A braille spinner animation

braille-main.c

#include <stdio.h>
#include <unistd.h>



unsigned int  braille_unicode_from_4x2_bytemap( char map[4][2])
{
    unsigned int pattern = 0;

    // Map dots to their corresponding bit positions in Braille
    // Standard Braille dot positions are:
    // 1 4    dot 1 = 0x01, dot 4 = 0x08
    // 2 5    dot 2 = 0x02, dot 5 = 0x10
    // 3 6    dot 3 = 0x04, dot 6 = 0x20
    // 7 8    dot 7 = 0x40, dot 8 = 0x80

    if( map[ 0][ 0] > 0) pattern |= 0x01;  // dot 1
    if( map[ 1][ 0] > 0) pattern |= 0x02;  // dot 2
    if( map[ 2][ 0] > 0) pattern |= 0x04;  // dot 3
    if( map[ 0][ 1] > 0) pattern |= 0x08;  // dot 4
    if( map[ 1][ 1] > 0) pattern |= 0x10;  // dot 5
    if( map[ 2][ 1] > 0) pattern |= 0x20;  // dot 6
    if( map[ 3][ 0] > 0) pattern |= 0x40;  // dot 7
    if( map[ 3][ 1] > 0) pattern |= 0x80;  // dot 8

    // Convert to UTF-8
    return( 0x2800 + pattern);  // 0x2800 is the Unicode Braille Pattern base
}


static unsigned int   x_values[ 8] =
{
   0, 1, 1, 1, 1, 0, 0, 0
};


static unsigned int   y_values[ 8] =
{
   0, 0, 1, 2, 3, 3, 2, 1
};


static void   get_x_y_from_i( unsigned int i, unsigned int *x, unsigned int *y)
{
   i &= 0x7;
   *x = x_values[ i];
   *y = y_values[ i];
}


static void   init_4x2_bytemap( char map[4][2], unsigned int i)
{
   unsigned int  cycle;

   memset( map, 0, 8);

   cycle = i / 16;
   cycle = cycle & 0xF;

   if( cycle >= 8)
      cycle = 15 - cycle;

   switch( cycle & 0x7)
   {
   case 7 : map[ 0][ 1] = 0x1;
   case 6 : map[ 1][ 1] = 0x1;
   case 5 : map[ 2][ 1] = 0x1;
   case 4 : map[ 3][ 1] = 0x1;
   case 3 : map[ 3][ 0] = 0x1;
   case 2 : map[ 2][ 0] = 0x1;
   case 1 : map[ 1][ 0] = 0x1;
   case 0 : break;
   }
}

static void   animate_4x2_bytemap( char map[4][2], unsigned int i)
{
   unsigned int  x, y;

   if( (i & 0x7) == 0)
   {
      init_4x2_bytemap( map, i);
   }
   else
   {
      get_x_y_from_i( i - 1, &x, &y);
      map[ y][ x] ^= 0x1;
   }

   get_x_y_from_i( i, &x, &y);
   map[ y][ x] ^= 0x1;
}


int main(int argc, char *argv[])
{
   unsigned int    i = 0;
   char            map[ 4][ 2] = { 0 };
   char            utf8[ 4];
   unsigned int    unicode;

   // Hide cursor
   printf("\033[?25l");

   while( 1)
   {
      animate_4x2_bytemap( map, i);

      unicode = braille_unicode_from_4x2_bytemap( map);
      utf8[0] = 0xE0 | (unicode >> 12);
      utf8[1] = 0x80 | ((unicode >> 6) & 0x3F);
      utf8[2] = 0x80 | (unicode & 0x3F);
      utf8[3] = '\0';

      printf("\r%s  %u", utf8, i);
      fflush(stdout);
      usleep(50000);  

      ++i;
   }
   
   printf("\033[?25h");
   return 0;
}