[Patch-gnuradio] [PATCH 2/4] usrp: libusb-1.0 fusb

[Thomas Tsou]

Added fsub_libusb1.* to use asynchronous I/O through libusb-1.0 calls. Other 
API changes.

---
 usrp/host/lib/fusb.cc                   |    2 +-
 usrp/host/lib/fusb.h                    |   10 +-
 usrp/host/lib/fusb_libusb1.cc           |  679 +++++++++++++++++++++++++++++++
 usrp/host/lib/fusb_libusb1.h            |  127 ++++++
 usrp/host/lib/fusb_sysconfig_libusb1.cc |   49 +++
 5 files changed, 861 insertions(+), 6 deletions(-)
 create mode 100644 usrp/host/lib/fusb_libusb1.cc
 create mode 100644 usrp/host/lib/fusb_libusb1.h
 create mode 100644 usrp/host/lib/fusb_sysconfig_libusb1.cc

diff --git a/usrp/host/lib/fusb.cc b/usrp/host/lib/fusb.cc
index 6e4358f..ce4bb7a 100644
--- a/usrp/host/lib/fusb.cc
+++ b/usrp/host/lib/fusb.cc
@@ -31,7 +31,7 @@
 //                          device handle
 // ------------------------------------------------------------------------
 
-fusb_devhandle::fusb_devhandle (usb_dev_handle *udh)
+fusb_devhandle::fusb_devhandle (libusb_device_handle *udh)
   : d_udh (udh)
 {
   // that's it
diff --git a/usrp/host/lib/fusb.h b/usrp/host/lib/fusb.h
index 769e51c..bfe34d5 100644
--- a/usrp/host/lib/fusb.h
+++ b/usrp/host/lib/fusb.h
@@ -26,7 +26,7 @@
 #define _FUSB_H_
 
 
-struct  usb_dev_handle;
+struct  libusb_device_handle;
 class   fusb_ephandle;
 
 /*!
@@ -39,11 +39,11 @@ private:
   fusb_devhandle &operator= (const fusb_devhandle &rhs);  // no assignment 
operator
 
 protected:
-  usb_dev_handle               *d_udh;
+  libusb_device_handle         *d_udh;
 
 public:
   // CREATORS
-  fusb_devhandle (usb_dev_handle *udh);
+  fusb_devhandle (libusb_device_handle *udh);
   virtual ~fusb_devhandle ();
 
   // MANIPULATORS
@@ -55,7 +55,7 @@ public:
                                        int block_size = 0, int nblocks = 0) = 
0;
   
   // ACCESSORS
-  usb_dev_handle *get_usb_dev_handle () const { return d_udh; }
+  libusb_device_handle *get_libusb_device_handle () const { return d_udh; }
 };
 
 
@@ -116,7 +116,7 @@ public:
   /*!
    * \brief returns fusb_devhandle or throws if trouble
    */
-  static fusb_devhandle *make_devhandle (usb_dev_handle *udh);
+  static fusb_devhandle *make_devhandle (libusb_device_handle *udh);
 
