[v5] gdb: Add new 'print nibbles' feature

Message ID SYBP282MB0300831BC87D7641C80254BADDB19@SYBP282MB0300.AUSP282.PROD.OUTLOOK.COM
State New
Headers show
Series
  • [v5] gdb: Add new 'print nibbles' feature
Related show

Commit Message

Lancelot SIX via Gdb-patches Oct. 7, 2021, 2:44 p.m.
Make an introduction of a new print setting that can be set by 'set
print nibbles [on|off]'.  The default value is OFF, and it would be
changed by users manually.

Of course, 'show print nibbles' is also included in the patch.

The new feature could display binary values in groups, and each group
has four bits.

The motivation behind this work is to enable users to more quickly
distinguish the position of any bit on the binary value.

Here's a GDB session before this patch is applied.
  (gdb) print var_a
  $1 = 1230
  (gdb) print/t var_a
  $2 = 10011001110

With this patch applied, we have a new print setting to use.
  (gdb) print var_a
  $1 = 1230
  (gdb) print/t var_a
  $2 = 10011001110
  (gdb) set print nibbles on
  (gdb) print/t a
  $3 = 100 1100 1110

Tested on x86_64-linux(little-endian) and mips-linux(big-endian).

gdb/ChangeLog:
2021-09-03  Enze Li  <lienze2010@hotmail.com>

	* NEWS: Metion new command.
	* printcmd.c (print_scalar_formatted): Add new parameter and pass
	it to print_binary_chars.
	* valprint.c (struct value_print_options) <nibblesprint>:
	New member.
	(show_binary_groups): New function.
	(print_binary_chars): Add new parameter `value_print_option *`
	and use it.
	* valprint.h (struct value_print_options):
	(print_binary_chars): Add new parameter to declaration.

gdb/doc/ChangeLog:
2021-09-03  Enze Li  <lienze2010@hotmail.com>

	* gdb.texinfo (Print Settings): Document 'print nibbles'.

gdb/testsuite/ChangeLog:
2021-09-03  Enze Li  <lienze2010@hotmail.com>

	* gdb.base/printcmds.exp: Update to use new
	'print nibbles' command.
	* gdb.base/options.exp: Add -nibbles in the print completion list.
---
 gdb/NEWS                             |  5 ++++
 gdb/doc/gdb.texinfo                  | 35 ++++++++++++++++++++++++----
 gdb/printcmd.c                       |  2 +-
 gdb/testsuite/gdb.base/options.exp   |  1 +
 gdb/testsuite/gdb.base/printcmds.exp | 14 +++++++++++
 gdb/valprint.c                       | 28 +++++++++++++++++++++-
 gdb/valprint.h                       |  6 ++++-
 7 files changed, 84 insertions(+), 7 deletions(-)

-- 
2.30.2

Patch

diff --git a/gdb/NEWS b/gdb/NEWS
index 7ca1f842cb1..ef1127da27b 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -170,6 +170,11 @@  set debug event-loop
 show debug event-loop
   Control the display of debug output about GDB's event loop.
 
+set print nibbles [on|off]
+show print nibbles
+  This controls whether the 'print/t' command will display binary values
+  in groups of four bits, known as "nibbles".  The default is 'off'.
+
 set print memory-tag-violations
 show print memory-tag-violations
   Control whether to display additional information about memory tag violations
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index a6f207a41a7..d59fbe13457 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -2141,10 +2141,10 @@  on @code{-} after the command name.  For example:
 
 @smallexample
 (@value{GDBP}) print -@key{TAB}@key{TAB}
--address         -max-depth       -raw-values      -union
--array           -null-stop       -repeats         -vtbl
--array-indexes   -object          -static-members
--elements        -pretty          -symbol
+-address         -max-depth       -pretty          -symbol
+-array           -nibbles         -raw-values      -union
+-array-indexes   -null-stop       -repeats         -vtbl
+-elements        -object          -static-members
 @end smallexample
 
 Completion will in some cases guide you with a suggestion of what kind
@@ -10003,6 +10003,10 @@  Set limit on string chars or array elements to print.  The value
 Set the threshold after which nested structures are replaced with
 ellipsis.  Related setting: @ref{set print max-depth}.
 
