libc.obj: add atexit and normal exit. add exit code save/read

programs/develop/ktcc/trunk/libc.obj/source/stdlib/_exit.c

@@ -0,0 +1,29 @@
+#include <conio.h>
+#include <stdio.h>
+#include <sys/ksys.h>
+#include "_exit.h"
+
+void _exit(int status)
+{
+    __libc_exit(status, NULL);
+}
+
+void __libc_exit(int status, void (*before_exit)(int status))
+{
+    // return error and this is not abort
+    if (status && status != 128) {
+        fprintf(stderr, "\nexit code: %d\n", status);
+    }
+
+    WRITE_EXIT_CODE(status);
+
+    if (before_exit) {
+        before_exit(status);
+    }
+
+    if (__con_is_load) {
+        con_exit(0);
+    }
+
+    _ksys_exit();
+}