/* encode_stub.c - Don Yang (uguu.org)

   08/25/12
                                                                           */

#include<stdio.h>

typedef unsigned int word;

static word result[256], result_count;
static word mm[256], aa, bb, cc;
static word i, j, w, x, y;

#if 1
static word seed[] = { 86, 0 };
static char data[] = "0123456789\n\0";
#else
static word seed[] = { 0 };
static char data[] =
   "The chaos that always crawls up to you with a smile, Nyarlathotep\n";
#endif

static word Isaac()
{
   if( !result_count-- )
   {
      bb += ++cc;
      for(i = 0; i < 256; bb = result[i++] = mm[(y >> 10) & 255] + x)
      {
         aa ^= (i & 1) ? aa >> ((i & 2) ? 16 : 6)
                       : aa << ((i & 2) ? 2 : 13);
         x = mm[i];
         y = mm[i] = mm[(x >> 2) & 255] + (aa += mm[(i + 128) & 255]) + bb;
      }
      result_count = 255;
   }
   return result[result_count];
}

static void Init()
{
   for(j = 0; j < 256; mm[j++] = 0);
   for(j = 0; j < sizeof(seed) / sizeof(word); j++)
      mm[j & 255] ^= seed[j];
   for(aa = bb = cc = result_count = j = 0; j < 1 << 24; j++)
      Isaac();
   j = w = 0;
}

static void EncodeBlock(word block)
{
   char buffer[5];
   word i, x;

   block ^= Isaac();
   for(i = 5; i != 0;)
   {
      x = block % 85;
      block /= 85;
      buffer[--i] = (x <= 31 ? x + 95 : x + 6);
   }
   fwrite(buffer, 5, 1, stdout);
}

static void Encode()
{
   char *input;
   word block, block_size;

   /* Encode input 4 bytes at a time */
   block = block_size = 0;
   for(input = data; *input != '\0'; input++)
   {
      block |= ((*input) & 0xff) << (8 * block_size);
      block_size++;
      if( block_size == 4 )
      {
         EncodeBlock(block);
         block = block_size = 0;
      }
   }

   /* Encode final block */
   if( block_size != 0 )
   {
      EncodeBlock(block);
      putchar(block_size == 1 ? '!' :
              block_size == 2 ? '%' :
                                '$');
   }
   else
   {
      putchar('#');
   }
   putchar('\n');
}

int main()
{
   Init();
   Encode();
   return 0;
}