/*----------------------------------------------------*/
/* qpdecode.c --   QuotedPrintable-Decoding Filter    */
/*----------------------------------------------------*/
/*  Usage:                                            */
/*    qpdecode [infile] > <file>                      */
/*        infile: filename of the file to be decoded  */
/*                (if omitted, input from stdin)      */
/*     result(stdout) should be redirected to <file>  */
/*----------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

int main(int argc, char *argv[])
{ int c, b; FILE *fp;
# ifdef O_BINARY
  setmode(1,O_BINARY);
# endif
  if (argc == 1) {
    fp = stdin;
# ifdef O_BINARY
    setmode(0,O_BINARY);
# endif
  } else if ((fp=fopen(argv[1],"rb")) == NULL) {
    fprintf(stderr, "file %s not found\n", argv[1]); exit(1);
  }
  while ((c=getc(fp)) != EOF) {
    if (c == '=') {
      if ((b=getc(fp)) == EOF) { printf("=\n"); break; }
      if (b == 0x0D) {
        if ((c=getc(fp)) == EOF) { printf("=[CR]\n");  break; }
        if (c != 0x0A) { ungetc(c, fp); printf("=[CR]"); }
      } else if (b == 0x0A) {
      } else if ((0x30 <= b  &&  b <= 0x39) ||
                 (0x41 <= b  &&  b <= 0x46) ||
                 (0x61 <= b  &&  b <= 0x66)) {
        if ((c=getc(fp)) == EOF) { printf("=%c\n", b);  break; }
        if ((0x30 <= c  &&  c <= 0x39) ||
            (0x41 <= c  &&  c <= 0x46) ||
            (0x61 <= c  &&  c <= 0x66)) {
          if (b < 0x41) b = b-0x30;
          else b = ((b < 0x61)? b-0x37: b-0x57);
          if (c < 0x41) c = c-0x30;
          else c = ((c < 0x61)? c-0x37: c-0x57);
          c = b*16 + c; putchar(c);
        } else {
          ungetc(c, fp); printf("=%c", b);
        }
      } else {
        ungetc(c, fp); putchar('=');
      }
    } else {
      putchar(c);
    }
  }
  fclose(fp); fclose(stdout);
  return(0);
}