mirror of https://github.com/lefticus/6502-cpp.git
433 lines
12 KiB
C++
433 lines
12 KiB
C++
#include <cstdint>
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#include <array>
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#include <utility>
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#include <algorithm>
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#include <tuple>
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namespace {
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volatile uint8_t &memory(const uint16_t loc)
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{
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return *reinterpret_cast<uint8_t *>(loc);
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}
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template<typename T>
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auto square(T t) {
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return t * t;
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}
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constexpr bool test_bit(const uint8_t data, const uint8_t bit)
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{
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return (data & (1 << bit)) != 0;
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};
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struct Color
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{
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uint8_t num;
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uint8_t r;
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uint8_t g;
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uint8_t b;
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};
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struct JoyStick
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{
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static constexpr uint16_t JOYSTICK_PORT_A = 56320; // joystick #2
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static constexpr uint16_t JOYSTICK_PORT_B = 56321; // joystick #1
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struct PortData
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{
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uint8_t data;
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};
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JoyStick(const PortData d)
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: up(!test_bit(d.data, 0)),
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down(!test_bit(d.data, 1)),
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left(!test_bit(d.data, 2)),
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right(!test_bit(d.data, 3)),
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fire(!test_bit(d.data, 4))
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{
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}
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JoyStick(const uint8_t port_num)
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: JoyStick(PortData{port_num==2?memory(JOYSTICK_PORT_A):memory(JOYSTICK_PORT_B)})
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{
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}
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auto direction_vector() const
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{
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return std::make_pair(left?-1:(right?1:0), up?-1:(down?1:0));
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}
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bool up,down,left,right,fire;
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};
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///
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/// New Code
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///
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template<typename L1, typename L2, typename R1, typename R2>
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auto operator+=(std::pair<L1&, L2&> lhs, const std::pair<R1, R2> &rhs)
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{
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lhs.first += rhs.first;
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lhs.second += rhs.second;
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return lhs;
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}
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template<typename L1, typename L2, typename R1, typename R2>
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decltype(auto) operator*=(std::pair<L1, L2> &lhs, const std::pair<R1, R2> &rhs)
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{
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lhs.first *= rhs.first;
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lhs.second *= rhs.second;
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return (lhs);
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}
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void set_bit(const uint16_t loc, const uint8_t bitnum, bool val)
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{
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if (val) {
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memory(loc) |= (1 << bitnum);
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} else {
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memory(loc) &= (0xFF ^ (1 << bitnum));
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}
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}
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struct Player
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{
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Player(const uint8_t num, std::pair<volatile uint8_t &, volatile uint8_t &> sprite_pos,
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const std::pair<uint8_t, uint8_t> &start_pos)
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: player_num(num),
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pos(sprite_pos)
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{
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pos = start_pos;
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}
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void update_position()
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{
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pos.second += JoyStick(player_num).direction_vector().second * 3;
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};
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void scored() {
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++score;
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}
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const uint8_t player_num;
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std::pair<volatile uint8_t &, volatile uint8_t &> pos;
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uint8_t score = '0';
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};
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///
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/// End New Code
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///
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struct VIC_II
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{
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static constexpr uint8_t SPRITE_ALIGNMENT = 64;
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static constexpr uint16_t SPRITE_DATA_POINTERS = 2040;
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static constexpr uint16_t VIDEO_REGISTERS = 53248;
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static constexpr uint16_t VIDEO_MEMORY = 1024;
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static constexpr uint16_t BORDER_COLOR = 53280;
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static constexpr uint16_t BACKGROUND_COLOR = 53281;
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static constexpr uint16_t SPRITE_POSITION_REGISTERS = VIDEO_REGISTERS;
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static constexpr uint16_t SPRITE_ENABLE_BITS = VIDEO_REGISTERS + 21;
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static constexpr uint16_t SPRITE_EXPAND_VERTICAL = VIDEO_REGISTERS + 23;
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static constexpr uint16_t SPRITE_PRIORITY = VIDEO_REGISTERS + 27;
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static constexpr uint16_t SPRITE_MULTICOLOR = VIDEO_REGISTERS + 28;
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static constexpr uint16_t SPRITE_EXPAND_HORIZONTAL = VIDEO_REGISTERS + 29;
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static constexpr uint16_t SPRITE_COLLISIONS = VIDEO_REGISTERS + 30;
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static constexpr uint16_t SPRITE_0_COLOR = VIDEO_REGISTERS + 39;
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static constexpr uint16_t SPRITE_1_COLOR = SPRITE_0_COLOR + 1;
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static constexpr uint16_t SPRITE_2_COLOR = SPRITE_1_COLOR + 1;
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static constexpr uint16_t SCREEN_RASTER_LINE = 53266;
