[PATCH 1/2] gdb: Add 'tui reg prev' command.

[Andrew Burgess <andrew dot burgess at embecosm dot com>]

There is already a 'tui reg next' command, this adds a symmetric 'tui
reg prev' command.

gdb/ChangeLog:

	* tui/tui-regs.c (tui_reg_prev_command): New function.
	(_initialize_tui_regs): Add 'prev' command for 'tui reg'.
	* reggroups.c (reggroup_prev): New function.
	* reggroups.h (reggroup_prev): Add declaration.  Update comment.

gdb/doc/ChangeLog:

	* gdb.texinfo (TUI Commands): Add 'tui reg prev' details.
---
 gdb/ChangeLog       |  7 +++++++
 gdb/doc/ChangeLog   |  4 ++++
 gdb/doc/gdb.texinfo |  6 ++++++
 gdb/reggroups.c     | 30 ++++++++++++++++++++++++++++++
 gdb/reggroups.h     |  9 ++++++---
 gdb/tui/tui-regs.c  | 33 +++++++++++++++++++++++++++++++++
 6 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 42ef67d..b19e3ca 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2015-05-21  Andrew Burgess  <andrew.burgess@embecosm.com>
 
+	* tui/tui-regs.c (tui_reg_prev_command): New function.
+	(_initialize_tui_regs): Add 'prev' command for 'tui reg'.
+	* reggroups.c (reggroup_prev): New function.
+	* reggroups.h (reggroup_prev): Add declaration.  Update comment.
+
+2015-05-21  Andrew Burgess  <andrew.burgess@embecosm.com>
+
 	* tui/tui-regs.c (tui_reg_next_command): Use NULL not 0.
 
 2015-05-21  Andrew Burgess  <andrew.burgess@embecosm.com>
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index f8b0487..ef38740 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,7 @@
+2015-05-21  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* gdb.texinfo (TUI Commands): Add 'tui reg prev' details.
+
 2015-05-16  Doug Evans  <xdje42@gmail.com>
 
 	* guile.texi (Memory Ports in Guile): Document support for unbuffered
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1665372..44dff6e 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -25003,6 +25003,12 @@ their order is target specific.  The predefined register groups are the
 following: @code{general}, @code{float}, @code{system}, @code{vector},
 @code{all}, @code{save}, @code{restore}.
 
+@item tui reg prev
+Show the previous register group.  The list of register groups as well
+as their order is target specific.  The predefined register groups are
+the following: @code{general}, @code{float}, @code{system},
+@code{vector}, @code{all}, @code{save}, @code{restore}.
+
 @item tui reg system
 Show the system registers in the register window.
 
diff --git a/gdb/reggroups.c b/gdb/reggroups.c
index cbafc01..27be704 100644
--- a/gdb/reggroups.c
+++ b/gdb/reggroups.c
@@ -150,6 +150,36 @@ reggroup_next (struct gdbarch *gdbarch, struct reggroup *last)
   return NULL;
 }
 
+struct reggroup *
+reggroup_prev (struct gdbarch *gdbarch, struct reggroup *last)
+{
+  struct reggroups *groups;
+  struct reggroup_el *el;
+  struct reggroup *prev;
+
+  /* Don't allow this function to be called during architecture
+     creation.  If there are no groups, use the default groups list.  */
+  groups = gdbarch_data (gdbarch, reggroups_data);
+  gdb_assert (groups != NULL);
+  if (groups->first == NULL)
+    {
+      groups = &default_groups;
+      gdb_assert (groups->first != NULL);
+    }
+
+  /* Return the first/next reggroup.  */
+  if (last == NULL)
+    return groups->first->group;
+  prev = NULL;
+  for (el = groups->first; el != NULL; el = el->next)
+    {
+      if (el->group == last)
+	return prev;
+      prev = el->group;
+    }
+  return NULL;
+}
+
 /* Is REGNUM a member of REGGROUP?  */
 int
 default_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
diff --git a/gdb/reggroups.h b/gdb/reggroups.h
index 2ad74bc..bb0d6e7 100644
--- a/gdb/reggroups.h
+++ b/gdb/reggroups.h
@@ -49,11 +49,14 @@ extern void reggroup_add (struct gdbarch *gdbarch, struct reggroup *group);
 extern const char *reggroup_name (struct reggroup *reggroup);
 extern enum reggroup_type reggroup_type (struct reggroup *reggroup);
 
-/* Interator for the architecture's register groups.  Pass in NULL,
-   returns the first group.  Pass in a group, returns the next group,
-   or NULL when the last group is reached.  */
+/* Iterators for the architecture's register groups.  Pass in NULL, returns
+   the first group.  Pass in a group, returns the next or previous group,
+   or NULL when either the end or the beginning of the group list is
+   reached.  */
 extern struct reggroup *reggroup_next (struct gdbarch *gdbarch,
 				       struct reggroup *last);
+extern struct reggroup *reggroup_prev (struct gdbarch *gdbarch,
+				       struct reggroup *last);
 
 /* Is REGNUM a member of REGGROUP?  */
 extern int default_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
diff --git a/gdb/tui/tui-regs.c b/gdb/tui/tui-regs.c
index 8d4c0f8..8dbcda1 100644
--- a/gdb/tui/tui-regs.c
+++ b/gdb/tui/tui-regs.c
@@ -576,6 +576,36 @@ tui_reg_next_command (char *arg, int from_tty)
 }
 
 static void
+tui_reg_prev_command (char *arg, int from_tty)
+{
+  struct gdbarch *gdbarch = get_current_arch ();
+
+  if (TUI_DATA_WIN != NULL)
+    {
+      struct reggroup *group
+        = TUI_DATA_WIN->detail.data_display_info.current_group;
+
+      group = reggroup_prev (gdbarch, group);
+      if (group == NULL)
+	{
+	  struct reggroup *prev, *next;
+
+	  next = reggroup_next (gdbarch, NULL);
+	  prev = NULL;
+	  while (next)
+	    {
+	      prev = next;
+	      next = reggroup_next (gdbarch, next);
+	    }
+	  group = prev;
+	}
+
+      if (group)
+        tui_show_registers (group);
+    }
+}
+
+static void
 tui_reg_float_command (char *arg, int from_tty)
 {
   tui_show_registers (float_reggroup);
@@ -630,6 +660,9 @@ _initialize_tui_regs (void)
   add_cmd ("next", class_tui, tui_reg_next_command,
            _("Display next register group."),
            &tuireglist);
+  add_cmd ("prev", class_tui, tui_reg_prev_command,
+           _("Display previous register group."),
+           &tuireglist);
 }
 
 
-- 
2.4.0