Added functions sanei_pp_set_datadir() and sanei_pp_uses_directio().

Added some documentation.

include/sane/sanei_pp.h

@@ -58,70 +58,89 @@ enum sanei_pp_mode {
 	SANEI_PP_MODE_ECP  = (1<<8)
 };
 
+#define SANEI_PP_DATAIN  1
+#define SANEI_PP_DATAOUT 0
+
 /** Initialize sanei_pp.
  *
  * This function must be called before any other sanei_pp function.
  */
 extern SANE_Status sanei_pp_init( void );
 
-/**
- * Function to open a parport device. 
+/** Open a parport device. 
  *
- * @param dev -
- * @param fd  -
+ * @param dev - name of device to open.
+ * @param fd  - pointer to variable that should revceive the handle.
  * @return
  */
 extern SANE_Status sanei_pp_open( const char *dev, int *fd );
 
-/**
- * Function to close a previously opened parport device.
+/* Close a previously opened parport device.
  *
  * @param fd - handle of the device to close
  */
 extern void sanei_pp_close( int fd );
 
-/**
- * Function to claim a parport device
+/** Claim a parport device
  *
  * @param fd - handle of the device to claim
  * @return 
  */
 extern SANE_Status sanei_pp_claim( int fd );
 
-/**
- * Function to release a previously claimed device
+/** Release a previously claimed device
  *
  * @param fd - handle of the device to release
  * @return
  */
 extern SANE_Status sanei_pp_release( int fd );
 
-/**
- * @param fd   -
- * @param mode -
- * @return
+/** Set the data direction
+ *
+ * @param fd  - handle of the device, where to change the direction.
+ * @param rev -
+ * @return SANE_STATUS_GOOD on success
  */
-extern SANE_Status sanei_pp_getmode( int fd, int *mode );
+extern SANE_Status sanei_pp_set_datadir( int fd, int rev );
 
-/**
- * @param fd  -
- * @param val -
- * @return
+/** Check whether for libieee1284 usage.
+ *
+ * This function can be used to check if the lib uses libieee1284 or
+ * in/out functions directly.
+ *
+ * @return SANE_TRUE if we use direct access, SANE_FALSE if the lib uses
+ *         libieee1284 functions.
+ */
+extern SANE_Bool sanei_pp_uses_directio( void );
+
+/** Determine the available parallel port modes for a given device.
+ *
+ * @param fd   - handle of the device, whose modes shall be checked for.
+ * @param mode - pointer to variable, which should receive the modes.
+ * @return SANE_STATUS_GOOD on success.
+ */
+extern SANE_Status sanei_pp_getmodes( int fd, int *mode );
+
+/** Write data to ports (spp-data, ctrl and epp-address)
+ *
+ * @param fd  - handle of device to which shall be written to.
+ * @param val - data to write.
+ * @return SANE_STATUS_GOOD on success.
  */
 extern SANE_Status sanei_pp_outb_data( int fd, SANE_Byte val );
 extern SANE_Status sanei_pp_outb_ctrl( int fd, SANE_Byte val );
 extern SANE_Status sanei_pp_outb_addr( int fd, SANE_Byte val );
 
-/**
- * @param fd -
- * @return
+/** Read data from ports (spp-data, status, ctrl and epp-data)
+ * @param fd - handle of device who should be read from.
+ * @return value got from port
  */
 extern SANE_Byte sanei_pp_inb_data( int fd );
 extern SANE_Byte sanei_pp_inb_stat( int fd );
 extern SANE_Byte sanei_pp_inb_ctrl( int fd );
 extern SANE_Byte sanei_pp_inb_epp ( int fd );
 
-/** function to delay execution for some micro-seconds.
+/** Delay execution for some micro-seconds.
  *  Please not, that the accuracy highly depends on your system architechture
  *  and the time to delay. It is internally implemented as system calls to
  *  gettimeofday().