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volatile uint8_t& border() {
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return memory(BORDER_COLOR);
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}
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volatile uint8_t& background() {
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return memory(BACKGROUND_COLOR);
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}
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volatile uint8_t& display(uint8_t x, uint8_t y)
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{
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return memory(VIDEO_MEMORY + y * 40 + x);
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}
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template<uint8_t r, uint8_t g, uint8_t b>
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static auto color_comparison(const Color &lhs, const Color &rhs)
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{
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// distance between colors:
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// sqrt( (r1 - r2)^2 + (g1 - g2)^2 + (b1 - b2)^2 )
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return (square(lhs.r - r) + square(lhs.g - g) + square(lhs.b - b))
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< (square(rhs.r - r) + square(rhs.g - g) + square(rhs.b - b));
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}
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template<uint8_t r, uint8_t g, uint8_t b, typename Colors>
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static auto nearest_color(const Colors &colors)
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{
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return *std::min_element(std::begin(colors), std::end(colors),
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color_comparison<r,g,b>);
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}
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auto frame(Player &p1, Player &p2)
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{
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struct Frame
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{
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Frame(VIC_II &t_vic, Player &p1, Player &p2)
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: player1(p1), player2(p2), vic(t_vic)
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{
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while (memory(SCREEN_RASTER_LINE) != 250) {}
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}
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~Frame() {
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vic.display(10, 12) = player1.score;
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vic.display(20, 12) = player2.score;
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}
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Player &player1;
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Player &player2;
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VIC_II &vic;
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};
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return Frame(*this, p1, p2);
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}
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template<bool multicolor>
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struct SpriteLine {
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uint8_t pixels[3];
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typedef uint_least64_t numeric_t;
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/// Pixel format converter.
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static constexpr uint8_t c(const numeric_t m)
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{
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if constexpr (multicolor)
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// 0b00ii00jj00kk00ll -> 0biijjkkll
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return uint8_t(m >> 0 & 3 << 0) |
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uint8_t(m >> 2 & 3 << 2) |
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uint8_t(m >> 4 & 3 << 4) |
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uint8_t(m >> 6 & 3 << 6);
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return uint8_t(m);
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}
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/// Input bits per byte.
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constexpr static auto ibb = multicolor ? 16 : 8;
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/// Constructor.
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constexpr SpriteLine(const numeric_t line)
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: pixels{c(line >> (2 * ibb)), c(line >> ibb), c(line)}
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{}
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};
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template<bool multicolor>
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struct Sprite {
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typedef SpriteLine<multicolor> Line;
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alignas(SPRITE_ALIGNMENT) Line lines[SPRITE_ALIGNMENT / sizeof(Line)];
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};
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typedef Sprite<false> HighResSprite;
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typedef Sprite<true> MultiColorSprite;
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///
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/// New Code
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///
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template<bool multicolor>
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void enable_sprite(const uint8_t sprite_number,
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const Sprite<multicolor>& bitmap,
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const bool low_priority,
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const bool double_width, const bool double_height)
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{
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#if 0 // error: static_assert expression is not an integral constant
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static_assert((std::ptrdiff_t(bitmap.memory) & 0x7000) != 0x1000,
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"The addresses 0x1000 to 0x1fff and 0x9000 to 0x9fff"
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"point to the character generator ROM, not RAM.");
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static_assert(std::ptrdiff_t(bitmap.memory) < 0x4000,
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"The data must be within the first (default)"
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" 16KiB VIC-II bank.");
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#endif
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memory(SPRITE_DATA_POINTERS + sprite_number)
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= (std::ptrdiff_t(bitmap.lines) & 0x3fff) / SPRITE_ALIGNMENT;
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set_bit(SPRITE_ENABLE_BITS, sprite_number, true);
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set_bit(SPRITE_EXPAND_HORIZONTAL, sprite_number, double_width);
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set_bit(SPRITE_EXPAND_VERTICAL, sprite_number, double_height);
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set_bit(SPRITE_MULTICOLOR, sprite_number, multicolor);
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set_bit(SPRITE_PRIORITY, sprite_number, low_priority);
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}
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auto sprite_collisions() {
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const auto collisions = memory(SPRITE_COLLISIONS);
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return std::make_tuple(
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test_bit(collisions, 0),test_bit(collisions, 1),test_bit(collisions, 2),
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test_bit(collisions, 3),test_bit(collisions, 4),test_bit(collisions, 5),
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test_bit(collisions, 6),test_bit(collisions, 7));
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}
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volatile uint8_t &sprite_1_color()
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{
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return memory(SPRITE_1_COLOR);
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}
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volatile uint8_t &sprite_2_color()
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{
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return memory(SPRITE_2_COLOR);
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}
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std::pair<volatile uint8_t &, volatile uint8_t &>
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sprite_pos(const uint8_t sprite_num)
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{
