Index: common/include/printf_core.h
===================================================================
--- common/include/printf_core.h	(revision e0d874b77614e27ea09fe1f3f22e0f6239be9b17)
+++ common/include/printf_core.h	(revision e0d874b77614e27ea09fe1f3f22e0f6239be9b17)
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2006 Josef Cejka
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libc
+ * @{
+ */
+/** @file
+ */
+
+#ifndef _LIBC_PRINTF_CORE_H_
+#define _LIBC_PRINTF_CORE_H_
+
+#include <stddef.h>
+#include <stdarg.h>
+#include <uchar.h>
+
+/** Structure for specifying output methods for different printf clones. */
+typedef struct {
+	/* String output function, returns number of printed characters or EOF */
+	int (*str_write)(const char *, size_t, void *);
+
+	/* Wide string output function, returns number of printed characters or EOF */
+	int (*wstr_write)(const char32_t *, size_t, void *);
+
+	/* User data - output stream specification, state, locks, etc. */
+	void *data;
+} printf_spec_t;
+
+extern int printf_core(const char *, printf_spec_t *, va_list);
+
+#endif
+
+/** @}
+ */