Initial revision

src/scroll.c

@@ -0,0 +1,606 @@
+/* Calculate what line insertion or deletion to do, and do it,
+   Copyright (C) 1985, 1986, 1990 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs 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 1, or (at your option)
+any later version.
+
+GNU Emacs 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 Emacs; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+
+#include "config.h"
+#include "termchar.h"
+#include "lisp.h"
+#include "dispextern.h"
+#include "screen.h"
+
+extern struct display_line **ophys_lines;
+
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+/* All costs measured in characters.
+   So no cost can exceed the area of a screen, measured in characters.
+   Let's hope this is never more than 15000 characters.  */
+
+#define INFINITY 15000
+
+struct matrix_elt
+  {
+    /* Cost of outputting through this line
+       if no insert/delete is done just above it.  */
+    short writecost;
+    /* Cost of outputting through this line
+       if an insert is done just above it.  */
+    short insertcost;
+    /* Cost of outputting through this line
+       if a delete is done just above it.  */
+    short deletecost;
+    /* Number of inserts so far in this run of inserts,
+       for the cost in insertcost.  */
+    char insertcount;
+    /* Number of deletes so far in this run of deletes,
+       for the cost in deletecost.  */
+    char deletecount;
+  };
+
+/* See do_line_insertion_deletion_costs for info on these arrays. */
+
+#ifndef MULTI_SCREEN
+static int *insert_line_cost;
+static int *delete_line_cost;
+static int *insert_n_lines_cost;
+static int *delete_n_lines_cost;
+#endif
+
+
+/* Determine, in matrix[i,j], the cost of updating the first j old lines
+   into the first i new lines.
+   This involves using insert or delete somewhere if i != j.
+   For each matrix elements, three kinds of costs are recorded:
+   the smallest cost that ends with an insert, the smallest
+   cost that ends with a delete, and the smallest cost that
+   ends with neither one.  These are kept separate because
+   on some terminals the cost of doing an insert varies
+   depending on whether one was just done, etc.  */
+
+/* draw_cost[VPOS] is the cost of outputting new line at VPOS.
+   old_hash[VPOS] is the hash code of the old line at VPOS.
+   new_hash[VPOS] is the hash code of the new line at VPOS.
+   Note that these are not true screen vpos's, but relative
+   to the place at which the first mismatch between old and
+   new contents appears.  */
+
+static void
+calculate_scrolling (screen, matrix, window_size, lines_below,
+		     draw_cost, old_hash, new_hash,
+		     free_at_end)
+     SCREEN_PTR screen;
+     /* matrix is of size window_size + 1 on each side.  */
+     struct matrix_elt *matrix;
+     int window_size;
+     int *draw_cost;
+     int *old_hash;
+     int *new_hash;
+     int free_at_end;
+{
+  register int i, j;
+  int screen_height = SCREEN_HEIGHT (screen);
+  register struct matrix_elt *p, *p1;
+  register int cost, cost1;
+
+  int lines_moved = window_size + (scroll_region_ok ? 0 : lines_below);
+  /* first_insert_cost[I] is the cost of doing the first insert-line
+     at the I'th line of the lines we are considering,
+     where I is origin 1 (as it is below).  */
+  int *first_insert_cost
+    = &SCREEN_INSERT_COST (screen)[screen_height - 1 - lines_moved];
+  int *first_delete_cost
+    = &SCREEN_DELETE_COST (screen)[screen_height - 1 - lines_moved];
+  int *next_insert_cost
+    = &SCREEN_INSERTN_COST (screen)[screen_height - 1 - lines_moved];
+  int *next_delete_cost
+    = &SCREEN_DELETEN_COST (screen)[screen_height - 1 - lines_moved];
+
+  /* Discourage long scrolls on fast lines.
+     Don't scroll nearly a full screen height unless it saves
+     at least 1/4 second.  */
+  int extra_cost = baud_rate / (10 * 4 * SCREEN_HEIGHT (screen));
+
+  /* initialize the top left corner of the matrix */
+  matrix->writecost = 0;
+  matrix->insertcost = INFINITY;
+  matrix->deletecost = INFINITY;
+  matrix->insertcount = 0;
+  matrix->deletecount = 0;
+
+  /* initialize the left edge of the matrix */
+  cost = first_insert_cost[1] - next_insert_cost[1];
+  for (i = 1; i <= window_size; i++)
+    {
+      p = matrix + i * (window_size + 1);
+      cost += draw_cost[i] + next_insert_cost[i] + extra_cost;
+      p->insertcost = cost;
+      p->writecost = INFINITY;
+      p->deletecost = INFINITY;
+      p->insertcount = i;
+      p->deletecount = 0;
+    }
+
+  /* initialize the top edge of the matrix */
+  cost = first_delete_cost[1] - next_delete_cost[1];
+  for (j = 1; j <= window_size; j++)
+    {
+      cost += next_delete_cost[j];
+      matrix[j].deletecost = cost;
+      matrix[j].writecost = INFINITY;
+      matrix[j].insertcost = INFINITY;
+      matrix[j].deletecount = j;
+      matrix[j].insertcount = 0;
+    }
+
+  /* `i' represents the vpos among new screen contents.
