xref: /dragonfly/contrib/gdb-7/gdb/tui/tui-regs.c (revision 92fc8b5c)
1 /* TUI display registers in window.
2 
3    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2007, 2008, 2009,
4    2010 Free Software Foundation, Inc.
5 
6    Contributed by Hewlett-Packard Company.
7 
8    This file is part of GDB.
9 
10    This program is free software; you can redistribute it and/or modify
11    it under the terms of the GNU General Public License as published by
12    the Free Software Foundation; either version 3 of the License, or
13    (at your option) any later version.
14 
15    This program is distributed in the hope that it will be useful,
16    but WITHOUT ANY WARRANTY; without even the implied warranty of
17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18    GNU General Public License for more details.
19 
20    You should have received a copy of the GNU General Public License
21    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
22 
23 #include "defs.h"
24 #include "arch-utils.h"
25 #include "tui/tui.h"
26 #include "tui/tui-data.h"
27 #include "symtab.h"
28 #include "gdbtypes.h"
29 #include "gdbcmd.h"
30 #include "frame.h"
31 #include "regcache.h"
32 #include "inferior.h"
33 #include "target.h"
34 #include "gdb_string.h"
35 #include "tui/tui-layout.h"
36 #include "tui/tui-win.h"
37 #include "tui/tui-windata.h"
38 #include "tui/tui-wingeneral.h"
39 #include "tui/tui-file.h"
40 #include "tui/tui-regs.h"
41 #include "reggroups.h"
42 #include "valprint.h"
43 
44 #include "gdb_curses.h"
45 
46 
47 /*****************************************
48 ** STATIC LOCAL FUNCTIONS FORWARD DECLS    **
49 ******************************************/
50 static void
51 tui_display_register (struct tui_data_element *data,
52                       struct tui_gen_win_info *win_info);
53 
54 static enum tui_status tui_show_register_group (struct reggroup *group,
55 						struct frame_info *frame,
56 						int refresh_values_only);
57 
58 static enum tui_status tui_get_register (struct frame_info *frame,
59 					 struct tui_data_element *data,
60 					 int regnum, int *changedp);
61 
62 static void tui_register_format (struct frame_info *,
63 				 struct tui_data_element*, int);
64 
65 static void tui_scroll_regs_forward_command (char *, int);
66 static void tui_scroll_regs_backward_command (char *, int);
67 
68 
69 
70 /*****************************************
71 ** PUBLIC FUNCTIONS                     **
72 ******************************************/
73 
74 /* Answer the number of the last line in the regs display.  If there
75    are no registers (-1) is returned.  */
76 int
77 tui_last_regs_line_no (void)
78 {
79   int num_lines = (-1);
80 
81   if (TUI_DATA_WIN->detail.data_display_info.regs_content_count > 0)
82     {
83       num_lines = (TUI_DATA_WIN->detail.data_display_info.regs_content_count /
84 		  TUI_DATA_WIN->detail.data_display_info.regs_column_count);
85       if (TUI_DATA_WIN->detail.data_display_info.regs_content_count %
86 	  TUI_DATA_WIN->detail.data_display_info.regs_column_count)
87 	num_lines++;
88     }
89   return num_lines;
90 }
91 
92 
93 /* Answer the line number that the register element at element_no is
94    on.  If element_no is greater than the number of register elements
95    there are, -1 is returned.  */
96 int
97 tui_line_from_reg_element_no (int element_no)
98 {
99   if (element_no < TUI_DATA_WIN->detail.data_display_info.regs_content_count)
100     {
101       int i, line = (-1);
102 
103       i = 1;
104       while (line == (-1))
105 	{
106 	  if (element_no <
107 	      (TUI_DATA_WIN->detail.data_display_info.regs_column_count * i))
108 	    line = i - 1;
109 	  else
110 	    i++;
111 	}
112 
113       return line;
114     }
115   else
116     return (-1);
117 }
118 
119 
120 /* Answer the index of the first element in line_no.  If line_no is
121    past the register area (-1) is returned.  */
122 int
123 tui_first_reg_element_no_inline (int line_no)
124 {
125   if ((line_no * TUI_DATA_WIN->detail.data_display_info.regs_column_count)
126       <= TUI_DATA_WIN->detail.data_display_info.regs_content_count)
127     return ((line_no + 1) *
128 	    TUI_DATA_WIN->detail.data_display_info.regs_column_count) -
129       TUI_DATA_WIN->detail.data_display_info.regs_column_count;
130   else
131     return (-1);
132 }
133 
134 
135 /* Answer the index of the last element in line_no.  If line_no is