   /*!
    * \brief Returns max block size in bytes (hard limit).
diff --git a/usrp/host/lib/fusb_libusb1.cc b/usrp/host/lib/fusb_libusb1.cc
new file mode 100644
index 0000000..07e05c2
--- /dev/null
+++ b/usrp/host/lib/fusb_libusb1.cc
@@ -0,0 +1,679 @@
+/* -*- 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <fusb_libusb1.h>
+#include <libusb-1.0/libusb.h>
+#include <stdexcept>
+#include <cstdio>
+#include <assert.h>
+#include <string.h>
+#include <algorithm>
+#include <errno.h>
+#include <string.h>
+
+#define MINIMIZE_TX_BUFFERING true 
+
+static const int MAX_BLOCK_SIZE = fusb_sysconfig::max_block_size(); 
+static const int DEFAULT_BLOCK_SIZE = MAX_BLOCK_SIZE;
+static const int DEFAULT_BUFFER_SIZE = 4 * (1L << 20);  // 4 MB endpoint
+static const int LIBUSB_TIMEOUT = 0;                   // no timeout
+
+inline static fusb_ephandle_libusb1*
+lut_get_ephandle (libusb_transfer *lut)
+{
+  return (fusb_ephandle_libusb1 *) lut->user_data;
+}
+
+// ------------------------------------------------------------------------
+//     libusb_transfer allocation, deallocation, and callback 
+// ------------------------------------------------------------------------
+
+static void
+free_lut (libusb_transfer *lut)
+{
+
+  // if this was an input transfer, free the buffer
+  if (lut->endpoint & 0x80)
+    delete [] ((unsigned char *) lut->buffer);
+
+  libusb_free_transfer(lut); 
+
+}
+
+/*
+ * The callback means the libusb_transfer is completed whether sent, cancelled,
+ * or failed. Move the libusb_transfer from the pending list to the
+ * completed list. If the cancel is from the destructor then free the 
+ * transfer instead; normally this won't happen since all endpoints should be
+ * destroyed first leaving the pending list empty.
+ */
+
+static void
+generic_callback(struct libusb_transfer *lut)
+{
+
+  // Fish out devhandle from endpoint
+  fusb_devhandle_libusb1* dev_handle = 
+    lut_get_ephandle(lut)->get_fusb_devhandle_libusb1();
+
+  dev_handle->pending_remove(lut);
+
+  if (lut->status == LIBUSB_TRANSFER_CANCELLED && dev_handle->_teardown() == 1)
+  {
+    free_lut (lut);
+    return;
+  }
+  
+  lut_get_ephandle(lut)->completed_list_add(lut);
+
+} 
+
+static libusb_transfer*
+alloc_lut (fusb_ephandle_libusb1 *self, int buffer_length, int endpoint,
+           bool input_p, unsigned char *write_buffer,
+           fusb_devhandle_libusb1 *dh)
+{
+
+  struct libusb_transfer* lut = libusb_alloc_transfer(0);
+
+  endpoint = (endpoint & 0x7f) | (input_p ? 0x80 : 0);
+
+  if (input_p)
+    write_buffer = new unsigned char [buffer_length];
+
+  // We need the base class libusb_device_handle
+  libusb_device_handle *dev_handle = dh->get_libusb_device_handle();
+
+  // Load the libusb_transfer for bulk transfer
+  libusb_fill_bulk_transfer (lut,              // transfer
+                             dev_handle,        // dev_handle 
+                             endpoint,         // endpoint
+                             write_buffer,     // buffer
+                             buffer_length,    // length
+                             generic_callback, // callback 
+                             self,             // user_data
+                             LIBUSB_TIMEOUT);  // timeout
+
+  return lut;
+}
+
+// ------------------------------------------------------------------------
