Init

2026-05-29 01:11:50 +02:00
parent f4e6d925ab
commit 8cb43eb815
40 changed files with 17776 additions and 0 deletions
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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 "DigitalPin.h"
+#include "Joystick.h"
+
+/// Class to communicate with Gravis joysticks using GrIP.
+/// @remark This is a green field implementation, but it was heavily
+///         inspired by Linux Gravis/Kensington GrIP driver
+///         implementation. See
+class GrIP : public Joystick {
+  ///         https://github.com/torvalds/linux/blob/master/drivers/input/joystick/grip.c
+public:
+  /// Resets the joystick and tries to detect the model.
+  bool init() override {
+    while (!readPacket())
+      ;
+    return true;
+  }
+
+  /// Reads the joystick state.
+  /// @returns the state of axis, buttons etc.
+  /// @remark if reading the state fails, the last known state is
+  ///         returned and the joystick reset is executed.
+  bool update() override {
+
+    const auto packet = readPacket();
+    if (packet == 0) {
+      return false;
+    }
+
+    const auto getBit = [&](uint8_t pos) { return uint8_t(packet >> pos) & 1; };
+
+    m_state.axes[0] = map(1 + getBit(15) - getBit(16), 0, 2, 0, 1023);
+    m_state.axes[1] = map(1 + getBit(13) - getBit(12), 0, 2, 0, 1023);
+
+    m_state.buttons = getBit(8);
+    m_state.buttons |= getBit(3) << 1;
+    m_state.buttons |= getBit(7) << 2;
+    m_state.buttons |= getBit(6) << 3;
+    m_state.buttons |= getBit(10) << 4;
+    m_state.buttons |= getBit(11) << 5;
+    m_state.buttons |= getBit(5) << 6;
+    m_state.buttons |= getBit(2) << 7;
+    m_state.buttons |= getBit(0) << 8;
+    m_state.buttons |= getBit(1) << 9;
+
+    return true;
+  }
+
+  const State &getState() const override {
+    return m_state;
+  }
+
+  const Description &getDescription() const override {
+    static Description desc{"Gravis GamePad Pro", 2, 10, 0};
+    return desc;
+  }
+
+private:
+  /// Supported Gravis model types.
+  ///
+  /// @remark currently only GamePad Pro is supported and
+  //          this enum is not used yet
+  enum class Model {
+
+    /// Unknown model
+    GRIP_UNKNOWN,
+
+    /// GamePad Pro
+    GRIP_GAMEPAD_PRO,
+  };
+
+  DigitalInput<GamePort<2>::pin, true> m_clock;
+  DigitalInput<GamePort<7>::pin, true> m_data;
+  State m_state;
+
+  /// Read bits packet from the joystick.
+  uint32_t readPacket() const {
+
+    // Gravis GamePad Pro sends 24 bits long packages of data all the
+    // time. Every package starts with a binary tag sequence 011111.
+
+    static const auto length = 24u;
+    uint32_t result = 0u;
+
+    // read a package of 24 bits
+    for (auto i = 0u; i < length; i++) {
+      if (!m_clock.wait(Edge::falling, 100)) {
+        return 0u;
+      }
+      result |= uint32_t(m_data.isHigh()) << i;
+    }
+
+    // alighn the bits to have the binary tag in front. This code
+    // was taken almost unchanged from the linux kernel.
+    for (auto i = 0u; i < length; i++) {
+      result = (result >> 1) | (result & 1) << (length - 1u);
+      if ((result & 0xfe4210) == 0x7c0000) {
+        return result;
+      }
+    }
+    return 0u;
+  }
+};