Square movement

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <tice.h>

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <graphx.h>
#include <keypadc.h>

void main(void) {
    uint16_t x = 0;
    uint8_t y = 0;
    uint8_t key;
    bool running = true;
    prgm_CleanUp();
    gfx_Begin();
    gfx_SetDrawBuffer();
    gfx_ZeroScreen();
    gfx_SetColor(255);
    gfx_FillRectangle(x, y, 20, 20);
    gfx_BlitBuffer();
    while(running) {
        key = kb_ScanGroup(kb_group_6);
        if (key == kb_Clear) running = false;
        key = kb_ScanGroup(kb_group_7);
        switch(key) {
            case kb_Up:
                y--;
                break;
            case kb_Down:
                y++;
                break;
            case kb_Left:
                x--;
                break;
            case kb_Right:
                x++;
                break;
        }
        if (key) {
            gfx_ZeroScreen();
            gfx_SetColor(255);
            gfx_FillRectangle(x, y, 20, 20);
            gfx_BlitBuffer();
        }
    }
    gfx_End();
}