+//                             device handle
+// ------------------------------------------------------------------------
+
+fusb_devhandle_libusb1::fusb_devhandle_libusb1 (libusb_device_handle *udh)
+  : fusb_devhandle (udh), d_teardown (false)
+{
+  // that's it 
+}
+
+fusb_devhandle_libusb1::~fusb_devhandle_libusb1 ()
+{
+  d_teardown = true;
+
+  std::list<libusb_transfer*>::reverse_iterator it;
+
+  // After cancellation the libusb_transfer is still active so delay freeing
+  // transfer until callback occurs. In most cases the pending list should
+  // already be empty by the time this destructor is called.
+
+  for (it = d_pending_rqsts.rbegin (); it != d_pending_rqsts.rend (); it++) {
+    _cancel_lut (*it);
+  }
+
+  // Wait for pending list to empty
+  _wait_for_completion ();
+
+}
+
+fusb_ephandle*
+fusb_devhandle_libusb1::make_ephandle (int endpoint, bool input_p,
+                                      int block_size, int nblocks)
+{
+  return new fusb_ephandle_libusb1 (this, endpoint, input_p,
+                                   block_size, nblocks);
+}
+
+/*
+ * devhandle list manipulators 
+ */
+
+void 
+fusb_devhandle_libusb1::pending_add (libusb_transfer *lut)
+{
+  d_pending_rqsts.push_back (lut);
+}
+
+
+/*
+ * Attempt to cancel all transations associated with eph
+ */
+
+void
+fusb_devhandle_libusb1::_cancel_pending_rqsts (fusb_ephandle_libusb1 *eph)
+{
+  std::list<libusb_transfer*>::reverse_iterator it;
+
+  for (it = d_pending_rqsts.rbegin (); it != d_pending_rqsts.rend (); it++){
+    if (lut_get_ephandle (*it) == eph)
+      _cancel_lut (*it);
+  }
+}
+
+/*
+ * Pull from the pending list
+ */
+
+libusb_transfer *
+fusb_devhandle_libusb1::pending_get ()
+{
+  if (d_pending_rqsts.empty ())
+    return 0;
+
+  libusb_transfer *lut = d_pending_rqsts.front ();
+  d_pending_rqsts.pop_front ();
+  return lut;
+}
+
+/*
+ * Match libusb_tranfer with the pending list and erase 
+ * Return true if found, false otherwise
+ */
+
+bool
+fusb_devhandle_libusb1::pending_remove (libusb_transfer *lut)
+{
+  std::list<libusb_transfer*>::iterator        result;
+  result = find (d_pending_rqsts.begin (), d_pending_rqsts.end (), lut);
+
+  if (result == d_pending_rqsts.end ()) {
+    fprintf (stderr, "fusb::pending_remove: failed to find lut in 
pending_rqsts: %p\n", lut);
+
+    return false;
+  }
+  d_pending_rqsts.erase (result);
+  return true;
+}
+
+/*
+ * Submit the libusb_transfer to libusb
+ * iff successful, the transfer will be placed on the devhandle pending list.
+ */
+
+bool
+fusb_devhandle_libusb1::_submit_lut (libusb_transfer *lut)
+{
+
+  int ret = libusb_submit_transfer (lut);
+  if (ret < 0) {
+    fprintf(stderr, "fusb::_submit_lut %d", ret);
+    return false;
+  }
+
+  pending_add(lut);
+  return true;
+
+}
+
+/*
+ * Attempt to cancel any pending libusb_transfer transactions. 
+ * Return true in the absence of errors, which does not mean that the transfer
+ * is cancelled. Cancellation can be checked after the callback is fired off
+ * by libusb. 
+ */ 
+
+bool
+fusb_devhandle_libusb1::_cancel_lut (libusb_transfer *lut)
+{
+
+  int ret = libusb_cancel_transfer (lut);
+  if (ret < 0) {
+    fprintf (stderr, "fusb::_cancel_lut");
+    return false;
+  }
+  return true;
+
+}
+
+void