136    past the register area (-1) is returned.  */
137 int
138 tui_last_reg_element_no_in_line (int line_no)
139 {
140   if ((line_no * TUI_DATA_WIN->detail.data_display_info.regs_column_count) <=
141       TUI_DATA_WIN->detail.data_display_info.regs_content_count)
142     return ((line_no + 1) *
143 	    TUI_DATA_WIN->detail.data_display_info.regs_column_count) - 1;
144   else
145     return (-1);
146 }
147 
148 /* Show the registers of the given group in the data window
149    and refresh the window.  */
150 void
151 tui_show_registers (struct reggroup *group)
152 {
153   enum tui_status ret = TUI_FAILURE;
154   struct tui_data_info *display_info;
155 
156   /* Make sure the curses mode is enabled.  */
157   tui_enable ();
158 
159   /* Make sure the register window is visible.  If not, select an
160      appropriate layout.  */
161   if (TUI_DATA_WIN == NULL || !TUI_DATA_WIN->generic.is_visible)
162     tui_set_layout_for_display_command (DATA_NAME);
163 
164   display_info = &TUI_DATA_WIN->detail.data_display_info;
165   if (group == 0)
166     group = general_reggroup;
167 
168   /* Say that registers should be displayed, even if there is a
169      problem.  */
170   display_info->display_regs = TRUE;
171 
172   if (target_has_registers && target_has_stack && target_has_memory)
173     {
174       ret = tui_show_register_group (group, get_current_frame (),
175                                      group == display_info->current_group);
176     }
177   if (ret == TUI_FAILURE)
178     {
179       display_info->current_group = 0;
180       tui_erase_data_content (NO_REGS_STRING);
181     }
182   else
183     {
184       int i;
185 
186       /* Clear all notation of changed values.  */
187       for (i = 0; i < display_info->regs_content_count; i++)
188 	{
189 	  struct tui_gen_win_info *data_item_win;
190           struct tui_win_element *win;
191 
192 	  data_item_win = &display_info->regs_content[i]
193             ->which_element.data_window;
194           win = (struct tui_win_element *) data_item_win->content[0];
195           win->which_element.data.highlight = FALSE;
196 	}
197       display_info->current_group = group;
198       tui_display_all_data ();
199     }
200 }
201 
202 
203 /* Set the data window to display the registers of the register group
204    using the given frame.  Values are refreshed only when
205    refresh_values_only is TRUE.  */
206 
207 static enum tui_status
208 tui_show_register_group (struct reggroup *group,
209                          struct frame_info *frame,
210 			 int refresh_values_only)
211 {
212   struct gdbarch *gdbarch = get_frame_arch (frame);
213   enum tui_status ret = TUI_FAILURE;
214   int nr_regs;
215   int allocated_here = FALSE;
216   int regnum, pos;
217   char title[80];
218   struct tui_data_info *display_info = &TUI_DATA_WIN->detail.data_display_info;
219 
220   /* Make a new title showing which group we display.  */
221   snprintf (title, sizeof (title) - 1, "Register group: %s",
222             reggroup_name (group));
223   xfree (TUI_DATA_WIN->generic.title);
224   TUI_DATA_WIN->generic.title = xstrdup (title);
225 
226   /* See how many registers must be displayed.  */
227   nr_regs = 0;
228   for (regnum = 0;
229        regnum < gdbarch_num_regs (gdbarch)
230 		+ gdbarch_num_pseudo_regs (gdbarch);
231        regnum++)
232     {
233       /* Must be in the group and have a name.  */
234       if (gdbarch_register_reggroup_p (gdbarch, regnum, group)
235           && gdbarch_register_name (gdbarch, regnum) != 0)
236         nr_regs++;
237     }
238 
239   if (display_info->regs_content_count > 0 && !refresh_values_only)
240     {
241       tui_free_data_content (display_info->regs_content,
242                              display_info->regs_content_count);
243       display_info->regs_content_count = 0;
244     }
245 
246   if (display_info->regs_content_count <= 0)
247     {
248       display_info->regs_content = tui_alloc_content (nr_regs, DATA_WIN);
249       allocated_here = TRUE;
250       refresh_values_only = FALSE;
251     }
252 
253   if (display_info->regs_content != (tui_win_content) NULL)
254     {
255       if (!refresh_values_only || allocated_here)
256 	{
257 	  TUI_DATA_WIN->generic.content = (void*) NULL;
258 	  TUI_DATA_WIN->generic.content_size = 0;
259 	  tui_add_content_elements (&TUI_DATA_WIN->generic, nr_regs);
260 	  display_info->regs_content
