Added optional support for Sparkfun SiGe GN3S USB GPS RF sampler:

- Added a pre-compiled custom GN3S firmware.
- Added a fully-compliant GNU Radio source block for GN3S USB dongle. It can be used also from GNU Radio companion and from Python applications.
- Added a new GN3S_Signal_Source block. It is possible to disable the GN3S signal source compilation. See README.

git-svn-id: https://svn.code.sf.net/p/gnss-sdr/code/trunk@217 64b25241-fba3-4117-9849-534c7e92360d

drivers/gr-gn3s/include/fusb_linux.h

@@ -0,0 +1,116 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2003 Free Software Foundation, Inc.
+ * 
+ * This file is part of GNU Radio
+ * 
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ * 
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+// Fast USB interface
+
+#ifndef _FUSB_LINUX_H_
+#define _FUSB_LINUX_H_
+
+#include "fusb.h"
+#include <list>
+
+struct  usbdevfs_urb;
+class   fusb_ephandle_linux;
+
+/*!
+ * \brief linux specific implementation of fusb_devhandle using usbdevice_fs
+ */
+class fusb_devhandle_linux : public fusb_devhandle {
+private:
+  std::list<usbdevfs_urb*>	 d_pending_rqsts;
+
+  void pending_add (usbdevfs_urb *urb);
+  bool pending_remove (usbdevfs_urb *urb);
+  usbdevfs_urb * pending_get ();
+
+
+public:
+  // CREATORS
+  fusb_devhandle_linux (usb_dev_handle *udh);
+  virtual ~fusb_devhandle_linux ();
+
+  // MANIPULATORS
+  virtual fusb_ephandle *make_ephandle (int endpoint, bool input_p,
+					int block_size = 0, int nblocks = 0);
+
+  // internal use only
+  bool _submit_urb (usbdevfs_urb *urb);
+  bool _cancel_urb (usbdevfs_urb *urb);
+  void _cancel_pending_rqsts (fusb_ephandle_linux *eph);
+  bool _reap (bool ok_to_block_p);
+  void _wait_for_completion ();
+};
+
+ /*!
+ * \brief linux specific implementation of fusb_ephandle using usbdevice_fs
+ */
+
+class fusb_ephandle_linux : public fusb_ephandle {
+private:
+  fusb_devhandle_linux	       *d_devhandle;
+  std::list<usbdevfs_urb*>	d_free_list;
+  std::list<usbdevfs_urb*>	d_completed_list;
+  usbdevfs_urb		       *d_write_work_in_progress;
+  unsigned char		       *d_write_buffer;
+  usbdevfs_urb		       *d_read_work_in_progress;
+  unsigned char		       *d_read_buffer;
+  unsigned char		       *d_read_buffer_end;
+
+  usbdevfs_urb *get_write_work_in_progress ();
+  void reap_complete_writes ();
+  bool reload_read_buffer ();
+  bool submit_urb (usbdevfs_urb *urb);
+  
+public:
+  fusb_ephandle_linux (fusb_devhandle_linux *dh, int endpoint, bool input_p,
+		       int block_size = 0, int nblocks = 0);
+  virtual ~fusb_ephandle_linux ();
+
+  virtual bool start ();  	//!< begin streaming i/o
+  virtual bool stop ();		//!< stop streaming i/o
+
+  /*!
+   * \returns \p nbytes if write was successfully enqueued, else -1.
+   * Will block if no free buffers available.
+   */
+  virtual int write (const void *buffer, int nbytes);
+
+  /*!
+   * \returns number of bytes read or -1 if error.
+   * number of bytes read will be <= nbytes.
+   * Will block if no input available.
+   */
+  virtual int read (void *buffer, int nbytes);
+
+  /*
+   * block until all outstanding writes have completed
+   */
+  virtual void wait_for_completion ();
+
+  // internal use only
+  void free_list_add (usbdevfs_urb *urb);
+  void completed_list_add (usbdevfs_urb *urb);
+  usbdevfs_urb *free_list_get (); 		// pop and return head of list or 0
+  usbdevfs_urb *completed_list_get ();		// pop and return head of list or 0
+};
+
+#endif /* _FUSB_LINUX_H_ */