+fusb_devhandle_libusb1::_wait_for_completion ()
+{
+
+  int ret;
+  struct timeval tv;
+  tv.tv_sec = 1;
+  tv.tv_usec =  0;
+
+  // The regular libusb_handle_events sets a hardcoded timeout of 2
+  // seconds. Most of these calls should be changed to appropriate block / non-
+  // blocking version using libusb_handle_events_timeout. This was just a test
+  // usage. 
+
+  while (!d_pending_rqsts.empty ()) {
+    if ((ret = libusb_handle_events_timeout(NULL, &tv)) < 0) {
+      fprintf (stderr, "fusb: libusb_handle_events error %d\n", ret);
+      break;
+    }
+  }
+
+}
+
+// ------------------------------------------------------------------------
+//                             endpoint handle
+// ------------------------------------------------------------------------
+
+fusb_ephandle_libusb1::fusb_ephandle_libusb1 (fusb_devhandle_libusb1 *dh,
+                                             int endpoint, bool input_p,
+                                             int block_size, int nblocks)
+  : fusb_ephandle (endpoint, input_p, block_size, nblocks),
+    d_devhandle (dh),
+    d_write_work_in_progress (0), d_write_buffer (0),
+    d_read_work_in_progress (0), d_read_buffer (0), d_read_buffer_end (0)
+{
+
+  if (d_block_size < 0 || d_block_size > MAX_BLOCK_SIZE)
+    throw std::out_of_range ("fusb_ephandle_libusb1: block_size");
+
+  if (d_nblocks < 0)
+    throw std::out_of_range ("fusb_ephandle_libusb1: nblocks");
+
+  if (d_block_size == 0)
+    d_block_size = DEFAULT_BLOCK_SIZE;
+
+  if (d_nblocks == 0)
+    d_nblocks = std::max (1, DEFAULT_BUFFER_SIZE / d_block_size);
+
+  if (!d_input_p)
+    if (!MINIMIZE_TX_BUFFERING)
+      d_write_buffer = new unsigned char [d_block_size];
+
+  if (0)
+    fprintf(stderr, "fusb_ephandle_libusb1::ctor: d_block_size = %d  d_nblocks 
= %d\n",
+      d_block_size, d_nblocks);
+
+  // allocate libusb_transfers 
+  for (int i = 0; i < d_nblocks; i++)
+    d_free_list.push_back (alloc_lut (this, d_block_size, d_endpoint,
+                                      d_input_p, d_write_buffer, d_devhandle));
+}
+
+fusb_ephandle_libusb1::~fusb_ephandle_libusb1 ()
+{
+
+  stop ();
+
+  libusb_transfer *lut;
+
+  while ((lut = free_list_get ()) != 0)
+    free_lut (lut);
+
+  while ((lut = completed_list_get ()) != 0)
+    free_lut (lut);
+
+  if (d_write_work_in_progress)
+    free_lut (d_write_work_in_progress);
+
+  delete [] d_write_buffer;
+
+  if (d_read_work_in_progress)
+    free_lut (d_read_work_in_progress);
+
+}
+
+bool
+fusb_ephandle_libusb1::start ()
+{
+
+  if (d_started)
+    return true;
+
+  d_started = true;
+
+  if (d_input_p) {
+     libusb_transfer *lut;
+
+     int nerrors = 0;
+     while ((lut = free_list_get ()) !=0 && nerrors < d_nblocks) {
+       if (!submit_lut (lut))
+         nerrors++;
+     }
+  }
+
+  return true;
+
+}
+
+/*
+ * Cancel all transfers in progress or pending and return to initial state 
+ */
+
+bool
+fusb_ephandle_libusb1::stop ()
+{
+
+  if (!d_started)
+    return true;
+
+  if (d_write_work_in_progress){
+    free_list_add (d_write_work_in_progress);
+    d_write_work_in_progress = 0;
+  }
+
+  if (d_read_work_in_progress){
+    free_list_add (d_read_work_in_progress);
+    d_read_work_in_progress = 0;
+    d_read_buffer = 0;
+    d_read_buffer_end = 0;
+  }
+
+  d_devhandle->_cancel_pending_rqsts (this);