261             = (tui_win_content) TUI_DATA_WIN->generic.content;
262 	  display_info->regs_content_count = nr_regs;
263 	}
264 
265       /* Now set the register names and values.  */
266       pos = 0;
267       for (regnum = 0;
268 	   regnum < gdbarch_num_regs (gdbarch)
269 		    + gdbarch_num_pseudo_regs (gdbarch);
270 	   regnum++)
271         {
272 	  struct tui_gen_win_info *data_item_win;
273           struct tui_data_element *data;
274           const char *name;
275 
276           if (!gdbarch_register_reggroup_p (gdbarch, regnum, group))
277             continue;
278 
279           name = gdbarch_register_name (gdbarch, regnum);
280           if (name == 0)
281             continue;
282 
283 	  data_item_win =
284             &display_info->regs_content[pos]->which_element.data_window;
285           data =
286             &((struct tui_win_element *) data_item_win->content[0])->which_element.data;
287           if (data)
288             {
289               if (!refresh_values_only)
290                 {
291                   data->item_no = regnum;
292                   data->name = name;
293                   data->highlight = FALSE;
294                 }
295               if (data->value == (void*) NULL)
296                 data->value = (void*) xmalloc (MAX_REGISTER_SIZE);
297 
298               tui_get_register (frame, data, regnum, 0);
299             }
300           pos++;
301 	}
302 
303       TUI_DATA_WIN->generic.content_size =
304 	display_info->regs_content_count + display_info->data_content_count;
305       ret = TUI_SUCCESS;
306     }
307 
308   return ret;
309 }
310 
311 /* Function to display the registers in the content from
312    'start_element_no' until the end of the register content or the end
313    of the display height.  No checking for displaying past the end of
314    the registers is done here.  */
315 void
316 tui_display_registers_from (int start_element_no)
317 {
318   struct tui_data_info *display_info = &TUI_DATA_WIN->detail.data_display_info;
319 
320   if (display_info->regs_content != (tui_win_content) NULL
321       && display_info->regs_content_count > 0)
322     {
323       int i = start_element_no;
324       int j, item_win_width, cur_y;
325 
326       int max_len = 0;
327       for (i = 0; i < display_info->regs_content_count; i++)
328         {
329           struct tui_data_element *data;
330           struct tui_gen_win_info *data_item_win;
331           char *p;
332           int len;
333 
334           data_item_win = &display_info->regs_content[i]->which_element.data_window;
335           data = &((struct tui_win_element *)
336                    data_item_win->content[0])->which_element.data;
337           len = 0;
338           p = data->content;
339           if (p != 0)
340             while (*p)
341               {
342                 if (*p++ == '\t')
343                   len = 8 * ((len / 8) + 1);
344                 else
345                   len++;
346               }
347 
348           if (len > max_len)
349             max_len = len;
350         }
351       item_win_width = max_len + 1;
352       i = start_element_no;
353 
354       display_info->regs_column_count =
355         (TUI_DATA_WIN->generic.width - 2) / item_win_width;
356       if (display_info->regs_column_count == 0)
357         display_info->regs_column_count = 1;
358       item_win_width =
359         (TUI_DATA_WIN->generic.width - 2) / display_info->regs_column_count;
360 
361       /* Now create each data "sub" window, and write the display into
362 	 it.  */
363       cur_y = 1;
364       while (i < display_info->regs_content_count
365 	     && cur_y <= TUI_DATA_WIN->generic.viewport_height)
366 	{
367 	  for (j = 0;
368 	       j < display_info->regs_column_count
369 		 && i < display_info->regs_content_count;
370 	       j++)
371 	    {
372 	      struct tui_gen_win_info *data_item_win;
373 	      struct tui_data_element *data_element_ptr;
374 
375 	      /* Create the window if necessary.  */
376 	      data_item_win = &display_info->regs_content[i]
377                 ->which_element.data_window;
378 	      data_element_ptr = &((struct tui_win_element *)
379 				 data_item_win->content[0])->which_element.data;
380               if (data_item_win->handle != (WINDOW*) NULL
381                   && (data_item_win->height != 1
382                       || data_item_win->width != item_win_width
