Rewrite terminal overlay

2012-01-10 18:49:14 -05:00
parent ba6da2f96e
commit 1a433305f8
5 changed files with 421 additions and 186 deletions
@@ -63,6 +63,13 @@ namespace Terminal {
    }

    wchar_t debug_contents( void ) const;
+
+    bool is_blank( void ) const
+    {
+      return ( contents.empty()
+	       || ( (contents.size() == 1) && ( (contents.front() == 0x20)
+						|| (contents.front() == 0xA0) ) ) );
+    }
  };

  class Row {
@@ -8,7 +8,16 @@

 using namespace Overlay;

-void ConditionalOverlayCell::apply( Framebuffer &fb, bool show_tentative, int row, bool flag ) const
+bool ConditionalOverlay::start_clock( uint64_t local_frame_acked, uint64_t now )
+{
+  if ( (local_frame_acked >= expiration_frame) && (expiration_time == uint64_t(-1)) ) {
+    expiration_time = now + 25;
+    return true;
+  }
+  return false;
+}
+
+void ConditionalOverlayCell::apply( Framebuffer &fb, uint64_t confirmed_epoch, int row, bool flag ) const
 {
  if ( (!active)
       || (row >= fb.ds.get_height())
@@ -16,7 +25,12 @@ void ConditionalOverlayCell::apply( Framebuffer &fb, bool show_tentative, int ro
    return;
  }

-  if ( tentative && (!show_tentative) ) {
+  if ( tentative( confirmed_epoch ) ) {
+    return;
+  }
+
+  if ( unknown ) {
+    fb.get_mutable_cell( row, col )->contents.clear();
    return;
  }

@@ -37,7 +51,7 @@ void ConditionalOverlayCell::apply( Framebuffer &fb, bool show_tentative, int ro
  }
 }

-Validity ConditionalOverlayCell::get_validity( const Framebuffer &fb, int row, uint64_t current_frame ) const
+Validity ConditionalOverlayCell::get_validity( const Framebuffer &fb, int row, uint64_t current_frame, uint64_t now ) const
 {
  if ( !active ) {
    return Inactive;
@@ -51,44 +65,58 @@ Validity ConditionalOverlayCell::get_validity( const Framebuffer &fb, int row, u
  const Cell &current = *( fb.get_cell( row, col ) );

  /* see if it hasn't been updated yet */
-  if ( (current_frame < expiration_frame) ) {
+  if ( current_frame < expiration_frame ) {
+    return Pending;
+  }
+
+  assert( expiration_time != uint64_t(-1) );
+
+  if ( now < expiration_time ) {
    return Pending;
  }

  /* special case deletion */
-  if ( replacement.contents.empty() && (current.contents.size() == 1) && (current.contents.front() == 0x20) ) {
-    return Correct;
+  if ( current.is_blank() && replacement.is_blank() ) {
+    return CorrectNoCredit;
  }

-  if ( replacement.contents.empty() && current.contents.empty() ) {
-    return Correct;
+  if ( unknown ) {
+    return CorrectNoCredit;
  }

-  if ( current == replacement ) {
+  if ( current.contents == replacement.contents ) {
    return Correct;
  } else {
    return IncorrectOrExpired;
  }
 }

-Validity ConditionalCursorMove::get_validity( const Framebuffer &fb, uint64_t current_frame ) const
+Validity ConditionalCursorMove::get_validity( const Framebuffer &fb, uint64_t current_frame, uint64_t now ) const
 {
  if ( !active ) {
-    assert( !show_frozen_cursor );
    return Inactive;
  }

  if ( (row >= fb.ds.get_height())
       || (col >= fb.ds.get_width()) ) {
+    assert( false );
    //    fprintf( stderr, "Crazy cursor (%d,%d)!\n", row, col );
    return IncorrectOrExpired;
  }

+  if ( current_frame < expiration_frame ) {
+    return Pending;
+  }
+
+  assert( expiration_time != uint64_t(-1) );
+
+  if ( now < expiration_time ) {
+    return Pending;
+  }
+
  if ( (fb.ds.get_cursor_col() == col)
       && (fb.ds.get_cursor_row() == row) ) {
    return Correct;
-  } else if ( current_frame < expiration_frame ) {
-    return Pending;
  } else {
    /*
    fprintf( stderr, "Bad cursor in %d (I thought (%d,%d) vs actual (%d,%d)).\n", (int)current_frame,
@@ -98,26 +126,22 @@ Validity ConditionalCursorMove::get_validity( const Framebuffer &fb, uint64_t cu
  }
 }

-void ConditionalCursorMove::apply( Framebuffer &fb ) const
+void ConditionalCursorMove::apply( Framebuffer &fb, uint64_t confirmed_epoch ) const
 {
  if ( !active ) {
    return;
  }

