[PATCH v6 1/2] gdb: Add new 'print nibbles' feature

[PATCH v6 1/2] gdb: Add new 'print nibbles' feature

[Enze Li]

New in v6:
- Address Eli's comments. Use a new complementary method
  with the number 0.

New in v5:
- Address Bruno's comments. Fix regressions caused by code
  conflicts.

Make an introduction of a new print setting that can be set
by 'set print nibbles [on|off]'.  The default value is OFF,
which can be changed by users manually.

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

This new feature displays binary values by group, with four
bits per group.

The motivation behind this work is to enhance the readability
of binary values.

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 = 0100 1100 1110

Tested on x86_64-linux(little-endian) and mips-linux(big-endian).
---
 gdb/printcmd.c                       |  2 +-
 gdb/testsuite/gdb.base/options.exp   |  1 +
 gdb/testsuite/gdb.base/printcmds.exp | 14 +++++++++
 gdb/valprint.c                       | 44 +++++++++++++++++++++++++++-
 gdb/valprint.h                       |  6 +++-
 5 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index e408b19db63..ef1a80ecae3 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..aebbe00bc7b 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"		" = 0011 0000"
+    gdb_test "p/t 0xff"		" = 1111 1111"
+    gdb_test "p/t 0x0f"		" = 1111"
+    gdb_test "p/t 0x01"		" = 0001"
+    gdb_test "p/t 0xf0f"	" = 1111 0000 1111"
+    gdb_test "p/t 0x70f"	" = 0111 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 4230dcec228..9b4a836b9b7 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 +1403,9 @@ 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
@@ -1397,6 +1413,13 @@ print_binary_chars (struct ui_file *stream, const gdb_byte *valaddr,
 
 	      if (zero_pad || seen_a_one || b == '1')
 		fputc_filtered (b, stream);
+	      else if (options->nibblesprint)
+		{
+		  if ((0xf0 & (mask >> i) && (*p & 0xf0)) ||
+		      (0x0f & (mask >> i) && (*p & 0x0f)))
+		    fputc_filtered (b, stream);
+		}
+
 	      if (b == '1')
 		seen_a_one = true;
 	    }
@@ -1410,6 +1433,9 @@ 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
@@ -1417,6 +1443,13 @@ print_binary_chars (struct ui_file *stream, const gdb_byte *valaddr,
 
 	      if (zero_pad || seen_a_one || b == '1')
 		fputc_filtered (b, stream);
+	      else if (options->nibblesprint)
+		{
+		  if ((0xf0 & (mask >> i) && (*p & 0xf0)) ||
+		      (0x0f & (mask >> i) && (*p & 0x0f)))
+		    fputc_filtered (b, stream);
+		}
+
 	      if (b == '1')
 		seen_a_one = true;
 	    }
@@ -3016,6 +3049,15 @@ 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);
-- 
2.34.1

[PATCH v6 2/2] gdb/doc: Document "print nibbles"

[Enze Li]

* gdb/doc/gdb.texinfo: (Print Settings): Document 'print nibbles'.
* NEWS: Metion new command.
---
 gdb/NEWS            |  5 +++++
 gdb/doc/gdb.texinfo | 35 +++++++++++++++++++++++++++++++----
 2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 13b66286876..b09f87ac730 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -231,6 +231,11 @@ 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 d0c5bcf18e1..e78df4e605e 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -2140,10 +2140,10 @@ on @code{-} after the command name.  For example:
 
 @smallexample
 (@value{GDBP}) print -@key{TAB}@key{TAB}
--address         -max-depth               -pretty          -symbol
--array           -memory-tag-violations   -raw-values      -union
--array-indexes   -null-stop               -repeats         -vtbl
--elements        -object                  -static-members
+-address         -max-depth               -object          -static-members
+-array           -memory-tag-violations   -pretty          -symbol
+-array-indexes   -nibbles                 -raw-values      -union
+-elements        -null-stop               -repeats         -vtbl
 @end smallexample
 