383                       || data_item_win->origin.x != (item_win_width * j) + 1
384                       || data_item_win->origin.y != cur_y))
385                 {
386                   tui_delete_win (data_item_win->handle);
387                   data_item_win->handle = 0;
388                 }
389 
390 	      if (data_item_win->handle == (WINDOW *) NULL)
391 		{
392 		  data_item_win->height = 1;
393 		  data_item_win->width = item_win_width;
394 		  data_item_win->origin.x = (item_win_width * j) + 1;
395 		  data_item_win->origin.y = cur_y;
396 		  tui_make_window (data_item_win, DONT_BOX_WINDOW);
397                   scrollok (data_item_win->handle, FALSE);
398 		}
399               touchwin (data_item_win->handle);
400 
401 	      /* Get the printable representation of the register
402                  and display it.  */
403               tui_display_register (data_element_ptr, data_item_win);
404 	      i++;		/* Next register.  */
405 	    }
406 	  cur_y++;		/* Next row.  */
407 	}
408     }
409 }
410 
411 
412 /* Function to display the registers in the content from
413    'start_element_no' on 'start_line_no' until the end of the register
414    content or the end of the display height.  This function checks
415    that we won't display off the end of the register display.  */
416 static void
417 tui_display_reg_element_at_line (int start_element_no,
418 				 int start_line_no)
419 {
420   if (TUI_DATA_WIN->detail.data_display_info.regs_content != (tui_win_content) NULL
421       && TUI_DATA_WIN->detail.data_display_info.regs_content_count > 0)
422     {
423       int element_no = start_element_no;
424 
425       if (start_element_no != 0 && start_line_no != 0)
426 	{
427 	  int last_line_no, first_line_on_last_page;
428 
429 	  last_line_no = tui_last_regs_line_no ();
430 	  first_line_on_last_page = last_line_no - (TUI_DATA_WIN->generic.height - 2);
431 	  if (first_line_on_last_page < 0)
432 	    first_line_on_last_page = 0;
433 
434 	  /* If there is no other data displayed except registers, and
435 	     the element_no causes us to scroll past the end of the
436 	     registers, adjust what element to really start the
437 	     display at.  */
438 	  if (TUI_DATA_WIN->detail.data_display_info.data_content_count <= 0
439 	      && start_line_no > first_line_on_last_page)
440 	    element_no = tui_first_reg_element_no_inline (first_line_on_last_page);
441 	}
442       tui_display_registers_from (element_no);
443     }
444 }
445 
446 
447 
448 /* Function to display the registers starting at line line_no in the
449    data window.  Answers the line number that the display actually
450    started from.  If nothing is displayed (-1) is returned.  */
451 int
452 tui_display_registers_from_line (int line_no,
453 				 int force_display)
454 {
455   if (TUI_DATA_WIN->detail.data_display_info.regs_content_count > 0)
456     {
457       int line, element_no;
458 
459       if (line_no < 0)
460 	line = 0;
461       else if (force_display)
462 	{ /* If we must display regs (force_display is true), then
463 	     make sure that we don't display off the end of the
464 	     registers.  */
465 	  if (line_no >= tui_last_regs_line_no ())
466 	    {
467 	      if ((line = tui_line_from_reg_element_no (
468 		 TUI_DATA_WIN->detail.data_display_info.regs_content_count - 1)) < 0)
469 		line = 0;
470 	    }
471 	  else
472 	    line = line_no;
473 	}
474       else
475 	line = line_no;
476 
477       element_no = tui_first_reg_element_no_inline (line);
478       if (element_no < TUI_DATA_WIN->detail.data_display_info.regs_content_count)
479 	tui_display_reg_element_at_line (element_no, line);
480       else
481 	line = (-1);
482 
483       return line;
484     }
485 
486   return (-1);			/* Nothing was displayed.  */
487 }
488 
489 
490 /* This function check all displayed registers for changes in values,
491    given a particular frame.  If the values have changed, they are
492    updated with the new value and highlighted.  */
493 void
494 tui_check_register_values (struct frame_info *frame)
495 {
496   if (TUI_DATA_WIN != NULL
497       && TUI_DATA_WIN->generic.is_visible)
498     {
499       struct tui_data_info *display_info
500         = &TUI_DATA_WIN->detail.data_display_info;
501 
502       if (display_info->regs_content_count <= 0
503 	  && display_info->display_regs)