-  int target_row = row;
-  int target_col = col;
-
-  if ( show_frozen_cursor ) {
-    target_row = frozen_row;
-    target_col = frozen_col;
+  if ( tentative( confirmed_epoch ) ) {
+    return;
  }

-  assert( target_row < fb.ds.get_height() );
-  assert( target_col < fb.ds.get_width() );
+  assert( row < fb.ds.get_height() );
+  assert( col < fb.ds.get_width() );
  assert( !fb.ds.origin_mode );

-  fb.ds.move_row( target_row, false );
-  fb.ds.move_col( target_col, false, false );
+  fb.ds.move_row( row, false );
+  fb.ds.move_col( col, false, false );
 }

 NotificationEngine::NotificationEngine()
@@ -242,16 +266,22 @@ int OverlayManager::wait_time( void )
 {
  uint64_t next_expiry = INT_MAX;

-  uint64_t message_delay = notifications.get_message_expiration() - timestamp();
+  uint64_t now = timestamp();
+
+  uint64_t message_delay = notifications.get_message_expiration() - now;

  if ( message_delay < next_expiry ) {
    next_expiry = message_delay;
  }

-  if ( notifications.need_countup( timestamp() ) && ( next_expiry > 1000 ) ) {
+  if ( notifications.need_countup( now ) && ( next_expiry > 1000 ) ) {
    next_expiry = 1000;
  }

+  if ( predictions.active() && ( next_expiry > 10 ) ) {
+    next_expiry = 10;
+  }
+
  return next_expiry;
 }

@@ -260,47 +290,66 @@ void TitleEngine::set_prefix( const wstring s )
  prefix = deque<wchar_t>( s.begin(), s.end() );
 }

-void ConditionalOverlayRow::apply( Framebuffer &fb, bool show_tentative, bool flag ) const
+void ConditionalOverlayRow::apply( Framebuffer &fb, uint64_t confirmed_epoch, bool flag ) const
 {
-  for_each( overlay_cells.begin(), overlay_cells.end(), [&]( const ConditionalOverlayCell &x ) { x.apply( fb, show_tentative, row_num, flag ); } );
+  for_each( overlay_cells.begin(), overlay_cells.end(), [&]( const ConditionalOverlayCell &x ) { x.apply( fb, confirmed_epoch, row_num, flag ); } );
 }

 void PredictionEngine::apply( Framebuffer &fb ) const
 {
-  if ( (score > 0) || cursor.show_frozen_cursor ) {
-    cursor.apply( fb );
+  for_each( cursors.begin(), cursors.end(), [&]( const ConditionalCursorMove &x ) { x.apply( fb, confirmed_epoch ); } );
+
+  for_each( overlays.begin(), overlays.end(), [&]( const ConditionalOverlayRow &x ){ x.apply( fb, confirmed_epoch, flagging ); } );
+}
+
+void PredictionEngine::kill_epoch( uint64_t epoch, const Framebuffer &fb )
+{
+  cursors.remove_if( [&]( ConditionalCursorMove &x ) { return x.tentative( epoch - 1 ); } );
+
+  cursors.push_back( ConditionalCursorMove( local_frame_sent + 1,
+					    fb.ds.get_cursor_row(),
+					    fb.ds.get_cursor_col(),
+					    prediction_epoch ) );
+  cursor().active = true;
+
+  for ( auto i = overlays.begin(); i != overlays.end(); i++ ) {
+    for ( auto j = i->overlay_cells.begin(); j != i->overlay_cells.end(); j++ ) {
+      if ( j->tentative( epoch - 1 ) ) {
+	j->reset();
      }
-  for_each( overlays.begin(), overlays.end(), [&]( const ConditionalOverlayRow &x ){ x.apply( fb, score > 0, flagging ); } );
+    }
+  }
+
+  become_tentative();
 }

 void PredictionEngine::reset( void )
 {
+  cursors.clear();
  overlays.clear();
-  cursor.reset();
  become_tentative();
+
+  //  fprintf( stderr, "RESETTING\n" );
+}
+
+void PredictionEngine::init_cursor( const Framebuffer &fb )
+{
+  if ( cursors.empty() ) {
+    /* initialize new cursor prediction */
+    
+    cursors.push_back( ConditionalCursorMove( local_frame_sent + 1,
+					      fb.ds.get_cursor_row(),
+					      fb.ds.get_cursor_col(),
+					      prediction_epoch ) );
+    cursor().active = true;
+  }
 }

 void PredictionEngine::cull( const Framebuffer &fb )
 {
-  if ( score > 0 ) {
-    cursor.thaw();
-  }
-
  uint64_t now = timestamp();