+@item -nibbles [@code{on}|@code{off}]
+Set whether to print binary values in groups of four bits, known
+as ``nibbles''. @xref{set print nibbles}.
+
 @item -null-stop [@code{on}|@code{off}]
 Set printing of char arrays to stop at first null char.  Related
 setting: @ref{set print null-stop}.
@@ -11361,6 +11365,29 @@  Stop printing element indexes when displaying arrays.
 Show whether the index of each element is printed when displaying
 arrays.
 
+@anchor{set print nibbles}
+@item set print nibbles
+@itemx set print nibbles on
+@cindex print binary values in groups of four bits
+Print binary values in groups of four bits, known as @dfn{nibbles},
+when using the print command of @value{GDBN} with the option @samp{/t}.
+For example, this is what it looks like with @code{set print nibbles on}:
+
+@smallexample
+@group
+(@value{GDBP}) print val_flags
+$1 = 1230
+(@value{GDBP}) print/t val_flags
+$2 = 100 1100 1110
+@end group
+@end smallexample
+
+@item set print nibbles off
+Don't printing binary values in groups.  This is the default.
+
+@item show print nibbles
+Show whether to print binary values in groups of four bits.
+
 @anchor{set print elements}
 @item set print elements @var{number-of-elements}
 @itemx set print elements unlimited
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 2fe3f4b0cc5..62713f1a91f 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -490,7 +490,7 @@  print_scalar_formatted (const gdb_byte *valaddr, struct type *type,
       break;
 
     case 't':
-      print_binary_chars (stream, valaddr, len, byte_order, size > 0);
+      print_binary_chars (stream, valaddr, len, byte_order, size > 0, options);
       break;
     case 'x':
       print_hex_chars (stream, valaddr, len, byte_order, size > 0);
diff --git a/gdb/testsuite/gdb.base/options.exp b/gdb/testsuite/gdb.base/options.exp
index 94372aa9fc7..1a680a3baf4 100644
--- a/gdb/testsuite/gdb.base/options.exp
+++ b/gdb/testsuite/gdb.base/options.exp
@@ -168,6 +168,7 @@  proc_with_prefix test-print {{prefix ""}} {
 	"-elements"
 	"-max-depth"
 	"-memory-tag-violations"
+	"-nibbles"
 	"-null-stop"
 	"-object"
 	"-pretty"
diff --git a/gdb/testsuite/gdb.base/printcmds.exp b/gdb/testsuite/gdb.base/printcmds.exp
index b2f90aaff10..75abe79a70d 100644
--- a/gdb/testsuite/gdb.base/printcmds.exp
+++ b/gdb/testsuite/gdb.base/printcmds.exp
@@ -690,6 +690,19 @@  proc test_print_char_arrays {} {
     gdb_test_no_output "set print address off" "address off char arrays"
 }
 
+proc test_print_nibbles {} {
+    gdb_test_no_output "set print nibbles on"
+    gdb_test "p/t 0"		" = 0"
+    gdb_test "p/t 0x0"		" = 0"
+    gdb_test "p/t 0x30"		" = 11 0000"
+    gdb_test "p/t 0xff"		" = 1111 1111"
+    gdb_test "p/t 0x0f"		" = 1111"
+    gdb_test "p/t 0x01"		" = 1"
+    gdb_test "p/t 0xf0f"	" = 1111 0000 1111"
+    gdb_test "p/t 0x70f"	" = 111 0000 1111"
+    gdb_test_no_output "set print nibbles off"
+}
+
 proc test_print_string_constants {} {
     global gdb_prompt
 
