/* atob: version 4.0
 * stream filter to change printable ascii from "btoa" back into 8 bit bytes
 * if bad chars, or Csums do not match: exit(1) [and NO output]
 *
 *  Paul Rutter		Joe Orost
 *  philabs!per		petsd!joe
 *
 * Hacked on somewhat by der Mouse to (a) remove ASCII dependency, (b) port
 *  to gcc -Wstrict-prototypes -Wmissing-prototypes, and (c) generally clean
 *  up the code.  It should now work right on >32-bit machines.
 */

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <strings.h>

extern char *__progname;

#include "common.h"

static unsigned long int word = 0;
static int bcount = 0;

static int fast_way = -1;

static FILE *outf;

static void fatal(const char *fmt, ...)
{
 va_list ap;

 fprintf(stderr,"%s: invalid input file (",__progname);
 va_start(ap,fmt);
 vfprintf(stderr,fmt,ap);
 va_end(ap);
 fprintf(stderr,")\n");
 exit(1);
}

static void byteout(int c)
{
 dochecksum(c);
 putc(c,outf);
}

static void decode(int ch)
{
 if (fast_way < 0)
  { int i;
    for (i=1;digits[i];i++) if (digits[i-1] != digits[i]-1) break;
    fast_way = !digits[i];
  }
 if (ch == zdig)
  { if (bcount != 0)
     { fatal("zero on wrong boundary");
     }
    else
     { byteout(0);
       byteout(0);
       byteout(0);
       byteout(0);
     }
  }
 else
  { int d;
    if (fast_way)
     { d = ch - digits[0];
       if ((d < 0) || (d >= 85))
	{ fatal("invalid digit (%c)",ch);
	}
     }
    else
     { const char *dp;
       dp = index(&digits[0],ch);
       if (! dp) fatal("invalid digit (%c)",ch);
       d = dp - &digits[0];
     }
    switch (bcount)
     { case 0:
	  word = d;
	  bcount ++;
	  break;
       case 1: case 2: case 3:
	  word = (word * 85) + d;
	  bcount ++;
	  break;
       default:
	  word = (word * 85) + d;
	  byteout((word>>24)&0xff);
	  byteout((word>>16)&0xff);
	  byteout((word>> 8)&0xff);
	  byteout((word    )&0xff);
	  bcount = 0;
	  break;
     }
  }
}

int main(int, char **);
int main(int ac, char **av)
{
 int force;
 char buf[100];
 int ch;

 if ((ac > 1) && !strcmp(av[1],"-f"))
  { force = 1;
    ac --;
    av ++;
  }
 else
  { force = 0;
  }
 if (ac != 1)
  { fprintf(stderr,"%s: bad args (usage: %s [-f])\n",__progname,__progname);
    exit(1);
  }
 if (force)
  { outf = stdout;
  }
 else
  { outf = tmpfile();
    if (outf == 0) fatal("can't open temp file");
  }
 do
  { if (fgets(&buf[0],sizeof(buf),stdin) != &buf[0]) fatal("no header line found");
  } while (strcmp(&buf[0],"xbtoa Begin\n"));
 while ((ch=getchar()) != EOF)
  { if (ch == '\n')
     { continue;
     }
    else if (ch == endmarker)
     { break;
     }
    else
     { decode(ch);
     }
  }
 if (! force)
  { long int n1;
    long int n2;
    long int oeor;
    long int osum;
    long int orot;
    if (scanf("btoa End N %ld %lx E %lx S %lx R %lx\n",
				&n1,&n2,&oeor,&osum,&orot) != 5)
     { fatal("ending line mangled");
     }
    if ((n1 != n2) || (oeor != Ceor) || (osum != Csum) || (orot != Crot))
     { fatal("checksum mismatch");
     }
    rewind(outf);
    for (;n1>0;n1--)
     { putchar(getc(outf));
     }
  }
 exit(0);
}