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CLK/Machines/Amiga/MouseJoystick.cpp
2021-11-26 18:08:39 -05:00

125 lines
2.9 KiB
C++

//
// MouseJoystick.cpp
// Clock Signal
//
// Created by Thomas Harte on 26/11/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#include "MouseJoystick.hpp"
#include <algorithm>
using namespace Amiga;
// MARK: - Mouse.
int Mouse::get_number_of_buttons() {
return 2;
}
void Mouse::set_button_pressed(int button, bool is_set) {
switch(button) {
case 0:
cia_state_ = (cia_state_ &~ 0x40) | (is_set ? 0 : 0x40);
break;
default:
break;
}
}
uint8_t Mouse::get_cia_button() const {
return cia_state_;
}
void Mouse::reset_all_buttons() {
cia_state_ = 0xff;
}
void Mouse::move(int x, int y) {
position_[0] += x;
position_[1] += y;
}
uint16_t Mouse::get_position() {
// The Amiga hardware retains only eight bits of position
// for the mouse; its software polls frequently and maps
// changes into a larger space.
//
// On modern computers with 5k+ displays and trackpads, it
// proved empirically possible to overflow the hardware
// counters more quickly than software would poll.
//
// Therefore the approach taken for mapping mouse motion
// into the Amiga is to do it in steps of no greater than
// [-128, +127], as per the below.
const int pending[] = {
position_[0], position_[1]
};
const int8_t change[] = {
int8_t(std::clamp(pending[0], -128, 127)),
int8_t(std::clamp(pending[1], -128, 127))
};
position_[0] -= change[0];
position_[1] -= change[1];
declared_position_[0] += change[0];
declared_position_[1] += change[1];
return uint16_t(
(declared_position_[1] << 8) |
declared_position_[0]
);
}
// MARK: - Joystick.
// TODO: add second fire button.
Joystick::Joystick() :
ConcreteJoystick({
Input(Input::Up),
Input(Input::Down),
Input(Input::Left),
Input(Input::Right),
Input(Input::Fire, 0),
}) {}
void Joystick::did_set_input(const Input &input, bool is_active) {
// Accumulate state.
inputs_[input.type] = is_active;
// Determine what that does to the two position bits.
const auto low =
(inputs_[Input::Type::Down] ^ inputs_[Input::Type::Right]) |
(inputs_[Input::Type::Right] << 1);
const auto high =
(inputs_[Input::Type::Up] ^ inputs_[Input::Type::Left]) |
(inputs_[Input::Type::Left] << 1);
// Ripple upwards if that affects the mouse position counters.
const uint8_t previous_low = position_ & 3;
uint8_t low_upper = (position_ >> 2) & 0x3f;
const uint8_t previous_high = (position_ >> 8) & 3;
uint8_t high_upper = (position_ >> 10) & 0x3f;
if(!low && previous_low == 3) ++low_upper;
if(!previous_low && low == 3) --low_upper;
if(!high && previous_high == 3) ++high_upper;
if(!previous_high && high == 3) --high_upper;
position_ = uint16_t(
low | ((low_upper & 0x3f) << 2) |
(high << 8) | ((high_upper & 0x3f) << 10)
);
}
uint16_t Joystick::get_position() {
return position_;
}
uint8_t Joystick::get_cia_button() const {
return inputs_[Input::Type::Fire] ? 0xbf : 0xff;
}