am-kernels/kernels/typing-game/game.c

#include <am.h>
#include <klib.h>
#include <klib-macros.h>

#define MAXCH       256
#define FPS          60
#define CHAR_PER_SEC 10

struct character {
  char ch;
  int x, y, v;
} chars[MAXCH];

int screen_width, screen_height, char_width, char_height;
int hit, miss, wrong;

int randint(int l, int r) {
  return l + (rand() & 0x7fffffff) % (r - l + 1);
}

void new_char() {
  for (int i = 0; i < LENGTH(chars); i++) {
    struct character *c = &chars[i];
    if (c->ch == '\0') {
      c->ch = 'A' + randint(0, 25);
      c->x = randint(0, screen_width - char_width);
      c->y = 0;
      c->v = (screen_height - char_height + 1) / randint(FPS * 3 / 2, FPS * 2);
      return;
    }
  }
}

void progress(int frame) {
  if (frame % (FPS / CHAR_PER_SEC) == 0) {
    new_char();
  }
  for (int i = 0; i < LENGTH(chars); i++) {
    struct character *c = &chars[i];
    if (c->ch) {
      c->y += c->v;
      if (c->y < 0) {
        c->ch = '\0';
      }
      if (c->y + char_height >= screen_height) {
        miss++;
        c->ch = '\0';
      }
    }
  }
}

void check_hit(char ch) {
  int m = -1;
  for (int i = 0; i < LENGTH(chars); i++) {
    struct character *c = &chars[i];
    if (ch == c->ch && c->v > 0 && (m < 0 || c->y > chars[m].y)) {
      m = i;
    }
  }
  if (m == -1) {
    wrong++;
  } else {
    hit++;
    chars[m].v = -(screen_height - char_height + 1) / (FPS);
  }
}

uint32_t px[32 * 16], blank[32 * 16];

void render() {
  static int x[MAXCH], y[MAXCH], n;

  for (int i = 0; i < n; i++) {
    io_write(AM_GPU_FBDRAW, x[i], y[i], blank, char_width, char_height, false);
  }

  n = 0;
  for (int i = 0; i < LENGTH(chars); i++) {
    struct character *c = &chars[i];
    if (c->ch) {
      x[n] = c->x; y[n] = c->y; n++;
      io_write(AM_GPU_FBDRAW, c->x, c->y, px, char_width, char_height, false);
    }
  }
  io_write(AM_GPU_FBDRAW, 0, 0, NULL, 0, 0, true);
  for (int i = 0; i < 80; i++) putch('\b');
  printf("Hit: %d; Miss: %d; Wrong: %d", hit, miss, wrong);
}

char lut[256] = {
  [AM_KEY_A] = 'A', [AM_KEY_B] = 'B', [AM_KEY_C] = 'C', [AM_KEY_D] = 'D',
  [AM_KEY_E] = 'E', [AM_KEY_F] = 'F', [AM_KEY_G] = 'G', [AM_KEY_H] = 'H',
  [AM_KEY_I] = 'I', [AM_KEY_J] = 'J', [AM_KEY_K] = 'K', [AM_KEY_L] = 'L',
  [AM_KEY_M] = 'M', [AM_KEY_N] = 'N', [AM_KEY_O] = 'O', [AM_KEY_P] = 'P',
  [AM_KEY_Q] = 'Q', [AM_KEY_R] = 'R', [AM_KEY_S] = 'S', [AM_KEY_T] = 'T',
  [AM_KEY_U] = 'U', [AM_KEY_V] = 'V', [AM_KEY_W] = 'W', [AM_KEY_X] = 'X',
  [AM_KEY_Y] = 'Y', [AM_KEY_Z] = 'Z',
};

int main() {
  char_width  = 8;
  char_height = 16;

  for (int i = 0; i < char_width * char_height; i ++) px[i] = 0x345678;
  for (int i = 0; i < char_width * char_height; i ++) blank[i] = 0;

  ioe_init();

  screen_width  = io_read(AM_GPU_CONFIG).width;
  screen_height = io_read(AM_GPU_CONFIG).height;

  int current = 0, rendered = 0;
  while (1) {
    int frames = io_read(AM_TIMER_UPTIME).us / (1000000 / FPS);

    while (current < frames) {
      progress(current);
      current++;
    }

    while (1) {
      AM_INPUT_KEYBRD_T ev = io_read(AM_INPUT_KEYBRD);
      if (ev.keycode == AM_KEY_NONE) break;
      if (ev.keydown && lut[ev.keycode]) {
        check_hit(lut[ev.keycode]);
      }
    };

    if (current > rendered) {
      render();
      rendered = current;
    }
  }
}