-  /* don't increment score just for correct cursor position */
-  switch ( cursor.get_validity( fb, local_frame_acked) ) {
-  case IncorrectOrExpired:
-    cursor.reset();
-    become_tentative();
-    return;
-    break;
-  case Correct:
-    cursor.thaw();
-    break;
-  default:
-    break;
-  }
+  /* go through cell predictions */

  uint64_t max_delay = 0;

@@ -314,16 +363,34 @@ void PredictionEngine::cull( const Framebuffer &fb )
      continue;
    }

+    /* smash through "shell prompt" barrier if host has let us */
+    if ( fb.ds.get_cursor_row() == i->row_num ) {
+      if ( i->first_col != INT_MAX ) {
+	if ( fb.ds.get_cursor_col() < i->first_col ) {
+	  i->first_col = 0;
+	}
+      } else {
+	i->first_col = fb.ds.get_cursor_col();
+      }
+    }
+
    for ( auto j = i->overlay_cells.begin(); j != i->overlay_cells.end(); j++ ) {
-      switch ( j->get_validity( fb, i->row_num, local_frame_acked ) ) {
+      if ( j->start_clock( local_frame_acked, now  ) ) {
+	last_scheduled_timeout = max( last_scheduled_timeout, j->expiration_time );
+      }
+      switch ( j->get_validity( fb, i->row_num, local_frame_acked, now ) ) {
      case IncorrectOrExpired:
-	if ( j->tentative ) {
+	if ( j->tentative( confirmed_epoch ) ) {
+
 	  /*
-	  fprintf( stderr, "Bad tentative prediction in row %d, col %d\n",
-		   i->row_num, j->col );
+	  fprintf( stderr, "Bad tentative prediction in row %d, col %d (think %lc, actually %lc)\n",
+		   i->row_num, j->col,
+		   j->replacement.debug_contents(),
+		   fb.get_cell( i->row_num, j->col )->debug_contents()
+		   );
 	  */
-	  j->reset();
-	  become_tentative();
+
+	  kill_epoch( j->tentative_until_epoch, fb );
 	  /*
 	  if ( j->display_time != uint64_t(-1) ) {
 	    fprintf( stderr, "TIMING %ld - %ld (TENT)\n", time(NULL), now - j->display_time );
@@ -331,14 +398,16 @@ void PredictionEngine::cull( const Framebuffer &fb )
 	  */
 	} else {
 	  /*
-	  fprintf( stderr, "[%d=>%d] (score=%d) Killing prediction in row %d, col %d\n",
+	  fprintf( stderr, "[%d=>%d] Killing prediction in row %d, col %d (think %lc, actually %lc)\n",
 		   (int)local_frame_acked, (int)j->expiration_frame,
-		   score,
-		   i->row_num, j->col );
+		   i->row_num, j->col,
+		   j->replacement.debug_contents(),
+		   fb.get_cell( i->row_num, j->col )->debug_contents() );
 	  if ( j->display_time != uint64_t(-1) ) {
 	    fprintf( stderr, "TIMING %ld - %ld\n", time(NULL), now - j->display_time );
 	  }
 	  */
+
 	  reset();
 	  return;
 	}
@@ -350,15 +419,31 @@ void PredictionEngine::cull( const Framebuffer &fb )
 	}
 	*/

-	if ( j->prediction_time > prediction_checkpoint ) {
-	  score++;
+	if ( j->tentative_until_epoch > confirmed_epoch ) {
+	  confirmed_epoch = j->tentative_until_epoch;
+	  /*
+	  fprintf( stderr, "Confirmed epoch %lu (predicting in epoch %lu)\n",
+		   confirmed_epoch, prediction_epoch );
+	  */
+	}
+
+	/* no break */
+      case CorrectNoCredit:
+	if ( i->first_col != INT_MAX ) {
+	  if ( j->col < i->first_col ) {
+	    i->first_col = 0;
+	  }
+	} else {
+	  i->first_col = j->col;
 	}

 	j->reset();

 	break;
      case Pending:
-	max_delay = max( max_delay, now - j->prediction_time );
+	if ( j->display_time != uint64_t(-1) ) {
+	  max_delay = max( max_delay, now - j->display_time );
+	}
 	break;
      default:
 	break;
@@ -373,6 +458,30 @@ void PredictionEngine::cull( const Framebuffer &fb )
  } else if ( max_delay < 50 ) {
    flagging = false;
  }
+
+  /* go through cursor predictions */
+  for ( auto it = cursors.begin(); it != cursors.end(); it++ ) {
+    if ( it->start_clock( local_frame_acked, now ) ) {
+      last_scheduled_timeout = max( last_scheduled_timeout, it->expiration_time );    }
+  }
+
+  if ( !cursors.empty() ) {
+    if ( cursor().get_validity( fb, local_frame_acked, now ) == IncorrectOrExpired ) {
+      /*
+      fprintf( stderr, "Sadly, we're predicting (%d,%d) vs. (%d,%d) [tau: %ld, expiration_time=%ld, now=%ld]\n",
+	       cursor().row, cursor().col,
+	       fb.ds.get_cursor_row(),
+	       fb.ds.get_cursor_col(),
+	       cursor().tentative_until_epoch,
+	       cursor().expiration_time,
+	       now );
+      */
+      reset();
+      return;
+    }
+  }
+
+  cursors.remove_if( [&]( ConditionalCursorMove &x ) { return (x.get_validity( fb, local_frame_acked, now ) != Pending); } );
 }