504 	tui_show_registers (display_info->current_group);
505       else
506 	{
507 	  int i;
508 
509 	  for (i = 0; (i < display_info->regs_content_count); i++)
510 	    {
511 	      struct tui_data_element *data;
512 	      struct tui_gen_win_info *data_item_win_ptr;
513 	      int was_hilighted;
514 
515 	      data_item_win_ptr = &display_info->regs_content[i]->
516                 which_element.data_window;
517 	      data = &((struct tui_win_element *)
518                        data_item_win_ptr->content[0])->which_element.data;
519 	      was_hilighted = data->highlight;
520 
521               tui_get_register (frame, data,
522                                 data->item_no, &data->highlight);
523 
524 	      if (data->highlight || was_hilighted)
525 		{
526                   tui_display_register (data, data_item_win_ptr);
527 		}
528 	    }
529 	}
530     }
531 }
532 
533 /* Display a register in a window.  If hilite is TRUE, then the value
534    will be displayed in reverse video.  */
535 static void
536 tui_display_register (struct tui_data_element *data,
537                       struct tui_gen_win_info *win_info)
538 {
539   if (win_info->handle != (WINDOW *) NULL)
540     {
541       int i;
542 
543       if (data->highlight)
544 	/* We ignore the return value, casting it to void in order to avoid
545 	   a compiler warning.  The warning itself was introduced by a patch
546 	   to ncurses 5.7 dated 2009-08-29, changing this macro to expand
547 	   to code that causes the compiler to generate an unused-value
548 	   warning.  */
549 	(void) wstandout (win_info->handle);
550 
551       wmove (win_info->handle, 0, 0);
552       for (i = 1; i < win_info->width; i++)
553         waddch (win_info->handle, ' ');
554       wmove (win_info->handle, 0, 0);
555       if (data->content)
556         waddstr (win_info->handle, data->content);
557 
558       if (data->highlight)
559 	/* We ignore the return value, casting it to void in order to avoid
560 	   a compiler warning.  The warning itself was introduced by a patch
561 	   to ncurses 5.7 dated 2009-08-29, changing this macro to expand
562 	   to code that causes the compiler to generate an unused-value
563 	   warning.  */
564 	(void) wstandend (win_info->handle);
565       tui_refresh_win (win_info);
566     }
567 }
568 
569 static void
570 tui_reg_next_command (char *arg, int from_tty)
571 {
572   struct gdbarch *gdbarch = get_current_arch ();
573 
574   if (TUI_DATA_WIN != 0)
575     {
576       struct reggroup *group
577         = TUI_DATA_WIN->detail.data_display_info.current_group;
578 
579       group = reggroup_next (gdbarch, group);
580       if (group == 0)
581         group = reggroup_next (gdbarch, 0);
582 
583       if (group)
584         tui_show_registers (group);
585     }
586 }
587 
588 static void
589 tui_reg_float_command (char *arg, int from_tty)
590 {
591   tui_show_registers (float_reggroup);
592 }
593 
594 static void
595 tui_reg_general_command (char *arg, int from_tty)
596 {
597   tui_show_registers (general_reggroup);
598 }
599 
600 static void
601 tui_reg_system_command (char *arg, int from_tty)
602 {
603   tui_show_registers (system_reggroup);
604 }
605 
606 static struct cmd_list_element *tuireglist;
607 
608 static void
609 tui_reg_command (char *args, int from_tty)
610 {
611   printf_unfiltered (_("\"tui reg\" must be followed by the name of a "
612                      "tui reg command.\n"));
613   help_list (tuireglist, "tui reg ", -1, gdb_stdout);
614 }
615 
616 /* Provide a prototype to silence -Wmissing-prototypes.  */
617 extern initialize_file_ftype _initialize_tui_regs;
618 
619 void
620 _initialize_tui_regs (void)
621 {
622   struct cmd_list_element **tuicmd;
623 
624   tuicmd = tui_get_cmd_list ();
625 
626   add_prefix_cmd ("reg", class_tui, tui_reg_command,
627                   _("TUI commands to control the register window."),
628                   &tuireglist, "tui reg ", 0,
629                   tuicmd);
630 
631   add_cmd ("float", class_tui, tui_reg_float_command,
632            _("Display only floating point registers."),
633            &tuireglist);
634   add_cmd ("general", class_tui, tui_reg_general_command,
635            _("Display only general registers."),
636            &tuireglist);
637   add_cmd ("system", class_tui, tui_reg_system_command,
638            _("Display only system registers."),
639            &tuireglist);
