
+/*** Current state of the logical button.
 
 	Captures the current state and any transitions during the last frame.
 	Not all combinations are valid (inb_edge_up|inb_down and inb_edge_down
@@ -94,6 +128,14 @@ typedef enum {
 	inb_edge_up   = 1<<2,	///< button released this frame
 } in_button_state;
 
+/*** Logical button.
+
+	Logical buttons are the inputs defined by the game on which button inputs
+	(usually "physical" buttons) can act. Up to two button inputs can be
+	bound to a logical button. The logical button acts as an or gate where
+	either input will put the logical button in the pressed state, and both
+	inputs must be inactive for the logical button to be released.
+*/
 typedef struct in_button_s {
 	int     down[2];        ///< button ids holding this button down
 	int     state;          ///< in_button_state
@@ -222,6 +264,8 @@ void IN_ClearStates (void);
 
 int IN_RegisterButton (in_button_t *button, const char *name,
 					   const char *description);
+int IN_RegisterAxis (in_axis_t *axis, const char *name,
+					 const char *description);
 
 void IN_Move (void); // FIXME: was cmduser_t?
 // add additional movement on top of the keyboard move cmd

libs/input/Makemodule.am

@@ -20,6 +20,7 @@ libs_input_libQFinput_la_DEPENDENCIES=	$(input_deps)
 libs_input_libQFinput_la_SOURCES= \
 	libs/input/keys.c \
 	libs/input/old_keys.c \
+	libs/input/in_axis.c \
 	libs/input/in_button.c \
 	libs/input/in_common.c \
 	libs/input/in_event.c

libs/input/in_axis.c

@@ -0,0 +1,85 @@
+/*
+	in_axis.c
+
+	Logical axis support
+
+	Copyright (C) 2021 Bill Currie <bill@taniwha.org>
+
+	Author: Bill Currie <bill@taniwha.org>
+	Date: 2021/10/1
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif
+
+#include "QF/cmd.h"
+#include "QF/hash.h"
+#include "QF/input.h"
+#include "QF/sys.h"
+
+typedef struct regaxis_s {
+	const char *name;
+	const char *description;
+	in_axis_t  *axis;
+} regaxis_t;
+
+static hashtab_t *axis_tab;
+
+static const char *
+axis_get_key (const void *b, void *data)
+{
+	__auto_type regaxis = (const regaxis_t *) b;
+	return regaxis->name;
+}
+
+static void
+axis_free (void *b, void *data)
+{
+	free (b);
+}
+
+VISIBLE int
+IN_RegisterAxis (in_axis_t *axis, const char *name, const char *description)
+{
+	if (Hash_Find (axis_tab, name)) {
+		return 0;
+	}
+	regaxis_t *regaxis = malloc (sizeof (regaxis_t));
+	regaxis->name = name;
+	regaxis->description = description;
+	regaxis->axis = axis;
+
+	return 1;
+}
+
+static void __attribute__((constructor))
+in_axis_init (void)
+{
+	axis_tab = Hash_NewTable (127, axis_get_key, axis_free, 0, 0);
+}