lib/libc/stdio/ungetc.c

   1 /*
   2  * ungetc.c - push a character back onto an input stream
   3  */
   4 /* $Header$ */
   5
   6 #include        <stdio.h>
   7 #include        "loc_incl.h"
   8
   9 int
  10 ungetc(int ch, FILE *stream)
  11 {
  12         unsigned char *p;
  13
  14         if (ch == EOF  || !io_testflag(stream,_IOREADING))
  15                 return EOF;
  16         if (stream->_ptr == stream->_buf) {
  17                 if (stream->_count != 0) return EOF;
  18                 stream->_ptr++;
  19         }
  20         stream->_count++;
  21         p = --(stream->_ptr);           /* ??? Bloody vax assembler !!! */
  22         /* ungetc() in sscanf() shouldn't write in rom */
  23         if (*p != (unsigned char) ch)
  24                 *p = (unsigned char) ch;
  25         return ch;
  26 }