/* Last edited on 2006-08-22 09:50:56 by stolfi */
/* Converts MIME quote-printable encoding to binary bytes. */

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

int doit(void);

int main(int argc, char **argv)
{
  int res;
  if (argc != 1) 
    { fprintf(stderr, "unquote-printable: no args please\n"); return(1); }
  res = doit();
  fclose(stdout);
  return(res);
}
  
#define ERROR(msg) \
  fprintf(stderr, "unquote-printable: byte %d: %s\n", nc, msg); return(1)

int doit(void)
{
  int c, a, b;
  int nc = 0;
  int hexval[256];
  /* Hexadecimal digit value table */
  for (c=0; c<256; c++) { hexval[c] = -1; }
  for (c='0'; c<= '9'; c++) { hexval[c] = c - '0'; }
  for (c='A'; c<= 'F'; c++) { hexval[c] = 10 + (c - 'A'); }
  for (c='a'; c<= 'f'; c++) { hexval[c] = 10 + (c - 'a'); }
  /* Mapping */
  c = getchar();
  while (c != EOF) 
    { nc++;
      if ( c == '=' ) 
        { a = getchar();
          if (a == EOF) { ERROR("unexpected EOF"); }
          nc++;
          if (a == '\n')
            { c = '\n'; }
          else
            { b = getchar();
              if (b == EOF) { ERROR("unexpected EOF"); } 
              nc++;
              a = hexval[a];
              b = hexval[b];
              if ((a == -1) || (b == -1)) { ERROR("bad hex digit"); }
              c = ((a << 4) | b);
            }
        }
      if (putchar(c) == EOF) { ERROR("problem writing stdout"); }
      c = getchar();
    }
  return(0);
}