+     `j' represents the vpos among the old screen contents.  */
+  p = matrix + window_size + 2;	/* matrix [1, 1] */
+  for (i = 1; i <= window_size; i++, p++)
+    for (j = 1; j <= window_size; j++, p++)
+      {
+	/* p contains the address of matrix [i, j] */
+
+	/* First calculate the cost assuming we do
+	   not insert or delete above this line.
+	   That is, if we update through line i-1
+	   based on old lines through j-1,
+	   and then just change old line j to new line i.  */
+	p1 = p - window_size - 2; /* matrix [i-1, j-1] */
+	cost = p1->writecost;
+	if (cost > p1->insertcost)
+	  cost = p1->insertcost;
+	if (cost > p1->deletecost)
+	  cost = p1->deletecost;
+	if (old_hash[j] != new_hash[i])
+	  cost += draw_cost[i];
+	p->writecost = cost;
+
+	/* Calculate the cost if we do an insert-line
+	   before outputting this line.
+	   That is, we update through line i-1
+	   based on old lines through j,
+	   do an insert-line on line i,
+	   and then output line i from scratch,
+	   leaving old lines starting from j for reuse below.  */
+	p1 = p - window_size - 1; /* matrix [i-1, j] */
+	/* No need to think about doing a delete followed
+	   immediately by an insert.  It cannot be as good
+	   as not doing either of them.  */
+	if (free_at_end == i)
+	  {
+	    cost = p1->writecost;
+	    cost1 = p1->insertcost;
+	  }
+	else
+	  {
+	    cost = p1->writecost + first_insert_cost[i];
+	    if (p1->insertcount > i)
+	      abort ();
+	    cost1 = p1->insertcost + next_insert_cost[i - p1->insertcount];
+	  }
+	p->insertcost = min (cost, cost1) + draw_cost[i] + extra_cost;
+	p->insertcount = (cost < cost1) ? 1 : p1->insertcount + 1;
+	if (p->insertcount > i)
+	  abort ();
+
+	/* Calculate the cost if we do a delete line after
+	   outputting this line.
+	   That is, we update through line i
+	   based on old lines through j-1,
+	   and throw away old line j.  */
+	p1 = p - 1;		/* matrix [i, j-1] */
+	/* No need to think about doing an insert followed
+	   immediately by a delete.  */
+	if (free_at_end == i)
+	  {
+	    cost = p1->writecost;
+	    cost1 = p1->deletecost;
+	  }
+	else
+	  {
+	    cost = p1->writecost + first_delete_cost[i];
+	    cost1 = p1->deletecost + next_delete_cost[i];
+	  }
+	p->deletecost = min (cost, cost1);
+	p->deletecount = (cost < cost1) ? 1 : p1->deletecount + 1;
+      }
+}
+
+/* Perform insert-lines and delete-lines operations
+ according to the costs in the matrix.