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return {
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memory(SPRITE_POSITION_REGISTERS + sprite_num * 2),
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memory(SPRITE_POSITION_REGISTERS + sprite_num * 2 + 1)
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};
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}
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///
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/// End New Code
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///
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};
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}
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int main()
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{
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const std::array<Color, 16> colors = {{
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Color{0, 0x00, 0x00, 0x00},
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Color{1, 0xFF, 0xFF, 0xFF},
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Color{2, 0x88, 0x39, 0x32},
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Color{3, 0x67, 0xB6, 0xBD},
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Color{4, 0x8B, 0x3F, 0x96},
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Color{5, 0x55, 0xA0, 0x49},
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Color{6, 0x40, 0x31, 0x8D},
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Color{7, 0xBF, 0xCE, 0x72},
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Color{8, 0x8B, 0x54, 0x29},
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Color{9, 0x57, 0x42, 0x00},
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Color{10, 0xB8, 0x69, 0x62},
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Color{11, 0x50, 0x50, 0x50},
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Color{12, 0x78, 0x78, 0x78},
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Color{13, 0x94, 0xE0, 0x89},
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Color{14, 0x78, 0x69, 0xC4},
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Color{15, 0x9F, 0x9F, 0x9F}
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}};
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VIC_II vic;
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/// The ball image.
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static const VIC_II::HighResSprite sBall
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{{
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0b000000000000000000000000,
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0b000000000000000000000000,
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0b000000000111111000000000,
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0b000000011111111110000000,
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0b000000110111111111000000,
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0b000001100011111111100000,
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0b000001110111111111100000,
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0b000011111111111111110000,
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0b000011111111111111110000,
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0b000011111111111111110000,
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0b000000111111111111000000,
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0b000011000000000000110000,
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0b000011111111111111110000,
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0b000001111111111111100000,
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0b000001111111111111100000,
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0b000000111111111111000000,
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0b000000011111111110000000,
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0b000000000111111000000000,
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0b000000000000000000000000,
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0b000000000000000000000000,
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0b000000000000000000000000
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}};
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/// The bat image.
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static const VIC_II::MultiColorSprite sBat = {{
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000002200000,
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0x000003300000,
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0x000001100000,
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0x000003300000,
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0x000001100000,
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0x000003300000
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}};
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vic.enable_sprite(0, sBall, true, false, false);
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vic.enable_sprite(1, sBat, false, false, true);
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vic.enable_sprite(2, sBat, false, false, true);
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vic.border() = vic.nearest_color<128,128,128>(colors).num; // 50% grey
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vic.background() = vic.nearest_color<0,0,0>(colors).num; // black
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vic.sprite_1_color() = vic.nearest_color<255,0,0>(colors).num; // red
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vic.sprite_2_color() = vic.nearest_color<0,255,0>(colors).num; // green
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///
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/// Game Logic
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///
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std::pair<int8_t, int8_t> ball_velocity{1,1};
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const auto reset_ball = [&vic]{
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// resets position but keeps velocity
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vic.sprite_pos(0) = std::make_pair(255/2, 255/2);
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};
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reset_ball();
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Player p1(1, vic.sprite_pos(1), {15, 255/2});
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Player p2(2, vic.sprite_pos(2), {255, 255/2});
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///
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/// Game Loop
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///
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while (true) {
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auto frame = vic.frame(p1, p2);
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if (const auto [s0, s1, s2, s3, s4, s5, s6, s7] = vic.sprite_collisions();
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s0 && (s1 || s2))
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{
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// ball hit paddle, invert ball x velocity
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ball_velocity *= std::make_pair(-1, 1);
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// "bounce" ball out of collision area
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vic.sprite_pos(0) += std::make_pair(ball_velocity.first, 0);
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}
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// Update paddle positions
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p1.update_position();
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p2.update_position();
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const auto score = [reset_ball](auto &player){
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// called when a player scores
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player.scored();
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reset_ball();
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};
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if (const auto [ball_x, ball_y] = vic.sprite_pos(0) += ball_velocity;
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ball_y == 45 || ball_y == 235)
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{
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// ball hit the top or bottom wall, invert ball y velocity
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ball_velocity *= std::make_pair(1, -1);
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} else if (ball_x == 1) {
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// ball hit left wall, player 2 scored
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score(p2);
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} else if (ball_x == 255) {
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// ball hit right wall, player 1 scored
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score(p1);
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}
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}
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}
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