+
+  // Do work, reap transfers, etc. 
+  if (libusb_handle_events(NULL) < 0) { 
+    perror ("fusb::libusb_handle_events");
+    return false;
+  }
+
+  while (1) {
+    libusb_transfer *lut;
+    while ((lut = completed_list_get ()) != 0)
+      free_list_add (lut);
+
+    if (d_free_list.size () == (unsigned) d_nblocks)
+      break;
+
+    if (libusb_handle_events(NULL) < 0) {
+      perror ("fusb::libusb_handle_events");
+      return false;
+    }
+  }
+
+  d_started = false;
+  return true;
+
+}
+
+// ------------------------------------------------------------------------
+//                     routines for writing    
+// ------------------------------------------------------------------------
+
+#if (MINIMIZE_TX_BUFFERING)
+
+int
+fusb_ephandle_libusb1::write (const void *buffer, int nbytes)
+{
+
+  if (!d_started)      // doesn't matter here, but keeps semantics constant
+    return -1;
+  
+  if (d_input_p)
+    return -1;
+
+  assert(nbytes % 512 == 0);
+
+  unsigned char *src = (unsigned char *) buffer;
+
+  int n = 0;
+  while (n < nbytes){
+
+    struct libusb_transfer *lut = get_write_work_in_progress();
+    if (!lut)
+      return -1;
+    assert(lut->actual_length == 0);
+    int m = std::min(nbytes - n, MAX_BLOCK_SIZE);
+    lut->buffer = src;
+    lut->length = m;
+
+    n += m;
+    src += m;
+   
+    if (!submit_lut(lut))
+      return -1;
+
+    d_write_work_in_progress = 0;
+  }
+
+  return nbytes;
+}
+
+#else
+
+int
+fusb_ephandle_libusb1::write (const void *buffer, int nbytes)
+{
+  if (!d_started)
+    return -1;
+
+  if (d_input_p)
+    return -1;
+
+  unsigned char *src = (unsigned char *) buffer;
+
+  int n = 0;
+  while (n < nbytes){
+
+    libusb_transfer *lut = get_write_work_in_progress ();
+    if (!lut)
+      return -1;
+    unsigned char *dst = (unsigned char *) lut->buffer;
+    int m = std::min (nbytes - n, lut->length - lut->actual_length);
+
+    memcpy (&dst[lut->actual_length], &src[n], m);
+    lut->actual_length += m;
+    n += m;
+
+    if (lut->actual_length == lut->length){
+      if (!submit_lut (lut))
+        return -1;
+      d_write_work_in_progress = 0;
+    }
+  }
+
+  return n;
+}
+
+#endif
+
+struct libusb_transfer *
+fusb_ephandle_libusb1::get_write_work_in_progress ()
+{
+  if (d_write_work_in_progress)
+    return d_write_work_in_progress;
+
+  while (1) {
+
+    reap_complete_writes ();
+
+    struct libusb_transfer *lut = free_list_get ();
+
+    if (lut != 0){
+      assert (lut->actual_length == 0);
+      d_write_work_in_progress = lut;
+      return lut;
+    }
+
+    // Do work, reap transfers, etc. 
+    libusb_handle_events(NULL);
+  }
+}
+
+void
+fusb_ephandle_libusb1::reap_complete_writes ()
+{
+  // take a look at the completed list and xfer to free list after
+  // checking for errors.
+
+  libusb_transfer *lut;
+
+  while ((lut = completed_list_get ()) != 0) {
+
+    // Check for any errors or short writes that were reporetd in the transfer.
+    // libusb1 sets status, actual_length. 
+
+    if (lut->status != LIBUSB_TRANSFER_COMPLETED) { 
+      fprintf (stderr, "fusb: (status %d) \n", lut->status );
+    } 
+    else if (lut->actual_length != lut->length){
+      fprintf (stderr, "fusb: short write xfer: %d != %d\n",
+               lut->actual_length, lut->length);
