linux-kernel - Re: [PATCH v1 1/6] tiocl.h: Change/Add defines for mouse report

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Message-ID: <f00141ec-5da4-2743-7064-8094d7915f7c@kernel.org>
Date:   Tue, 30 Jun 2020 09:55:27 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Tammo Block <tammo.block@...il.com>, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v1 1/6] tiocl.h: Change/Add defines for mouse report

On 30. 06. 20, 9:10, Tammo Block wrote:
> Add additional defines for mouse event types. The change of the value
> of TIOCL_SELBUTTONMASK deserves a bit more explanation :
> 
> The old value of 15 uses the first 4 bits and sends them unchanged back
> to userspace if requested by an application. But in fact only the first
> two bits have ever been used by any daemon or useful at all, as the
> kernel already knows the status of the shift and alt keys encoded in
> bits 3 and 4. On the other hand we *do* want to know the status of bits
> 6-8, encoding button values >3 and mouse move and drag operations.
> 
> This change is up- and downwards compatible by masking all spourious
> bits and leaving only the undisputed parts (bits 1 and 2) untouched.
> 
> Signed-off-by: Tammo Block <tammo.block@...il.com>
> ---
>  include/uapi/linux/tiocl.h | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/tiocl.h b/include/uapi/linux/tiocl.h
> index b32acc229024..c862053041e4 100644
> --- a/include/uapi/linux/tiocl.h
> +++ b/include/uapi/linux/tiocl.h
> @@ -9,7 +9,7 @@
>  #define 	TIOCL_SELPOINTER	3	/* show the pointer */
>  #define 	TIOCL_SELCLEAR	4	/* clear visibility of selection */
>  #define 	TIOCL_SELMOUSEREPORT	16	/* report beginning of selection */
> -#define 	TIOCL_SELBUTTONMASK	15	/* button mask for report */
> +#define 	TIOCL_SELBUTTONMASK	227	/* button mask for report */

0xe3 is more obvious (can be in-brain translated to bits).

If C only had 0b prefix like perl has...

>  /* selection extent */
>  struct tiocl_selection {
>  	unsigned short xs;	/* X start */
> @@ -28,7 +28,11 @@ struct tiocl_selection {
>  
>  /* these two don't return a value: they write it back in the type */
>  #define TIOCL_GETSHIFTSTATE	6	/* write shift state */
> -#define TIOCL_GETMOUSEREPORTING	7	/* write whether mouse event are reported */
> +#define TIOCL_GETMOUSEREPORTING	7	/* write which mouse event are reported */

s/event/&s/

> +#define		TIOCL_REPORTBTNPRESS	1	/* report button press only    "9" */
> +#define		TIOCL_REPORTRELEASE	2	/* report press and release "1000" */
> +#define		TIOCL_REPORTDRAG	3	/* report drag events       "1002" */
> +#define		TIOCL_REPORTANYMOVE	4	/* report any movement      "1003" */
>  #define TIOCL_SETVESABLANK	10	/* set vesa blanking mode */
>  #define TIOCL_SETKMSGREDIRECT	11	/* restrict kernel messages to a vt */
>  #define TIOCL_GETFGCONSOLE	12	/* get foreground vt */
> 

thanks,
-- 
js
suse labs