-// ----------------------------------------------------------------------------
-// $Id$
-// ----------------------------------------------------------------------------
-// Public Domain C Library - http://pdclib.sourceforge.net
-// This code is Public Domain. Use, modify, and redistribute at will.
-// ----------------------------------------------------------------------------
-
-int ungetc( int c, FILE * stream ) { /* TODO */ };
+/* $Id$ */
+
+/* ungetc( int, FILE * )
+
+ This file is part of the Public Domain C Library (PDCLib).
+ Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <stdio.h>
+
+#ifndef REGTEST
+
+int ungetc( int c, struct _PDCLIB_file_t * stream )
+{
+ if ( c == EOF || stream->ungetidx == _PDCLIB_UNGETCBUFSIZE )
+ {
+ return -1;
+ }
+ return stream->ungetbuf[stream->ungetidx++] = (unsigned char) c;
+}
+
+#endif
+
+#ifdef TEST
+#include <_PDCLIB_test.h>
+
+int main( void )
+{
+ /* Testing covered by ftell.c */
+ return TEST_RESULTS;
+}
+
+#endif