+    }
+
+    free_list_add (lut);
+  }
+}
+
+void
+fusb_ephandle_libusb1::wait_for_completion ()
+{
+  d_devhandle->_wait_for_completion ();
+}
+
+// ------------------------------------------------------------------------
+//                     routines for reading    
+// ------------------------------------------------------------------------
+
+int
+fusb_ephandle_libusb1::read (void *buffer, int nbytes)
+{
+  if (!d_started)      // doesn't matter here, but keeps semantics constant
+    return -1;
+
+  if (!d_input_p)
+    return -1;
+
+  unsigned char *dst = (unsigned char *) buffer;
+
+  int n = 0;
+  while (n < nbytes) {
+
+    if (d_read_buffer >= d_read_buffer_end)
+      if (!reload_read_buffer ())
+        return -1;
+
+    int m = std::min (nbytes - n, (int) (d_read_buffer_end - d_read_buffer));
+
+    memcpy (&dst[n], d_read_buffer, m);
+    d_read_buffer += m;
+    n += m;
+  }
+
+  return n;
+
+}
+
+bool
+fusb_ephandle_libusb1::reload_read_buffer ()
+{
+  assert (d_read_buffer >= d_read_buffer_end);
+
+  libusb_transfer *lut;
+
+  if (d_read_work_in_progress) {
+    lut = d_read_work_in_progress;
+    d_read_work_in_progress = 0;
+    d_read_buffer = 0;
+    d_read_buffer_end = 0;
+    lut->actual_length = 0;
+    if (!submit_lut (lut))
+      return false;
+  }
+
+  while (1) {
+
+    while ((lut = completed_list_get ()) == 0 ) {
+      if (libusb_handle_events(NULL) < 0) 
+        fprintf (stderr, "fusb: libusb_handle_events\n");
+    }
+
+    if (lut->status != LIBUSB_TRANSFER_COMPLETED) {
+      fprintf (stderr, "fust: (rd status %d) %s\n", lut->status, 
+               strerror (-lut->status));
+      lut->actual_length = 0;
+      free_list_add (lut);
+      return false;
+    }
+
+    d_read_work_in_progress = lut;
+    d_read_buffer = (unsigned char *) lut->buffer;
+    d_read_buffer_end = d_read_buffer + lut->actual_length;
+
+    return true;
+  }
+}
+
+
+/*
+ * ephandle list manipulation  
+ */
+
+
+void
+fusb_ephandle_libusb1::free_list_add (libusb_transfer *lut)
+{
+  assert (lut_get_ephandle (lut) == this);
+  lut->actual_length = 0;
+  d_free_list.push_back (lut);
+}
+
+libusb_transfer *
+fusb_ephandle_libusb1::free_list_get ()
+{
+  if (d_free_list.empty ())
+    return 0;
+
+  libusb_transfer *lut = d_free_list.front ();
+  d_free_list.pop_front ();
+  return lut;
+}
+
+void
+fusb_ephandle_libusb1::completed_list_add (libusb_transfer *lut)
+{
+  assert (lut_get_ephandle (lut) == this);
+  d_completed_list.push_back (lut);
+}
+
+libusb_transfer *
+fusb_ephandle_libusb1::completed_list_get ()
+{
+  if (d_completed_list.empty ())
+    return 0;
+
+  libusb_transfer *lut = d_completed_list.front ();
+  d_completed_list.pop_front ();
+  return lut;
+}
+
+bool
+fusb_ephandle_libusb1::submit_lut (libusb_transfer *lut)
+{
+  if (!d_devhandle->_submit_lut (lut)) {
+    fprintf (stderr, "_submit_lut failed\n");
+    free_list_add (lut);
+    return false;
+  }
+  return true;
+}
diff --git a/usrp/host/lib/fusb_libusb1.h b/usrp/host/lib/fusb_libusb1.h
new file mode 100644
index 0000000..1661b7a
--- /dev/null
+++ b/usrp/host/lib/fusb_libusb1.h
@@ -0,0 +1,127 @@
+/* -*- 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.
+ */
+
+#ifndef _FUSB_LIBUSB1_H_
+#define _FUSB_LIBUSB1_H_
+
+#include <fusb.h>
+#include <list>
