On Tue, Nov 18, 2014 at 09:56:09PM +0100, Mariusz Gorski wrote:
> Avoid values comparison and use a macro instead that checks
> whether module param has been set by the user to some value
> at loading time.
>
> Signed-off-by: Mariusz Gorski <marius.gorski@xxxxxxxxx>
> ---
> drivers/staging/panel/panel.c | 88 ++++++++++++++++++++++---------------------
> 1 file changed, 45 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
> index 1b4a211..97fc4ca 100644
> --- a/drivers/staging/panel/panel.c
> +++ b/drivers/staging/panel/panel.c
> @@ -135,6 +135,8 @@
>
> #define NOT_SET -1
>
> +#define IS_NOT_SET(x) (x == NOT_SET)
> +
> /* macros to simplify use of the parallel port */
> #define r_ctr(x) (parport_read_control((x)->port))
> #define r_dtr(x) (parport_read_data((x)->port))
> @@ -1411,29 +1413,29 @@ static void lcd_init(void)
> switch (lcd_type) {
> case LCD_TYPE_OLD:
> /* parallel mode, 8 bits */
> - if (lcd_proto < 0)
> + if (IS_NOT_SET(lcd_proto))
> lcd_proto = LCD_PROTO_PARALLEL;
> - if (lcd_charset < 0)
> + if (IS_NOT_SET(lcd_charset))
> lcd_charset = LCD_CHARSET_NORMAL;
> if (lcd_e_pin == PIN_NOT_SET)
> lcd_e_pin = PIN_STROBE;
> if (lcd_rs_pin == PIN_NOT_SET)
> lcd_rs_pin = PIN_AUTOLF;
>
> - if (lcd_width < 0)
> + if (IS_NOT_SET(lcd_width))
> lcd_width = 40;
(...)
I'm not convinced at all by the increased readability of this one.
To me it adds obfuscation since I have to look for the macro definition
to see how it checks whether the type is set or not.
I think you'd rather simply open-code the macro here and keep the natural
comparison. The fields were already initialized to the NOT_SET value, better
check agaist the same value here especially since it matches other tests as
well. That would give :
- if (lcd_proto < 0)
+ if (lcd_proto == NOT_SET)
lcd_proto = LCD_PROTO_PARALLEL;
etc... To me it's more readable.
Willy
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