#define NOCCARG
#include stdio.h
#include clib.def
extern int *_auxsz, *_auxef, _auxrd, _auxwt, _auxfl, _status[];
/*
** Loaded only if auxbuf() is called.  Longer explanation in DDJ.
*/
int
  _xsize[MAXFILES],  /*size of buffer*/
  _xaddr[MAXFILES],   /*aux buffer address*/
  _xnext[MAXFILES],   /*address of next byte in buffer*/
  _xend[MAXFILES],    /*address of end-of-data in buffer*/
  _xeof[MAXFILES];    /*true if current buffer ends file*/
/*
** auxbuf(fd, size) -- allocate an auxiliary buffer of size size for
** fd fd.  Longer explanation in DDJ.
*/
auxbuf(fd, size) int fd; char *size; {  /*fake unsigned*/
  if(!_mode(fd) || size || avail(NO) < size || _xsize[fd])
    return (ERR);
  _xaddr[fd] = _xnext[fd] = _xend[fd] = malloc(size);
  _auxef = _xeof;  /*pass locations to i/o routines*/
  _auxrd =  _xread;
  _auxwt = _xwrite;
  _auxsz = _xsize;
  _auxfl = _xflush;
  _xsize[fd] = size;
  return (NULL);
  }

/*
** Fill buffer if necessary, and return next byte.
*/
_xread(fd) int fd; {
  char *ptr;
  while(YES) {
    ptr = _xnext[fd];
    if(ptr < _xend[fd]) {++_xnext[fd]; return (*ptr);}
    if(_xeof[fd]) {_seteof(fd); return (EOF);}
    _auxsz = NULL;    /*avoid recursive loop*/
    _xend[fd] = _xaddr[fd] 
                + read(fd, _xnext[fd]=_xaddr[fd], _xsize[fd]);
    _auxsz = _xsize;  /*restore _auxsz*/
    if(feof(fd)) {_xeof[fd] = YES; _clreof(fd);}
    }
  }

/*
** Empty buffer if necessary, and store ch in buffer.
*/
_xwrite(ch, fd) int ch, fd; {
  char *ptr;
  while(YES) {
    ptr = _xnext[fd];
    if(ptr < (_xaddr[fd] + _xsize[fd]))
      {*ptr = ch; ++_xnext[fd]; return (ch);}
    if(_xflush(fd)) return (EOF);
    }
  }

/*
** Flush aux buffer to file.
*/
_xflush(fd) int fd; {
  int i, j;
  i = _xnext[fd] - _xaddr[fd];
  _auxsz = NULL;  /*avoid recursive loop*/
  j = write(fd, _xnext[fd]=_xaddr[fd], i);
  _auxsz = _xsize; /*restore _auxsz*/
  if(i != j) return (EOF);
  return (NULL);
  }