Add touch input support, add fast scrolling support for coverflow display mode, fix use after free bug in banner list mode

arm7/source/touchScreen.cpp

@@ -0,0 +1,146 @@
+#include "common.h"
+#include <nds/input.h>
+#include <nds/arm7/touch.h>
+
+// See: https://github.com/blocksds/libnds/blob/master/source/arm7/input.c
+
+// === Touchscreen filter configuration ===
+
+// Replace Z1/Z2 values with X/Y noisiness measurements.
+// #define TOUCH_DEBUG_NOISINESS
+
+// The number of frames to debounce/hold pen presses for.
+// Set to 0 to disable.
+#define PEN_DOWN_DEBOUNCE 1
+// The shift (1 << N) used for the IIR filter to average noisy samples across
+// time. Set to 0 to disable.
+#define TOUCH_MAX_NOISE_PEN_UP_IIR_SHIFT 5
+
+// The maximum value of noisiness for pressing a pen down (measurement now valid).
+#define TOUCH_MAX_NOISE_PEN_DOWN 38
+// The minimum value of noisiness for lifting a pen up (measurement no longer valid).
+#define TOUCH_MAX_NOISE_PEN_UP   50
+
+// === Touchscreen filter ===
+
+// IIR filter constants.
+#define TOUCH_MAX_NOISE_PEN_UP_IIR_RATIO (1 << TOUCH_MAX_NOISE_PEN_UP_IIR_SHIFT)
+#define TOUCH_MAX_NOISE_PEN_UP_IIR_MIN (TOUCH_MAX_NOISE_PEN_UP - TOUCH_MAX_NOISE_PEN_UP_IIR_RATIO)
+
+typedef struct {
+    u16 value;      // 1..4095, 0 if invalid
+    u16 noisiness;  // 0..4095, ~15-16 = 1 pixel
+} libnds_touchMeasurementFilterResult;
+
+/**
+ * @brief Perform filtering on the raw touch samples provided to return one
+ * averaged sample and an estimate of how noisy it is, while skipping outliers.
+ *
+ * Internal. See touchFilter.c for more information.
+ */
+extern "C" libnds_touchMeasurementFilterResult libnds_touchMeasurementFilter(u16 values[5]);
+
+void touch_init()
+{
+    touchInit();
+}
+
+bool touch_update(touchPosition& touchPos)
+{
+#if PEN_DOWN_DEBOUNCE > 0
+    static touchPosition lastTouchPosition;
+    static bool lastPenDown = false;
+    static u8 penDownDebounce = 0;
+#else
+    touchPosition lastTouchPosition;
+    bool lastPenDown = false;
+#endif
+
+    bool penDown = touchPenDown();
+    if (penDown)
+    {
+        // Set penDown to false for later fallthroughs to noPenDown.
+        // It will be set to true if all the touch filtering ensures the readout is valid.
+        penDown = false;
+
+        // Measure new touch position.
+        touchRawArray data;
+        if (!touchReadData(&data))
+            goto noPenDown;
+
+        libnds_touchMeasurementFilterResult rawXresult = libnds_touchMeasurementFilter(data.rawX);
+        if (!rawXresult.value)
+            goto noPenDown;
+        libnds_touchMeasurementFilterResult rawYresult = libnds_touchMeasurementFilter(data.rawY);
+        if (!rawYresult.value)
+            goto noPenDown;
+
+        // Valid sample read.
+        u16 noisiness = rawXresult.noisiness > rawYresult.noisiness ? rawXresult.noisiness : rawYresult.noisiness;
+        if (noisiness <= (lastPenDown ? TOUCH_MAX_NOISE_PEN_UP : TOUCH_MAX_NOISE_PEN_DOWN))
+        {
+            lastTouchPosition.z1 = libnds_touchMeasurementFilter(data.z1).value;
+            lastTouchPosition.z2 = libnds_touchMeasurementFilter(data.z2).value;
+
+#if TOUCH_MAX_NOISE_PEN_UP_IIR_SHIFT > 0
+            // Apply an IIR filter on noisy X/Y samples.
+            // Skip the IIR filter if the pen was just pressed.
+            int n = (noisiness - TOUCH_MAX_NOISE_PEN_UP_IIR_MIN);
+            if (noisiness <= 0 || !lastPenDown)
+            {
+                lastTouchPosition.rawx = rawXresult.value;
+                lastTouchPosition.rawy = rawYresult.value;
+            }
+            else if (noisiness <= TOUCH_MAX_NOISE_PEN_UP_IIR_RATIO)
+            {
+                lastTouchPosition.rawx =
+                    ((rawXresult.value * (TOUCH_MAX_NOISE_PEN_UP_IIR_RATIO - n))
+                     + (lastTouchPosition.rawx * n)) >> TOUCH_MAX_NOISE_PEN_UP_IIR_SHIFT;
+                lastTouchPosition.rawy =
+                    ((rawYresult.value * (TOUCH_MAX_NOISE_PEN_UP_IIR_RATIO - n))
+                     + (lastTouchPosition.rawy * n)) >> TOUCH_MAX_NOISE_PEN_UP_IIR_SHIFT;
+            }
+#else
+            lastTouchPosition.rawx = rawXresult.value;
+            lastTouchPosition.rawy = rawYresult.value;
+#endif
+
+            touchApplyCalibration(lastTouchPosition.rawx, lastTouchPosition.rawy, &lastTouchPosition.px, &lastTouchPosition.py);
+            penDown = true;
+        }
+
+#ifdef TOUCH_DEBUG_NOISINESS
+        lastTouchPosition.z1 = rawXresult.noisiness;
+        lastTouchPosition.z2 = rawYresult.noisiness;
+#endif
+    }
+
+noPenDown:
+#if PEN_DOWN_DEBOUNCE > 0
+    // Perform simple debouncing.
+    // Hold new presses for PEN_DOWN_DEBOUNCE frames.
+    if (!penDownDebounce)
+    {
+        if (lastPenDown != penDown)
+        {
+            lastPenDown = penDown;
+            if (penDown)
+                penDownDebounce = PEN_DOWN_DEBOUNCE;
+        }
+    }
+    else
+    {
+        penDownDebounce--;
+    }
+#else
+    lastPenDown = penDown;
+#endif
+
+    // Return the touch position and pen down.
+    if (lastPenDown)
+    {
+        touchPos = lastTouchPosition;
+    }
+
+    return lastPenDown;
+}