#include "Charliplexing.h" #include "kbd.h" #include #include #include #include typedef struct _point_t { uint8_t x, y; } point_t; typedef enum _dir_t { NORTH = 0, WEST, SOUTH, EAST } dir_t; static volatile uint8_t kbdir; static volatile bool start; static volatile uint16_t lfsr = 0xace1; static uint8_t dir; static point_t tail = {7, 4}; #define HISTORY_MAX 128 static uint8_t history[HISTORY_MAX >> 2]; static uint8_t history_len = 0; static uint8_t history_pos = 0; static point_t q; static uint16_t rand(void) { unsigned bit; /* taps: 16 14 13 11; feedback polynomial: x^16 + x^14 + x^13 + x^11 + 1 */ bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 5)) & 1; lfsr = (lfsr >> 1) | (bit << 15); return lfsr; } static void rand_mix(uint16_t mix) { lfsr ^= mix; rand(); } static void rand_q(void) { q.x = rand() % 14; q.y = rand() % 9; } static inline uint8_t rev(uint8_t d) { return d ^ 2; } static inline bool points_equal(const point_t *p1, const point_t *p2) { return p1->x == p2->x && p1->y == p2->y; } static void move(uint8_t d, bool grow) { uint8_t p = (history_pos+history_len) % HISTORY_MAX; uint8_t n = p >> 2, shift = (p & 3) << 1; history[n] &= ~(3 << shift); history[n] |= d << shift; if (grow) history_len++; else history_pos = (history_pos+1) % HISTORY_MAX; } static uint8_t get_dir(uint8_t i) { uint8_t p = (history_pos+i) % HISTORY_MAX; uint8_t n = p >> 2, shift = (p & 3) << 1; return (history[n] >> shift) & 3; } static void reset(void) { LedSignClear(0); rand_q(); kbdir = dir = EAST; tail = (point_t){7, 4}; history_len = 0; history_pos = 0; unsigned i; for (i = 0; i < 2; i++) move(EAST, true); } static void set_led(uint8_t x, uint8_t y, uint8_t val) { LedSignSet(13-x, 8-y, val); } void kbd_handle(uint16_t code, bool make) { if (!make) return; switch(code) { case KBD_CODE_SPACE: start = true; break; case KBD_CODE_UP: kbdir = NORTH; break; case KBD_CODE_LEFT: kbdir = WEST; break; case KBD_CODE_DOWN: kbdir = SOUTH; break; case KBD_CODE_RIGHT: kbdir = EAST; } } static void go(point_t *point, uint8_t d) { switch (d) { case NORTH: point->y = (point->y+8)%9; break; case WEST: point->x = (point->x+13)%14; break; case SOUTH: point->y = (point->y+1)%9; break; case EAST: point->x = (point->x+1)%14; } } static bool point_used(const point_t *p, bool head) { point_t pt = tail; unsigned i; for (i = 0; i < history_len - (head ? 0 : 1); i++) { go(&pt, get_dir(i)); if (points_equal(&pt, p)) return true; } return false; } static bool step(void) { if (kbdir != rev(dir)) dir = kbdir; uint8_t d = dir; rand_mix(d); set_led(tail.x, tail.y, 0); int i; point_t pt = tail; set_led(pt.x, pt.y, 0); for (i = 0; i < history_len; i++) { go(&pt, get_dir(i)); set_led(pt.x, pt.y, 2); } go(&pt, d); set_led(pt.x, pt.y, 3); if (point_used(&pt, true)) return false; if (points_equal(&pt, &q)) { rand_q(); move(d, true); } else { go(&tail, get_dir(0)); move(d, false); } if (point_used(&pt, false)) return false; set_led(q.x, q.y, 7); return true; } int main() { LedSignInit(GRAYSCALE); kbd_init(); sei(); kbd_send(KBD_CMD_RESET); while(true) { start = false; while (!start) {} reset(); while (step()) _delay_ms(100); } return 0; }