 Completion will in some cases guide you with a suggestion of what kind
@@ -10005,6 +10005,10 @@ 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 -memory-tag-violations [@code{on}|@code{off}]
 Set printing of additional information about memory tag violations.
 @xref{set print memory-tag-violations}.
@@ -11367,6 +11371,29 @@ 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 = 0100 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
-- 
2.34.1

Re: [PATCH v6 2/2] gdb/doc: Document "print nibbles"

[Eli Zaretskii]

> Date: Sat, 11 Dec 2021 19:08:45 +0800
> From: Enze Li via Gdb-patches <gdb-patches@sourceware.org>
> 
> +@item -nibbles [@code{on}|@code{off}]
> +Set whether to print binary values in groups of four bits, known
> +as ``nibbles''. @xref{set print nibbles}.
                 ^^
Two spaces here, please.

The documentation patch is okay with the above nit fixed.

Thanks.

Re: [PATCH v6 1/2] gdb: Add new 'print nibbles' feature

[Bruno Larsen]

On 12/11/21 08:08, Enze Li via Gdb-patches wrote:
> New in v6:
> - Address Eli's comments. Use a new complementary method
>    with the number 0.
> 
> New in v5:
> - Address Bruno's comments. Fix regressions caused by code
>    conflicts.
> 
> Make an introduction of a new print setting that can be set
> by 'set print nibbles [on|off]'.  The default value is OFF,
> which can be changed by users manually.
> 
> Of course, 'show print nibbles' is also included in the patch.
> 
> This new feature displays binary values by group, with four
> bits per group.
> 
> The motivation behind this work is to enhance the readability
> of binary values.
> 
> 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 = 0100 1100 1110
> 
> Tested on x86_64-linux(little-endian) and mips-linux(big-endian).
> ---
>   gdb/printcmd.c                       |  2 +-
>   gdb/testsuite/gdb.base/options.exp   |  1 +
>   gdb/testsuite/gdb.base/printcmds.exp | 14 +++++++++
>   gdb/valprint.c                       | 44 +++++++++++++++++++++++++++-
>   gdb/valprint.h                       |  6 +++-
>   5 files changed, 64 insertions(+), 3 deletions(-)

I don't have the power to tell you to push this commit, but for what it's worth, LGTM now

-- 
Cheers!
Bruno Larsen

Re: [PATCH v6 2/2] gdb/doc: Document "print nibbles"

[Enze Li]

Hi Eli,

Thank you very much for your patience in reviewing this patch.:-)
I'll fix this issue in v7.

Cheers!
Enze

On Sat, 2021-12-11 at 06:43 -0500, Eli Zaretskii wrote:
> > Date: Sat, 11 Dec 2021 19:08:45 +0800
> > From: Enze Li via Gdb-patches <gdb-patches@sourceware.org>
> > 
> > +@item -nibbles [@code{on}|@code{off}]
> > +Set whether to print binary values in groups of four bits, known
> > +as ``nibbles''. @xref{set print nibbles}.
>                  ^^
> Two spaces here, please.
> 
> The documentation patch is okay with the above nit fixed.
> 
> Thanks.

Re: [PATCH v6 1/2] gdb: Add new 'print nibbles' feature

[Enze Li]

On Mon, 2021-12-13 at 12:16 -0300, Bruno Larsen via Gdb-patches wrote:
> On 12/11/21 08:08, Enze Li via Gdb-patches wrote:
> > New in v6:
> > - Address Eli's comments. Use a new complementary method
> >    with the number 0.
> > 
> > New in v5:
> > - Address Bruno's comments. Fix regressions caused by code
> >    conflicts.
> > 
> > Make an introduction of a new print setting that can be set
> > by 'set print nibbles [on|off]'.  The default value is OFF,
> > which can be changed by users manually.
> 
> I don't have the power to tell you to push this commit, but for what
> it's worth, LGTM now
> 

Hi Bruno,

Thank you for your attention. I will continue to improve this patch
sets.

Cheers!
Enze