-// ----------------------------------------------------------------------------
-// $Id$
-// ----------------------------------------------------------------------------
-// Public Domain C Library - http://pdclib.sourceforge.net
-// This code is Public Domain. Use, modify, and redistribute at will.
-// ----------------------------------------------------------------------------
-
-// TODO: C/C++ linkages
-int atexit( void (*func) ( void ) ) { /* TODO */ };
+/* atexit( void (*)( void ) )
+
+ This file is part of the Public Domain C Library (PDCLib).
+ Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <stdlib.h>
+
+#ifndef REGTEST
+
+extern void (*_PDCLIB_exitstack[])( void );
+extern size_t _PDCLIB_exitptr;
+
+int atexit( void (*func)( void ) )
+{
+ if ( _PDCLIB_exitptr == 0 )
+ {
+ return -1;
+ }
+ else
+ {
+ _PDCLIB_exitstack[ --_PDCLIB_exitptr ] = func;
+ return 0;
+ }
+}
+
+#endif
+
+#ifdef TEST
+
+#include "_PDCLIB_test.h"
+
+#include <assert.h>
+
+static int flags[ 32 ];
+
+static void counthandler( void )
+{
+ static int count = 0;
+ flags[ count ] = count;
+ ++count;
+}
+
+static void checkhandler( void )
+{
+ for ( int i = 0; i < 31; ++i )
+ {
+ assert( flags[ i ] == i );
+ }
+}
+
+int main( void )
+{
+ TESTCASE( atexit( &checkhandler ) == 0 );
+ for ( int i = 0; i < 31; ++i )
+ {
+ TESTCASE( atexit( &counthandler ) == 0 );
+ }
+ return TEST_RESULTS;
+}
+
+#endif