+ Updates the contents of the screen to record what was done. */
+
+static void
+do_scrolling (screen, matrix, window_size, unchanged_at_top)
+     SCREEN_PTR screen;
+     struct matrix_elt *matrix;
+     int window_size;
+     int unchanged_at_top;
+{
+  register struct matrix_elt *p;
+  register int i, j;
+  register struct screen_glyphs *current_screen;
+  register struct screen_glyphs *temp_screen;
+  struct queue { int count, pos; } *queue;
+  int offset = unchanged_at_top;
+  int qi = 0;
+  int window = 0;
+  register int tem;
+  int next;
+
+  queue = (struct queue *) alloca (SCREEN_HEIGHT (screen)
+				   * sizeof (struct queue));
+
+  current_screen = SCREEN_CURRENT_GLYPHS (screen);
+  temp_screen = SCREEN_TEMP_GLYPHS (screen);
+
+  bcopy (current_screen->glyphs, temp_screen->glyphs,
+	 current_screen->height * sizeof (GLYPH *));
+  bcopy (current_screen->used, temp_screen->used,
+	 current_screen->height * sizeof (int));
+  bcopy (current_screen->highlight, temp_screen->highlight,
+	 current_screen->height * sizeof (char));
+  bzero (temp_screen->enable, temp_screen->height * sizeof (char));
+  bcopy (current_screen->bufp, temp_screen->bufp,
+	 current_screen->height * sizeof (int));
+
+#ifdef HAVE_X_WINDOWS
+  if (SCREEN_IS_X (screen))
+    {
+      bcopy (current_screen->nruns, temp_screen->nruns,
+	     current_screen->height * sizeof (int));
+      bcopy (current_screen->face_list, temp_screen->face_list,
+	     current_screen->height * sizeof (struct run *));
+      bcopy (current_screen->top_left_x, temp_screen->top_left_x,
+	     current_screen->height * sizeof (short));
+      bcopy (current_screen->top_left_y, temp_screen->top_left_y,
+	     current_screen->height * sizeof (short));
+      bcopy (current_screen->pix_width, temp_screen->pix_width,
+	     current_screen->height * sizeof (short));
+      bcopy (current_screen->pix_height, temp_screen->pix_height,
+	     current_screen->height * sizeof (short));
+    }
+#endif
+
+  i = j = window_size;
+
+  while (i > 0 || j > 0)
+    {
+      p = matrix + i * (window_size + 1) + j;
+      tem = p->insertcost;
+      if (tem < p->writecost && tem < p->deletecost)
+	{
+	  /* Insert should be done at vpos i-1, plus maybe some before */
+	  queue[qi].count = p->insertcount;
+	  i -= p->insertcount;
+	  queue[qi++].pos = i + unchanged_at_top;
+	}
+      else if (p->deletecost < p->writecost)
+	{
+	  /* Old line at vpos j-1, and maybe some before it,
+	     should be deleted */
+	  j -= p->deletecount;
+ 	  if (!window)
+	    {
+	      set_terminal_window (window_size + unchanged_at_top);
+	      window = 1;
+	    }
+	  ins_del_lines (j + unchanged_at_top, - p->deletecount);
+	}
+      else
+	{
+	  /* Best thing done here is no insert or delete */
+	  /* Old line at vpos j-1 ends up at vpos i-1 */
+	  current_screen->glyphs[i + offset - 1]
+	    = temp_screen->glyphs[j + offset - 1];
+	  current_screen->used[i + offset - 1]
+	    = temp_screen->used[j + offset - 1];
+	  current_screen->highlight[i + offset - 1]
+	    = temp_screen->highlight[j + offset - 1];
+
+	  temp_screen->enable[j + offset - 1] = 1;
+	  i--;
+	  j--;
+	}
+    }
+
+  if (!window && qi)
+    {
+      set_terminal_window (window_size + unchanged_at_top);
+      window = 1;
+    }
+
+  /* Now do all insertions */
+
+  next = unchanged_at_top;
+  for (i = qi - 1; i >= 0; i--)
+    {
+      ins_del_lines (queue[i].pos, queue[i].count);
+
+      /* Mark the inserted lines as clear,
+	 and put into them the line-contents strings
+	 that were discarded during the deletions.
+	 Those are the ones for which temp_screen->enable was not set.  */
+      tem = queue[i].pos;
+      for (j = tem + queue[i].count - 1; j > tem; j--)
+	{
+	  current_screen->enable[j] = 0;
+	  while (temp_screen->enable[next])
+	    next++;
+	  current_screen->glyphs[j] = temp_screen->glyphs[next++];
+	}
+    }
+
+  if (window)
+    set_terminal_window (0);
+}
+
+void
+scrolling_1 (screen, window_size, unchanged_at_top, unchanged_at_bottom,
+	     draw_cost, old_hash, new_hash, free_at_end)
+     SCREEN_PTR screen;
+     int window_size, unchanged_at_top, unchanged_at_bottom;
+     int *draw_cost;
+     int *old_hash;
+     int *new_hash;
+     int free_at_end;
+{
+  struct matrix_elt *matrix;
+  matrix = ((struct matrix_elt *)
+	    alloca ((window_size + 1) * (window_size + 1) * sizeof *matrix));
+
+  calculate_scrolling (screen, matrix, window_size, unchanged_at_bottom,
+		       draw_cost, old_hash, new_hash,
+		       free_at_end);
+  do_scrolling (screen, matrix, window_size, unchanged_at_top);
+}
+
+/* Return number of lines in common between current and desired screen contents
+   described to us only as vectors of hash codes OLDHASH and NEWHASH.