 ConditionalOverlayRow & PredictionEngine::get_or_make_row( int row_num, int num_cols )
@@ -387,7 +496,7 @@ ConditionalOverlayRow & PredictionEngine::get_or_make_row( int row_num, int num_
    ConditionalOverlayRow r( row_num );
    r.overlay_cells.reserve( num_cols );
    for ( int i = 0; i < num_cols; i++ ) {
-      r.overlay_cells.push_back( ConditionalOverlayCell( i ) );
+      r.overlay_cells.push_back( ConditionalOverlayCell( 0, i, prediction_epoch ) );
      assert( r.overlay_cells[ i ].col == i );
    }
    overlays.push_back( r );
@@ -397,130 +506,222 @@ ConditionalOverlayRow & PredictionEngine::get_or_make_row( int row_num, int num_

 void PredictionEngine::new_user_byte( char the_byte, const Framebuffer &fb )
 {
-  list<Parser::Action *> actions( parser.input( the_byte ) );
+  cull( fb );

-  uint64_t now = timestamp();
+  init_cursor( fb );
+
+  assert( !cursors.empty() );
+
+  /* translate application-mode cursor control function to ANSI cursor control sequence */
+  if ( (last_byte == 0x1b)
+       && (the_byte == 'O') ) {
+    the_byte = '[';
+  }
+  last_byte = the_byte;
+
+  list<Parser::Action *> actions( parser.input( the_byte ) );

  for ( auto it = actions.begin(); it != actions.end(); it++ ) {
    Parser::Action *act = *it;

-    if ( !cursor.active ) {
-      /* initialize new cursor prediction */
-      cursor.row = fb.ds.get_cursor_row();
-      cursor.col = fb.ds.get_cursor_col();
-      cursor.active = true;
-      cursor.prediction_time = now;
-      cursor.expiration_frame = local_frame_sent + 1;
-      assert( !cursor.show_frozen_cursor );
-    }
+    /*
+    fprintf( stderr, "Action: %s (%lc)\n",
+	     act->name().c_str(), act->char_present ? act->ch : L'_' );
+    */

    if ( typeid( *act ) == typeid( Parser::Print ) ) {
      /* make new prediction */

+      assert( act->char_present );
+
      wchar_t ch = act->ch;
      /* XXX handle wide characters */

      if ( ch == 0x7f ) { /* backspace */
 	//	fprintf( stderr, "Backspace.\n" );
-	if ( cursor.col > 0 ) {
-	  cursor.col--;
-
-	  cursor.prediction_time = now;
-	  cursor.expiration_frame = local_frame_sent + 1;
-
-	  ConditionalOverlayCell &cell = get_or_make_row( cursor.row, fb.ds.get_width() ).overlay_cells[ cursor.col ];
-	  cell.active = true;
-	  cell.tentative = (score <= 0);
-	  cell.prediction_time = now;
-	  cell.expiration_frame = local_frame_sent + 1;
-	  cell.replacement.renditions = fb.ds.get_renditions();
-	  cell.replacement.contents.clear();
-	  cell.display_time = -1;
+	ConditionalOverlayRow &the_row = get_or_make_row( cursor().row, fb.ds.get_width() );
+	if ( cursor().col <= the_row.first_col ) {
+	  become_tentative();
 	}
-      } else if ( (ch < 0x20) || (ch > 0x7E) ) {
+
+	if ( cursor().col > 0 ) {
+	  cursor().col--;
+	  cursor().expire( local_frame_sent + 1 );
+
+	  for ( int i = cursor().col; i < fb.ds.get_width(); i++ ) {
+	    ConditionalOverlayCell &cell = the_row.overlay_cells[ i ];
+	    cell.reset();
+	    cell.active = true;
+	    cell.tentative_until_epoch = prediction_epoch;
+	    cell.expire( local_frame_sent + 1 );
+	  
+	    if ( i + 2 < fb.ds.get_width() ) {
+	      ConditionalOverlayCell &next_cell = the_row.overlay_cells[ i + 1 ];
+	      const Cell *next_cell_actual = fb.get_cell( cursor().row, i + 1 );
+
+	      if ( next_cell.active ) {
+		if ( next_cell.unknown ) {
+		  cell.unknown = true;
+		} else {
+		  cell.unknown = false;
+		  cell.replacement = next_cell.replacement;
+		}
+	      } else {
+		cell.unknown = false;
+		cell.replacement = *next_cell_actual;
+	      }
+	    } else {
+	      cell.unknown = true;
+	    }
+	  }
+	}
+      } else if ( (ch < 0x20) || (wcwidth( ch ) != 1) ) {
 	/* unknown print */
 	become_tentative();
 	//	fprintf( stderr, "Unknown print 0x%x\n", ch );
      } else {
-	/* don't attempt to change existing blank or space cells if user has typed space */
-	const Cell *existing_cell = fb.get_cell( cursor.row, cursor.col );
-	if ( ( existing_cell->contents.empty() || ((existing_cell->contents.size() == 1)
-						   && ( (existing_cell->contents.front() == 0x20)
-							|| (existing_cell->contents.front() == 0xA0) )))
-	     && ( ch == 0x20 ) ) {
-	  /* do nothing */
-	} else {
-	  assert( cursor.row >= 0 );
-	  assert( cursor.col >= 0 );
-	  assert( cursor.row < fb.ds.get_height() );
-	  assert( cursor.col < fb.ds.get_width() );
+	assert( cursor().row >= 0 );
+	assert( cursor().col >= 0 );
+	assert( cursor().row < fb.ds.get_height() );
+	assert( cursor().col < fb.ds.get_width() );

