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

   12/01/01
                                                                           */

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


static void WriteBits(int n, int b, FILE *outfile);
static void WriteByte(int x, FILE *outfile);

/******************************************************************** main */
int main(int argc, char **argv)
{
   char data[8192];
   FILE *infile, *outfile;
   int i, j, k, runlength, size;
   int maxduplength, maxdupoffset;

   infile = stdin;
   outfile = stdout;
   if( argc > 1 )
   {
      if( (infile = fopen(argv[1], "rt")) == NULL )
         return printf("Can not open %s\n", argv[1]);
      if( argc > 2 )
      {
         if( (outfile = fopen(argv[2], "wt+")) == NULL )
         {
            (void)fclose(infile);
            return printf("Can not create %s\n", argv[2]);
         }
      }
   }

   size = 0;
   memset(data, 0, 8192);
   while( (i = fgetc(infile)) != EOF )
      data[1024 + size++] = (char)i;


   for(i = runlength = 0; i < size; i++)
   {
      maxduplength = 4;
      maxdupoffset = 0;
      for(j = -30; j < 0; j++)
      {
         for(k = 0; k < -j; k++)
         {
            if( data[1024 + i + k] != data[1024 + i + j + k] )
               break;
         }
         if( k > maxduplength )
         {
            maxdupoffset = j;
            maxduplength = k;
         }
      }
      if( maxduplength > 4 )
      {
         if( runlength > 0 )
         {
            fprintf(outfile, "%4d: Run = %d characters\n",
               i - runlength, runlength);
            WriteBits(1, 1, outfile);
            WriteBits(runlength, 5, outfile);
            for(j = 0; j < runlength; j++)
               WriteByte((int)data[1024 + i + j - runlength], outfile);
            runlength = 0;
         }

         fprintf(outfile, "%4d: Duplicate = %d characters, offset = %d\n",
            i, maxduplength, maxdupoffset);
         i += maxduplength - 1;
         WriteBits(0, 1, outfile);
         WriteBits(maxduplength, 5, outfile);
         WriteBits(-maxdupoffset, 5, outfile);
      }
      else
      {
         runlength++;
         if( runlength > 30 )
         {
            fprintf(outfile, "%4d: Run = %d characters\n",
               i + 1 - runlength, runlength);
            WriteBits(1, 1, outfile);
            WriteBits(runlength, 5, outfile);
            for(j = 0; j < runlength; j++)
               WriteByte((int)data[1024 + i + 1 + j - runlength], outfile);
            runlength = 0;
         }
      }
   }
   if( runlength > 0 )
   {
      fprintf(outfile, "%d: Run = %d characters\n", i - runlength, runlength);
      WriteBits(1, 1, outfile);
      WriteBits(runlength, 5, outfile);
      for(j = 0; j < runlength; j++)
         WriteByte((int)data[1024 + i + j - runlength], outfile);
   }

   (void)fclose(infile);
   (void)fclose(outfile);
   return 0;

} /* main() */

/*************************************************************** WriteBits */
static void WriteBits(int n, int b, FILE *outfile)
{
   int i;

   (void)fputs("      ", outfile);
   for(i = 0; i < b; i++)
      (void)fputc((n & (1 << (b - i - 1))) == 0 ? '0' : '1', outfile);
   (void)fputc('\n', outfile);

} /* WriteBits() */

/*************************************************************** WriteByte */
static void WriteByte(int x, FILE *outfile)
{
   static char dict[8] = ",.`':\"\nx";
   int i;

   if( x == (int)' ' )
   {
      WriteBits(0, 1, outfile);
   }
   else if( x == (int)'%' || x == (int)'X' )
   {
      WriteBits(1, 1, outfile);
      WriteBits(0, 1, outfile);
      WriteBits(x == (int)'%' ? 0 : 1, 1, outfile);
   }
   else
   {
      WriteBits(1, 1, outfile);
      WriteBits(1, 1, outfile);
      for(i = 0; i < 8 && dict[i] != (char)x; i++);
      WriteBits(i, 3, outfile);
   }

} /* WriteBits() */