@@ -1067,6 +1080,7 @@  test_print_int_arrays
 test_print_typedef_arrays
 test_artificial_arrays
 test_print_char_arrays
+test_print_nibbles
 # We used to do the runto main here.
 test_print_string_constants
 test_print_array_constants
diff --git a/gdb/valprint.c b/gdb/valprint.c
index c6ea0d82e40..1e79cc73beb 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -108,6 +108,7 @@  struct value_print_options user_print_options =
   0,				/* vtblprint */
   1,				/* unionprint */
   1,				/* addressprint */
+  false,			/* nibblesprint */
   0,				/* objectprint */
   PRINT_MAX_DEFAULT,		/* print_max */
   10,				/* repeat_count_threshold */
@@ -260,6 +261,17 @@  show_unionprint (struct ui_file *file, int from_tty,
 		    value);
 }
 
+/* Controls the format of printing binary values.  */
+
+static void
+show_nibbles (struct ui_file *file, int from_tty,
+		       struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file,
+		    _("Printing binary values in groups is %s.\n"),
+		    value);
+}
+
 /* If nonzero, causes machine addresses to be printed in certain contexts.  */
 
 static void
@@ -1367,7 +1379,8 @@  print_floating (const gdb_byte *valaddr, struct type *type,
 
 void
 print_binary_chars (struct ui_file *stream, const gdb_byte *valaddr,
-		    unsigned len, enum bfd_endian byte_order, bool zero_pad)
+		    unsigned len, enum bfd_endian byte_order, bool zero_pad,
+		    const struct value_print_options *options)
 {
   const gdb_byte *p;
   unsigned int i;
@@ -1390,6 +1403,8 @@  print_binary_chars (struct ui_file *stream, const gdb_byte *valaddr,
 
 	  for (i = 0; i < (HOST_CHAR_BIT * sizeof (*p)); i++)
 	    {
+	      if (options->nibblesprint && seen_a_one && i % 4 == 0)
+		fputc_filtered (' ', stream);
 	      if (*p & (mask >> i))
 		b = '1';
 	      else
@@ -1410,6 +1425,8 @@  print_binary_chars (struct ui_file *stream, const gdb_byte *valaddr,
 	{
 	  for (i = 0; i < (HOST_CHAR_BIT * sizeof (*p)); i++)
 	    {
+	      if (options->nibblesprint && seen_a_one && i % 4 == 0)
+		fputc_filtered (' ', stream);
 	      if (*p & (mask >> i))
 		b = '1';
 	      else
@@ -3016,6 +3033,15 @@  static const gdb::option::option_def value_print_option_defs[] = {
     NULL, /* help_doc */
   },
 
+  boolean_option_def {
+    "nibbles",
+    [] (value_print_options *opt) { return &opt->nibblesprint; },
+    show_nibbles, /* show_cmd_cb */
+    N_("Set whether to print binary values in groups of four bits."),
+    N_("Show whether to print binary values in groups of four bits."),
+    NULL, /* help_doc */
+  },
+
   uinteger_option_def {
     "elements",
     [] (value_print_options *opt) { return &opt->print_max; },
diff --git a/gdb/valprint.h b/gdb/valprint.h
index e1dae2cc8fc..bb19c41ab68 100644
--- a/gdb/valprint.h
+++ b/gdb/valprint.h
@@ -44,6 +44,9 @@  struct value_print_options
   /* Controls printing of addresses.  */
   bool addressprint;
 
+  /* Controls printing of nibbles.  */
+  bool nibblesprint;
+
   /* Controls looking up an object's derived type using what we find
      in its vtables.  */
   bool objectprint;
@@ -149,7 +152,8 @@  extern void value_print_scalar_formatted
    int size, struct ui_file *stream);
 
 extern void print_binary_chars (struct ui_file *, const gdb_byte *,
-				unsigned int, enum bfd_endian, bool);
+				unsigned int, enum bfd_endian, bool,
+				const struct value_print_options *options);
 
 extern void print_octal_chars (struct ui_file *, const gdb_byte *,
 			       unsigned int, enum bfd_endian);