-	  if ( cursor.col + 1 >= fb.ds.get_width() ) {
+	ConditionalOverlayRow &the_row = get_or_make_row( cursor().row, fb.ds.get_width() );
+
+	if ( cursor().col + 1 >= fb.ds.get_width() ) {
 	  /* prediction in the last column is tricky */
 	  /* e.g., emacs will show wrap character, shell will just put the character there */
 	  become_tentative();
-	    cursor.freeze();
 	}

-	  ConditionalOverlayCell &cell = get_or_make_row( cursor.row, fb.ds.get_width() ).overlay_cells[ cursor.col ];
+	/* do the insert */
+	for ( int i = fb.ds.get_width() - 1; i > cursor().col; i-- ) {
+	  ConditionalOverlayCell &cell = the_row.overlay_cells[ i ];
+	  cell.reset();
 	  cell.active = true;
-	  cell.tentative = (score <= 0);
-	  cell.prediction_time = now;
-	  cell.expiration_frame = local_frame_sent + 1;
+	  cell.tentative_until_epoch = prediction_epoch;
+	  cell.expire( local_frame_sent + 1 );
+
+	  ConditionalOverlayCell &prev_cell = the_row.overlay_cells[ i - 1 ];
+	  const Cell *prev_cell_actual = fb.get_cell( cursor().row, i - 1 );
+
+	  if ( i == fb.ds.get_width() - 1 ) {
+	    cell.unknown = true;
+	  } else if ( prev_cell.active ) {
+	    if ( prev_cell.unknown ) {
+	      cell.unknown = true;
+	    } else {
+	      cell.unknown = false;
+	      cell.replacement = prev_cell.replacement;
+	    }
+	  } else {
+	    cell.unknown = false;
+	    cell.replacement = *prev_cell_actual;
+	  }
+	}
+	
+	ConditionalOverlayCell &cell = the_row.overlay_cells[ cursor().col ];
+	cell.reset();
+	cell.active = true;
+	cell.tentative_until_epoch = prediction_epoch;
+	cell.expire( local_frame_sent + 1 );
 	cell.replacement.renditions = fb.ds.get_renditions();
 	cell.replacement.contents.clear();
 	cell.replacement.contents.push_back( ch );
-	  cell.display_time = -1;

 	/*
-	  fprintf( stderr, "[%d=>%d] Predicting %lc in row %d, col %d\n",
+	fprintf( stderr, "[%d=>%d] Predicting %lc in row %d, col %d [tue: %lu]\n",
 		 (int)local_frame_acked, (int)cell.expiration_frame,
-		   ch, cursor.row, cursor.col );
+		 ch, cursor().row, cursor().col,
+		 cell.tentative_until_epoch );
 	*/
-	}

-	cursor.prediction_time = now;
-	cursor.expiration_frame = local_frame_sent + 1;
-	cursor.col++;
+	cursor().expire( local_frame_sent + 1 );
+	cursor().col++;