+
+struct libusb_transfer;
+class fusb_ephandle_libusb1;
+
+/*!
+ * \brief libusb1 implementation of fusb_devhandle
+ */
+class fusb_devhandle_libusb1 : public fusb_devhandle
+{
+private:
+  std::list<libusb_transfer*>  d_pending_rqsts;
+
+  void pending_add (struct libusb_transfer *lut);
+  struct libusb_transfer * pending_get ();
+
+  bool d_teardown;
+
+public:
+  // CREATORS
+  fusb_devhandle_libusb1 (libusb_device_handle *udh);
+  virtual ~fusb_devhandle_libusb1 ();
+
+  // MANIPULATORS
+  virtual fusb_ephandle *make_ephandle (int endpoint, bool input_p,
+                                       int block_size = 0, int nblocks = 0);
+  // internal use only
+  bool _submit_lut (libusb_transfer *);
+  bool _cancel_lut (libusb_transfer *);
+  void _cancel_pending_rqsts (fusb_ephandle_libusb1 *eph);
+  void _wait_for_completion ();
+
+  // accessors to work from callback context
+  bool pending_remove (struct libusb_transfer *lut);
+  inline bool _teardown() { return d_teardown; }
+
+};
+
+
+/*!
+ * \brief libusb1 implementation of fusb_ephandle
+ */
+class fusb_ephandle_libusb1 : public fusb_ephandle
+{
+private:
+  fusb_devhandle_libusb1        *d_devhandle;
+  std::list<libusb_transfer*>     d_free_list;
+  std::list<libusb_transfer*>     d_completed_list;
+  libusb_transfer                *d_write_work_in_progress;
+  unsigned char                  *d_write_buffer;
+  libusb_transfer                *d_read_work_in_progress;
+  unsigned char                  *d_read_buffer;
+  unsigned char                  *d_read_buffer_end;
+
+  libusb_transfer *get_write_work_in_progress ();
+  void reap_complete_writes ();
+  bool reload_read_buffer ();
+  bool submit_lut (libusb_transfer *lut); 
+ 
+public:
+  // CREATORS
+  fusb_ephandle_libusb1 (fusb_devhandle_libusb1 *dh, int endpoint, bool 
input_p,
+                        int block_size = 0, int nblocks = 0);
+  virtual ~fusb_ephandle_libusb1 ();
+
+  // MANIPULATORS
+
+  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 ();
+
+  void free_list_add (struct libusb_transfer *lut);
+  void completed_list_add (struct libusb_transfer *lut);
+  struct libusb_transfer *free_list_get ();
+  struct libusb_transfer *completed_list_get ();
+
+  // accessor to work from callback context 
+  fusb_devhandle_libusb1* get_fusb_devhandle_libusb1 () const {
+    return d_devhandle;
+  }
+};
+
+#endif /* _FUSB_LINUX1_H_ */
+
diff --git a/usrp/host/lib/fusb_sysconfig_libusb1.cc 
b/usrp/host/lib/fusb_sysconfig_libusb1.cc
new file mode 100644
index 0000000..e0d9458
--- /dev/null
+++ b/usrp/host/lib/fusb_sysconfig_libusb1.cc
@@ -0,0 +1,49 @@
+/* -*- 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.
+ */
+
+#include <fusb.h>
+#include <fusb_libusb1.h>
+
+static const int MAX_BLOCK_SIZE = 16 * 1024;           // hard limit
+static const int DEFAULT_BLOCK_SIZE =   4 * 1024;
+static const int FUSB_BUFFER_SIZE = 2 * (1L << 20);    // 2 MB
+
+fusb_devhandle *
+fusb_sysconfig::make_devhandle (libusb_device_handle *udh)
+{
+  return new fusb_devhandle_libusb1 (udh);
+}
+       
+int fusb_sysconfig::max_block_size ()
+{
+  return MAX_BLOCK_SIZE;
+}
+
+int fusb_sysconfig::default_block_size ()
+{
+  return DEFAULT_BLOCK_SIZE;
+}
+
+int fusb_sysconfig::default_buffer_size ()
+{
+  return FUSB_BUFFER_SIZE;
+}
-- 
1.6.2.5