640   add_cmd ("next", class_tui, tui_reg_next_command,
641            _("Display next register group."),
642            &tuireglist);
643 
644   if (xdb_commands)
645     {
646       add_com ("fr", class_tui, tui_reg_float_command,
647 	       _("Display only floating point registers\n"));
648       add_com ("gr", class_tui, tui_reg_general_command,
649 	       _("Display only general registers\n"));
650       add_com ("sr", class_tui, tui_reg_system_command,
651 	       _("Display only special registers\n"));
652       add_com ("+r", class_tui, tui_scroll_regs_forward_command,
653 	       _("Scroll the registers window forward\n"));
654       add_com ("-r", class_tui, tui_scroll_regs_backward_command,
655 	       _("Scroll the register window backward\n"));
656     }
657 }
658 
659 
660 /*****************************************
661 ** STATIC LOCAL FUNCTIONS                 **
662 ******************************************/
663 
664 extern int pagination_enabled;
665 
666 static void
667 tui_restore_gdbout (void *ui)
668 {
669   ui_file_delete (gdb_stdout);
670   gdb_stdout = (struct ui_file*) ui;
671   pagination_enabled = 1;
672 }
673 
674 /* Get the register from the frame and make a printable representation
675    of it in the data element.  */
676 static void
677 tui_register_format (struct frame_info *frame,
678                      struct tui_data_element *data_element,
679 		     int regnum)
680 {
681   struct gdbarch *gdbarch = get_frame_arch (frame);
682   struct ui_file *stream;
683   struct ui_file *old_stdout;
684   const char *name;
685   struct cleanup *cleanups;
686   char *p, *s;
687   struct type *type = register_type (gdbarch, regnum);
688 
689   name = gdbarch_register_name (gdbarch, regnum);
690   if (name == 0)
691     {
692       return;
693     }
694 
695   pagination_enabled = 0;
696   old_stdout = gdb_stdout;
697   stream = tui_sfileopen (256);
698   gdb_stdout = stream;
699   cleanups = make_cleanup (tui_restore_gdbout, (void*) old_stdout);
700   if (TYPE_VECTOR (type) != 0 && 0)
701     {
702       gdb_byte buf[MAX_REGISTER_SIZE];
703       int len;
704       struct value_print_options opts;
705 
706       len = register_size (gdbarch, regnum);
707       fprintf_filtered (stream, "%-14s ", name);
708       get_frame_register (frame, regnum, buf);
709       get_formatted_print_options (&opts, 'f');
710       print_scalar_formatted (buf, type, &opts, len, stream);
711     }
712   else
713     {
714       gdbarch_print_registers_info (gdbarch, stream,
715                                     frame, regnum, 1);
716     }
717 
718   /* Save formatted output in the buffer.  */
719   p = tui_file_get_strbuf (stream);
720 
721   /* Remove the possible \n.  */
722   s = strrchr (p, '\n');
723   if (s && s[1] == 0)
724     *s = 0;
725 
726   xfree (data_element->content);
727   data_element->content = xstrdup (p);
728   do_cleanups (cleanups);
729 }
730 
731 /* Get the register value from the given frame and format it for the
732    display.  When changep is set, check if the new register value has
733    changed with respect to the previous call.  */
734 static enum tui_status
735 tui_get_register (struct frame_info *frame,
736                   struct tui_data_element *data,
737 		  int regnum, int *changedp)
738 {
739   enum tui_status ret = TUI_FAILURE;
740 
741   if (changedp)
742     *changedp = FALSE;
743   if (target_has_registers)
744     {
745       gdb_byte buf[MAX_REGISTER_SIZE];
746 
747       get_frame_register (frame, regnum, buf);
748       if (changedp)
749 	{
750 	  struct gdbarch *gdbarch = get_frame_arch (frame);
751 	  int size = register_size (gdbarch, regnum);
752 	  char *old = (char*) data->value;
753 	  int i;
754 
755 	  for (i = 0; i < size; i++)
756 	    if (buf[i] != old[i])
757 	      {
758 		*changedp = TRUE;
759 		old[i] = buf[i];
760 	      }
761 	}
762 
763       /* Reformat the data content if the value changed.  */
764       if (changedp == 0 || *changedp == TRUE)
765 	tui_register_format (frame, data, regnum);
766 
767       ret = TUI_SUCCESS;
768     }
769   return ret;
770 }
771 
772 static void
773 tui_scroll_regs_forward_command (char *arg, int from_tty)
774 {
775   tui_scroll (FORWARD_SCROLL, TUI_DATA_WIN, 1);
776 }
777 
778 
779 static void
780 tui_scroll_regs_backward_command (char *arg, int from_tty)
781 {
782   tui_scroll (BACKWARD_SCROLL, TUI_DATA_WIN, 1);
783 }
784