Init

2026-05-29 01:11:50 +02:00
parent f4e6d925ab
commit 8cb43eb815
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+// This file is part of Necroware's GamePort adapter firmware.
+// Copyright (C) 2021 Necroware
+//
+// 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 3 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, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <Arduino.h>
+
+/// Class to read analog axis.
+///
+/// Usually PC joystick axes are specified to have 100 Ohm resistance, but
+/// many analog joysticks have old, bad, or just wrong resistors. This ends
+/// up in incorrect positions and is especially bad for games, which don't
+/// have calibration features. This class takes care of this issue and
+/// applies automatic calibration on every read.
+template <int ID>
+class AnalogAxis {
+public:
+  /// Constructor.
+  ///
+  /// The initial state of the joystick is considered as middle
+  /// which is used for autocalibration.
+  AnalogAxis() {
+    pinMode(ID, INPUT);
+    m_mid = analogRead(ID);
+    m_min = m_mid - 100;
+    m_max = m_mid + 100;
+  }
+
+  /// Gets the axis state.
+  ///
+  /// This function automatically recalculates the outer limits and
+  /// readjusts the position of the joystick.
+  /// @returns a value between 0 and 1023
+  uint16_t get() {
+    const auto value = analogRead(ID);
+    if (value < m_min) {
+      m_min = value;
+    } else if (value > m_max) {
+      m_max = value;
+    }
+
+    if (value < m_mid) {
+      return map(value, m_min, m_mid, 1023, 512);
+    }
+    return map(value, m_mid, m_max, 511, 0);
+  }
+
+private:
+  int m_mid;
+  int m_min;
+  int m_max;
+};