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

#define  BUFSIZE 0x1000000
#define  BUFLOW  0x400
static          int  infile = -1;
static unsigned char  nblock[ BUFSIZE + 16 ];
static unsigned char*inblock = nblock + 16;
static unsigned long inblockoffs = 0;

static unsigned long infilesize = 0;
static unsigned long infileoffs = 0;
static unsigned char to_lower[];
static unsigned char run = 1;

static void buffer_lowwatermark( void )
{
  int i;
  if( infilesize - infileoffs < BUFSIZE )
    return;
  memmove( inblock, inblock + inblockoffs, BUFSIZE - inblockoffs );
  read( infile, inblock + (BUFSIZE - inblockoffs), inblockoffs);
  for ( i = BUFSIZE - inblockoffs; i<BUFSIZE; ++i) inblock[i] = to_lower[inblock[i]];
  infileoffs += inblockoffs;
  inblockoffs = 0;
}

static void buffer_init( void )
{
  int i;
  read( infile, inblock, BUFSIZE);
  for ( i = 0; i<BUFSIZE; ++i) inblock[i] = to_lower[inblock[i]];
}

static unsigned char to_lower[] = {
0x00, 0x01, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x01, 0x00, 0x02, 0x02, 0x02, 0x02, 0x02,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F,
0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F,
0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F,
0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F,
0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF,
0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF,
0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF,
0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xF6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xFC, 0xDD, 0xDE, 0xDF,
0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xEE, 0xEF,
0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF
};

int makefile( int currrow, unsigned char a, unsigned char b)
{
  int fid; char fn[16]; sprintf( fn, "%02d/%2X%2X", currrow, a, b);
  fid = open( fn, O_RDWR | O_CREAT, 0644 );
  if( fid == -1 ) {
    fprintf( stderr, "Unable to open: %s\n", fn );
    exit( 1 );
  }
  return fid;
}

int main( int args, char **argv )
{
  int currrow = 1, inrow = 0, nowfd, use, mycount = 0;
  unsigned long row;
  static int fd[0x10000][17];

  memset( fd, 0, sizeof(fd));
  setvbuf( stdout, NULL, _IONBF, 0);

  if( (args != 3) || ((row = atol(argv[1]))==0))
  {
    fprintf( stderr, "syntax: %s row toindex\n", *argv );
    exit( 1 );
  }

  if( ( infile = open( argv[2], O_RDONLY ) ) == -1 )
  {
    fprintf( stderr, "Could not open file %s.\n", argv[2] );
    exit( 1 );
  }
  getfilesize( infile, &infilesize );

  buffer_init();

  row = 1 << row;
  use = row & 1;
  while( 1 )
  {
    unsigned char a, b;
    switch( a = inblock[inblockoffs++] )
    {
      case   0 :
        currrow = 0;
        if( inblockoffs > BUFSIZE - BUFLOW )
          buffer_lowwatermark();
        if( infilesize <= infileoffs + inblockoffs)
          return 0;
        if( !(mycount++ & 255) )
          printf( "%cSo far: %010.6f%% (%010lu / %010lu)", 13, 100.00 * (double)(infileoffs+inblockoffs) / (double)infilesize, infileoffs+inblockoffs, infilesize );
        // Fall through
      case   1 :
        use = (1<<currrow) & row; currrow++; inrow = 0;
        break;
      default  :
        if( use && ( (b = inblock[inblockoffs] ) > 1 ) )
        {
          if( !fd[ b | (a*256) ][currrow] )
            nowfd = fd[ b | (a*256) ][currrow] = makefile( currrow, a, b);
          else
            nowfd = fd[ b | (a*256) ][currrow];

          *(unsigned long*)(inblock+inblockoffs-4) = infileoffs + inblockoffs - 1 - inrow;
                            inblock[inblockoffs]   = inrow++;
          write( nowfd,     inblock+inblockoffs-4, 16);
                            inblock[inblockoffs]   = b;
          break;
        }
    }
  }

  return 0;
}