 	/* do we need to wrap? */
-	if ( cursor.col >= fb.ds.get_width() ) {
-	  become_tentative();
-	  cursor.col--;
-	  cursor.freeze();
-	  cursor.col = 0;
-	  if ( cursor.row == fb.ds.get_height() - 1 ) {
-	    for ( auto i = overlays.begin(); i != overlays.end(); i++ ) {
-	      i->row_num--;
-	      for ( auto j = i->overlay_cells.begin(); j != i->overlay_cells.end(); j++ ) {
-		if ( j->active ) {
-		  //		  j->tentative = (score <= 0);
-		  j->prediction_time = now;
-		  j->expiration_frame = local_frame_sent + 1;
-		}
-	      }
-	    }
-	  } else {
-	    cursor.row++;
-	  }
+	if ( cursor().col >= fb.ds.get_width() ) {
+	  newline_carriage_return( fb );
 	}
      }
    } else if ( typeid( *act ) == typeid( Parser::Execute ) ) {
+      if ( act->char_present && (act->ch == 0x0d) /* CR */ ) {
 	become_tentative();
-      cursor.freeze();
+	newline_carriage_return( fb );
+      } else {
 	//	fprintf( stderr, "Execute 0x%x\n", act->ch );
+	become_tentative();	
+      }
    } else if ( typeid( *act ) == typeid( Parser::Esc_Dispatch ) ) {
      //      fprintf( stderr, "Escape sequence\n" );
+      become_tentative();
    } else if ( typeid( *act ) == typeid( Parser::CSI_Dispatch ) ) {
-      //      fprintf( stderr, "CSI sequence\n" );
+      if ( act->char_present && (act->ch == L'C') ) { /* right arrow */
+	if ( cursor().col < fb.ds.get_width() - 1 ) {
+	  cursor().col++;
+	  cursor().expire( local_frame_sent + 1 );
+	}
+      } else if ( act->char_present && (act->ch == L'D') ) { /* left arrow */
+	ConditionalOverlayRow &the_row = get_or_make_row( cursor().row, fb.ds.get_width() );
+	if ( cursor().col <= the_row.first_col ) {
+	  become_tentative();	    
+	}
+	
+	if ( cursor().col > 0 ) {
+	  cursor().col--;
+	  cursor().expire( local_frame_sent + 1 );
+	}
+      } else {
+	//	fprintf( stderr, "CSI sequence %lc\n", act->ch );
+	become_tentative();
+      }
+    } else if ( typeid( *act ) == typeid( Parser::Clear ) ) {
+
    }

    delete act;
  }
 }

+void PredictionEngine::newline_carriage_return( const Framebuffer &fb )
+{
+  cursor().col = 0;
+  if ( cursor().row == fb.ds.get_height() - 1 ) {
+    for ( auto i = overlays.begin(); i != overlays.end(); i++ ) {
+      i->row_num--;
+      for ( auto j = i->overlay_cells.begin(); j != i->overlay_cells.end(); j++ ) {
+	if ( j->active ) {
+	  j->expire( local_frame_sent + 1 );
+	}
+      }
+    }
+
+    /* make blank prediction for last row */
+    ConditionalOverlayRow &the_row = get_or_make_row( cursor().row, fb.ds.get_width() );
+    for ( auto j = the_row.overlay_cells.begin(); j != the_row.overlay_cells.end(); j++ ) {
+      j->active = true;
+      j->tentative_until_epoch = prediction_epoch;
+      j->expire( local_frame_sent + 1 );
+      j->replacement.contents.clear();
+    }
+  } else {
+    cursor().row++;
+  }
+}
+
 void PredictionEngine::become_tentative( void )
 {
-  prediction_checkpoint = timestamp();
-  score = 0;
+  prediction_epoch++;
+
+  if ( !cursors.empty() ) {
+    cursors.push_back( ConditionalCursorMove( local_frame_sent + 1,
+					      cursor().row,
+					      cursor().col,
+					      prediction_epoch ) );
+    cursor().active = true;
+  }
+
+  /*
+  fprintf( stderr, "Now tentative in epoch %lu (confirmed=%lu)\n",
+	   prediction_epoch, confirmed_epoch );
+  */
 }
@@ -15,75 +15,76 @@ namespace Overlay {
  enum Validity {
    Pending,
    Correct,
+    CorrectNoCredit,
    IncorrectOrExpired,
    Inactive
  };

  class ConditionalOverlay {
  public:
-    uint64_t prediction_time, expiration_frame;
+    uint64_t expiration_frame;
+    uint64_t expiration_time; /* after frame is hit */
    int col;
    bool active; /* represents a prediction at all */
-    bool tentative; /* whether to hide when score < 0 */
+    uint64_t tentative_until_epoch; /* when to show */

