+/* Parsing any fopen() style filemode string into a number of flags. */
+unsigned int _PDCLIB_filemode( const char * mode );
+
+/* Sanity checking and preparing of read buffer, should be called first thing
+ by any stdio read-data function.
+ Returns 0 on success, EOF on error.
+ On error, EOF / error flags and errno are set appropriately.
+*/
+int _PDCLIB_prepread( struct _PDCLIB_file_t * stream );
+
+/* Sanity checking, should be called first thing by any stdio write-data
+ function.
+ Returns 0 on success, EOF on error.
+ On error, error flags and errno are set appropriately.
+*/
+int _PDCLIB_prepwrite( struct _PDCLIB_file_t * stream );
+
+/* Closing all streams on program exit */
+void _PDCLIB_closeall( void );
+
+/* -------------------------------------------------------------------------- */
+/* errno */
+/* -------------------------------------------------------------------------- */
+
+extern int _PDCLIB_errno;
+int * _PDCLIB_errno_func( void );
+
+/* ERANGE and EDOM are specified by the standard. */
+#define _PDCLIB_ERANGE 1
+#define _PDCLIB_EDOM 2
+/* Used in the example implementation for any kind of I/O error. */
+#define _PDCLIB_EIO 3
+/* Used in the example implementation for "unknown error". */
+#define _PDCLIB_EUNKNOWN 4
+/* Used in the example implementation for "invalid parameter value". */
+#define _PDCLIB_EINVAL 5
+/* Used in the example implementation for "I/O retries exceeded". */
+#define _PDCLIB_ERETRY 6
+/* One larger than the largest used errno */
+#define _PDCLIB_EMAX 7
+
+/* TODO: Doing this via a static array is not the way to do it. */
+char const * _PDCLIB_errno_texts[ _PDCLIB_EMAX ];
+
+/* -------------------------------------------------------------------------- */
+/* <ctype.h> lookup tables */
+/* -------------------------------------------------------------------------- */
+
+#define _PDCLIB_CTYPE_ALPHA 1
+#define _PDCLIB_CTYPE_BLANK 2
+#define _PDCLIB_CTYPE_CNTRL 4
+#define _PDCLIB_CTYPE_GRAPH 8
+#define _PDCLIB_CTYPE_PUNCT 16
+#define _PDCLIB_CTYPE_SPACE 32
+#define _PDCLIB_CTYPE_LOWER 64
+#define _PDCLIB_CTYPE_UPPER 128
+#define _PDCLIB_CTYPE_DIGIT 256
+#define _PDCLIB_CTYPE_XDIGT 512
+
+struct _PDCLIB_ctype_t
+{
+ _PDCLIB_uint16_t flags;
+ unsigned char upper;
+ unsigned char lower;
+ unsigned char collation;
+};