+   Consider only vpos range START to END (not including END).
+   Ignore short lines on the assumption that
+   avoiding redrawing such a line will have little weight.  */
+
+int
+scrolling_max_lines_saved (start, end, oldhash, newhash, cost)
+     int start, end;
+     int *oldhash, *newhash, *cost;
+{
+  struct { int hash; int count; } lines[01000];
+  register int i, h;
+  register int matchcount = 0;
+  int avg_length = 0;
+  int threshold;
+
+  /* Compute a threshold which is 1/4 of average length of these lines.  */
+
+  for (i = start; i < end; i++)
+    avg_length += cost[i];
+
+  avg_length /= end - start;
+  threshold = avg_length / 4;
+
+  bzero (lines, sizeof lines);
+
+  /* Put new lines' hash codes in hash table.
+     Ignore lines shorter than the threshold.
+     Thus, if the lines that are in common
+     are mainly the ones that are short,
+     they won't count.  */
+  for (i = start; i < end; i++)
+    {
+      if (cost[i] > threshold)
+	{
+	  h = newhash[i] & 0777;
+	  lines[h].hash = newhash[i];
+	  lines[h].count++;
+	}
+    }
+
+  /* Look up old line hash codes in the hash table.
+     Count number of matches between old lines and new.  */
+
+  for (i = start; i < end; i++)
+    {
+      h = oldhash[i] & 0777;
+      if (oldhash[i] == lines[h].hash)
+	{
+	  matchcount++;
+	  if (--lines[h].count == 0)
+	    lines[h].hash = 0;
+	}
+    }
+
+  return matchcount;
+}
+
+/* Return a measure of the cost of moving the lines
+   starting with vpos FROM, up to but not including vpos TO,
+   down by AMOUNT lines (AMOUNT may be negative).
+   These are the same arguments that might be given to
+   scroll_screen_lines to perform this scrolling.  */
+
+scroll_cost (screen, from, to, amount)
+     SCREEN_PTR screen;
+     int from, to, amount;
+{
+  /* Compute how many lines, at bottom of screen,
+     will not be involved in actual motion.  */
+  int limit = to;
+  int offset;
+  int height = SCREEN_HEIGHT (screen);
+
+  if (amount > 0)
+    limit += amount;
+  if (! scroll_region_ok)
+    limit = height;
+
+  if (amount == 0)
+    return 0;
+
+  if (amount < 0)
+    {
+      int temp = to;
+      to = from + amount;
+      from = temp + amount;
+      amount = - amount;
+    }
+
+  offset = height - limit;
+
+  return
+    (SCREEN_INSERT_COST (screen)[offset + from]
+     + (amount - 1) * SCREEN_INSERTN_COST (screen)[offset + from]
+     + SCREEN_DELETEN_COST (screen)[offset + to]
+     + (amount - 1) * SCREEN_DELETE_COST (screen)[offset + to]);
+}
+
+/* Calculate the line insertion/deletion
+   overhead and multiply factor values */
+
+static void
+line_ins_del (screen, ov1, pf1, ovn, pfn, ov, mf)
+     SCREEN_PTR screen;
+     int ov1, ovn;
+     int pf1, pfn;
+     register int *ov, *mf;
+{
+  register int i;
+  register int screen_height = SCREEN_HEIGHT (screen);
+  register int insert_overhead = ov1 * 10;
+  register int next_insert_cost = ovn * 10;
+
+  for (i = 0; i <= screen_height; i++)
+    {
+      mf[screen_height - i] = next_insert_cost / 10;
+      next_insert_cost += pfn;
+      ov[screen_height - i] = (insert_overhead + next_insert_cost) / 10;
+      insert_overhead += pf1;
+    }
+}
+
+static void
+ins_del_costs (screen,
+	       one_line_string, multi_string,
+	       setup_string, cleanup_string,
+	       costvec, ncostvec, coefficient)
+     SCREEN_PTR screen;
+     char *one_line_string, *multi_string;
+     char *setup_string, *cleanup_string;
+     int *costvec, *ncostvec;
+     int coefficient;
+{
+  if (multi_string)
+    line_ins_del (screen,
+		  string_cost (multi_string) * coefficient,
+		  per_line_cost (multi_string) * coefficient,
+		  0, 0, costvec, ncostvec);
+  else if (one_line_string)
+    line_ins_del (screen,
+		  string_cost (setup_string) + string_cost (cleanup_string), 0,
+		  string_cost (one_line_string),
+		  per_line_cost (one_line_string),
+		  costvec, ncostvec);
+  else
+    line_ins_del (screen,
+		  9999, 0, 9999, 0,
+		  costvec, ncostvec);
+}
+
+/* Calculate the insert and delete line costs.