-    ConditionalOverlay( uint64_t s_exp, int s_col )
-      : prediction_time( timestamp() ),
-	expiration_frame( s_exp ), col( s_col ),
+    ConditionalOverlay( uint64_t s_exp, int s_col, uint64_t s_tentative )
+      : expiration_frame( s_exp ), expiration_time( -1 ), col( s_col ),
 	active( false ),
-	tentative( false )
+	tentative_until_epoch( s_tentative )
    {}

    virtual ~ConditionalOverlay() {}
+
+    bool tentative( uint64_t confirmed_epoch ) const { return tentative_until_epoch > confirmed_epoch; }
+    void reset( void ) { expiration_frame = expiration_time = tentative_until_epoch = -1; active = false; }
+    bool start_clock( uint64_t local_frame_acked, uint64_t now );
+    void expire( uint64_t s_exp ) { expiration_frame = s_exp; expiration_time = uint64_t(-1); }
  };

  class ConditionalCursorMove : public ConditionalOverlay {
  public:
    int row;

-    int frozen_col, frozen_row; /* after a control character */
+    void apply( Framebuffer &fb, uint64_t confirmed_epoch ) const;

-    bool show_frozen_cursor;
+    Validity get_validity( const Framebuffer &fb, uint64_t current_frame, uint64_t now ) const;

-    void apply( Framebuffer &fb ) const;
-
-    Validity get_validity( const Framebuffer &fb, uint64_t current_frame ) const;
-
-    ConditionalCursorMove( uint64_t s_exp, int s_row, int s_col )
-      : ConditionalOverlay( s_exp, s_col ), row( s_row ), frozen_col( 0 ), frozen_row( 0 ),
-	show_frozen_cursor( false )
+    ConditionalCursorMove( uint64_t s_exp, int s_row, int s_col, uint64_t s_tentative )
+      : ConditionalOverlay( s_exp, s_col, s_tentative ), row( s_row )
    {}
-
-    void freeze( void ) { frozen_col = col; frozen_row = row; show_frozen_cursor = true; }
-    void thaw( void ) { show_frozen_cursor = false; }
-    void reset( void ) { active = false; thaw(); }
  };

  class ConditionalOverlayCell : public ConditionalOverlay {
  public:
    Cell replacement;
+    bool unknown;

    mutable uint64_t display_time;

-    void apply( Framebuffer &fb, bool show_tentative, int row, bool flag ) const;
-    Validity get_validity( const Framebuffer &fb, int row, uint64_t current_frame ) const;
+    void apply( Framebuffer &fb, uint64_t confirmed_epoch, int row, bool flag ) const;
+    Validity get_validity( const Framebuffer &fb, int row, uint64_t current_frame, uint64_t now ) const;

-    ConditionalOverlayCell( int s_col )
-      : ConditionalOverlay( 0, s_col ),
+    ConditionalOverlayCell( uint64_t s_exp, int s_col, uint64_t s_tentative )
+      : ConditionalOverlay( s_exp, s_col, s_tentative ),
 	replacement( 0 ),
+	unknown( false ),
 	display_time( -1 )
    {}

-    void reset( void ) { active = false; display_time = -1; }
+    void reset( void ) { unknown = false; display_time = -1; ConditionalOverlay::reset(); }
  };

  class ConditionalOverlayRow {
  public:
    int row_num;
+    int first_col;
+
    vector<ConditionalOverlayCell> overlay_cells;

-    void apply( Framebuffer &fb, bool show_tentative, bool flag ) const;
+    void apply( Framebuffer &fb, uint64_t confirmed_epoch, bool flag ) const;

-    ConditionalOverlayRow( int s_row_num ) : row_num( s_row_num ), overlay_cells() {}
+    ConditionalOverlayRow( int s_row_num ) : row_num( s_row_num ), first_col( INT_MAX ), overlay_cells() {}
  };

  /* the various overlays */
@@ -107,24 +108,34 @@ namespace Overlay {

  class PredictionEngine {
  private:
+    char last_byte;
    Parser::UTF8Parser parser;

    list<ConditionalOverlayRow> overlays;

-    ConditionalCursorMove cursor;
-
-    int score;
+    list<ConditionalCursorMove> cursors;

    uint64_t local_frame_sent, local_frame_acked;

    ConditionalOverlayRow & get_or_make_row( int row_num, int num_cols );

-    uint64_t prediction_checkpoint;
+    uint64_t prediction_epoch;
+    uint64_t confirmed_epoch;

    void become_tentative( void );

+    void newline_carriage_return( const Framebuffer &fb );
+
    bool flagging;

+    ConditionalCursorMove & cursor( void ) { return cursors.back(); }
+
+    void kill_epoch( uint64_t epoch, const Framebuffer &fb );
+
+    void init_cursor( const Framebuffer &fb );
+
+    uint64_t last_scheduled_timeout;
+
  public:
    void apply( Framebuffer &fb ) const;
    void new_user_byte( char the_byte, const Framebuffer &fb );
@@ -132,14 +143,16 @@ namespace Overlay {

    void reset( void );

