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CLK/Machines/Apple/AppleII/Joystick.hpp
2021-02-16 19:39:22 -05:00

113 lines
3.3 KiB
C++

//
// Joystick.hpp
// Clock Signal
//
// Created by Thomas Harte on 16/02/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#ifndef AppleII_Joystick_hpp
#define AppleII_Joystick_hpp
#include "../../../Inputs/Joystick.hpp"
#include <memory>
#include <vector>
namespace Apple {
namespace II {
class JoystickPair {
public:
JoystickPair() {
// Add a couple of joysticks.
joysticks_.emplace_back(new Joystick);
joysticks_.emplace_back(new Joystick);
}
class Joystick: public Inputs::ConcreteJoystick {
public:
Joystick() :
ConcreteJoystick({
Input(Input::Horizontal),
Input(Input::Vertical),
// The Apple II offers three buttons between two joysticks;
// this emulator puts three buttons on each joystick and
// combines them.
Input(Input::Fire, 0),
Input(Input::Fire, 1),
Input(Input::Fire, 2),
}) {}
void did_set_input(const Input &input, float value) final {
if(!input.info.control.index && (input.type == Input::Type::Horizontal || input.type == Input::Type::Vertical))
axes[(input.type == Input::Type::Horizontal) ? 0 : 1] = 1.0f - value;
}
void did_set_input(const Input &input, bool value) final {
if(input.type == Input::Type::Fire && input.info.control.index < 3) {
buttons[input.info.control.index] = value;
}
}
bool buttons[3] = {false, false, false};
float axes[2] = {0.5f, 0.5f};
};
inline bool button(size_t index) {
return joystick(0)->buttons[index] || joystick(1)->buttons[2-index];
}
inline bool analogue_channel_is_discharged(size_t channel) {
return (1.0f - static_cast<Joystick *>(joysticks_[channel >> 1].get())->axes[channel & 1]) < analogue_charge_ + analogue_biases_[channel];
}
inline void update_charge(float one_mhz_cycles = 1.0f) {
analogue_charge_ = std::min(analogue_charge_ + one_mhz_cycles * (1.0f / 2820.0f), 1.1f);
}
inline void access_c070() {
// Permit analogue inputs that are currently discharged to begin a charge cycle.
// Ensure those that were still charging retain that state.
for(size_t c = 0; c < 4; ++c) {
if(analogue_channel_is_discharged(c)) {
analogue_biases_[c] = 0.0f;
} else {
analogue_biases_[c] += analogue_charge_;
}
}
analogue_charge_ = 0.0f;
}
const std::vector<std::unique_ptr<Inputs::Joystick>> &get_joysticks() {
return joysticks_;
}
private:
// On an Apple II, the programmer strobes 0xc070 and that causes each analogue input
// to begin a charge and discharge cycle **if they are not already charging**.
// The greater the analogue input, the faster they will charge and therefore the sooner
// they will discharge.
//
// This emulator models that with analogue_charge_ being essentially the amount of time,
// in charge threshold units, since 0xc070 was last strobed. But if any of the analogue
// inputs were already partially charged then they gain a bias in analogue_biases_.
//
// It's a little indirect, but it means only having to increment the one value in the
// main loop.
float analogue_charge_ = 0.0f;
float analogue_biases_[4] = {0.0f, 0.0f, 0.0f, 0.0f};
std::vector<std::unique_ptr<Inputs::Joystick>> joysticks_;
inline Joystick *joystick(size_t index) {
return static_cast<Joystick *>(joysticks_[index].get());
}
};
}
}
#endif /* AppleII_Joystick_hpp */