+   Note that this is done even when running with a window system
+   because we want to know how long scrolling takes (and avoid it).
+   This must be redone whenever the screen height changes.
+
+   We keep the ID costs in a precomputed array based on the position
+   at which the I or D is performed.  Also, there are two kinds of ID
+   costs: the "once-only" and the "repeated".  This is to handle both
+   those terminals that are able to insert N lines at a time (once-
+   only) and those that must repeatedly insert one line.
+
+   The cost to insert N lines at line L is
+   	    [tt.t_ILov  + (screen_height + 1 - L) * tt.t_ILpf] +
+	N * [tt.t_ILnov + (screen_height + 1 - L) * tt.t_ILnpf]
+
+   ILov represents the basic insert line overhead.  ILpf is the padding
+   required to allow the terminal time to move a line: insertion at line
+   L changes (screen_height + 1 - L) lines.
+
+   The first bracketed expression above is the overhead; the second is
+   the multiply factor.  Both are dependent only on the position at
+   which the insert is performed.  We store the overhead in
+   SCREEN_INSERT_COST (screen) and the multiply factor in
+   SCREEN_INSERTN_COST (screen).  Note however that any insertion
+   must include at least one multiply factor.  Rather than compute this
+   as SCREEN_INSERT_COST (screen)[line]+SCREEN_INSERTN_COST (screen)[line],
+   we add SCREEN_INSERTN_COST (screen) into SCREEN_INSERT_COST (screen).
+   This is reasonable because of the particular algorithm used in calcM.
+
+   Deletion is essentially the same as insertion.
+ */
+
+do_line_insertion_deletion_costs (screen,
+				  ins_line_string, multi_ins_string,
+				  del_line_string, multi_del_string,
+				  setup_string, cleanup_string, coefficient)
+     SCREEN_PTR screen;
+     char *ins_line_string, *multi_ins_string;
+     char *del_line_string, *multi_del_string;
+     char *setup_string, *cleanup_string;
+     int coefficient;
+{
+  if (SCREEN_INSERT_COST (screen) != 0)
+    {
+      SCREEN_INSERT_COST (screen)
+	= (int *) xrealloc (SCREEN_INSERT_COST (screen),
+			    SCREEN_HEIGHT (screen) * sizeof (int));
+      SCREEN_DELETEN_COST (screen)
+	= (int *) xrealloc (SCREEN_DELETEN_COST (screen),
+			    SCREEN_HEIGHT (screen) * sizeof (int));
+      SCREEN_INSERTN_COST (screen)
+	= (int *) xrealloc (SCREEN_INSERTN_COST (screen),
+			    SCREEN_HEIGHT (screen) * sizeof (int));
+      SCREEN_DELETE_COST (screen)
+	= (int *) xrealloc (SCREEN_DELETE_COST (screen),
+			    SCREEN_HEIGHT (screen) * sizeof (int));
+    }
+  else
+    {
+      SCREEN_INSERT_COST (screen)
+	= (int *) xmalloc (SCREEN_HEIGHT (screen) * sizeof (int));
+      SCREEN_DELETEN_COST (screen)
+	= (int *) xmalloc (SCREEN_HEIGHT (screen) * sizeof (int));
+      SCREEN_INSERTN_COST (screen)
+	= (int *) xmalloc (SCREEN_HEIGHT (screen) * sizeof (int));
+      SCREEN_DELETE_COST (screen)
+	= (int *) xmalloc (SCREEN_HEIGHT (screen) * sizeof (int));
+    }
+
+  ins_del_costs (screen,
+		 ins_line_string, multi_ins_string,
+		 setup_string, cleanup_string,
+		 SCREEN_INSERT_COST (screen), SCREEN_INSERTN_COST (screen),
+		 coefficient);
+  ins_del_costs (screen,
+		 del_line_string, multi_del_string,
+		 setup_string, cleanup_string,
+		 SCREEN_DELETEN_COST (screen), SCREEN_DELETE_COST (screen),
+		 coefficient);
+}