+    bool active( void ) { return timestamp() <= last_scheduled_timeout; }
+
    void set_local_frame_sent( uint64_t x ) { local_frame_sent = x; }
    void set_local_frame_acked( uint64_t x ) { local_frame_acked = x; }

-    PredictionEngine( void ) : parser(), overlays(), cursor( 0, 0, 0 ), score( 0 ),
+    PredictionEngine( void ) : last_byte( 0 ), parser(), overlays(), cursors(),
 			       local_frame_sent( 0 ), local_frame_acked( 0 ),
-			       prediction_checkpoint( timestamp() ), flagging( false )
+			       prediction_epoch( 0 ), confirmed_epoch( 0 ),
+			       flagging( false ), last_scheduled_timeout( 0 )
    {
-      become_tentative();
    }
  };

@@ -20,6 +20,7 @@ TransportSender<MyState>::TransportSender( Connection *s_connection, MyState &in
    shutdown_tries( 0 ),
    ack_num( 0 ),
    pending_data_ack( false ),
+    ack_timestamp( 0 ),
    SEND_MINDELAY( 15 )
 {
 }
@@ -218,6 +219,9 @@ template <class MyState>
 void TransportSender<MyState>::send_in_fragments( string diff, uint64_t new_num )
 {
  Instruction inst;
+
+  uint64_t now = timestamp();
+
  inst.set_protocol_version( MOSH_PROTOCOL_VERSION );
  inst.set_old_num( assumed_receiver_state->num );
  inst.set_new_num( new_num );
@@ -235,11 +239,12 @@ void TransportSender<MyState>::send_in_fragments( string diff, uint64_t new_num
    connection->send( i->tostring() );

    if ( verbose ) {
-      fprintf( stderr, "[%u] Sent [%d=>%d] id %d, frag %d ack=%d, throwaway=%d, len=%d, frame rate=%.2f, timeout=%d, srtt=%.1f\n",
+      fprintf( stderr, "[%u] Sent [%d=>%d] id %d, frag %d ack=%d, throwaway=%d, len=%d, frame rate=%.2f, timeout=%d, srtt=%.1f age=%lu\n",
 	       (unsigned int)(timestamp() % 100000), (int)inst.old_num(), (int)inst.new_num(), (int)i->id, (int)i->fragment_num,
 	       (int)inst.ack_num(), (int)inst.throwaway_num(), (int)i->contents.size(),
 	       1000.0 / (double)send_interval(),
-	       (int)connection->timeout(), connection->get_SRTT() );
+	       (int)connection->timeout(), connection->get_SRTT(),
+	       now - ack_timestamp );
    }

  }
@@ -253,8 +258,8 @@ void TransportSender<MyState>::process_acknowledgment_through( uint64_t ack_num
  /* Ignore ack if we have culled the state it's acknowledging */

  if ( sent_states.end() != find_if( sent_states.begin(), sent_states.end(),
-				     [&]( TimestampedState<MyState> x ) { return x.num == ack_num; } ) ) {
-    sent_states.remove_if( [&]( TimestampedState<MyState> x ) { return x.num < ack_num; } );
+				     [&]( TimestampedState<MyState> &x ) { return x.num == ack_num; } ) ) {
+    sent_states.remove_if( [&]( TimestampedState<MyState> &x ) { return x.num < ack_num; } );
  }

  assert( !sent_states.empty() );
@@ -266,3 +271,11 @@ bool TransportSender<MyState>::shutdown_ack_timed_out( void )
 {
  return shutdown_tries >= SHUTDOWN_RETRIES;
 }
+
+/* Executed upon entry to new receiver state */
+template <class MyState>
+void TransportSender<MyState>::set_ack_num( uint64_t s_ack_num )
+{
+  ack_num = s_ack_num;
+  ack_timestamp = timestamp();
+}
@@ -60,8 +60,9 @@ namespace Network {
    /* information about receiver state */
    uint64_t ack_num;
    bool pending_data_ack;
+    uint64_t ack_timestamp;

-    int SEND_MINDELAY; /* ms to collect all input */
+    unsigned int SEND_MINDELAY; /* ms to collect all input */

  public:
    /* constructor */
@@ -77,7 +78,7 @@ namespace Network {
    void process_acknowledgment_through( uint64_t ack_num );

    /* Executed upon entry to new receiver state */
-    void set_ack_num( uint64_t s_ack_num ) { ack_num = s_ack_num; }
+    void set_ack_num( uint64_t s_ack_num );

    /* Accelerate reply ack */
    void set_data_ack( void ) { pending_data_ack = true; }