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[PATCH 1/2] Staging:iio:Prefer using BIT macro

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  [PATCH 1/2] Staging:iio:Prefer using BIT macro Bhumika Goyal <bhumirks@gmail.com> - 2016-02-08 08:00 +0100
    Re: [PATCH 1/2] Staging:iio:Prefer using BIT macro Lars-Peter Clausen <lars@metafoo.de> - 2016-02-08 10:20 +0100
      Re: [PATCH 1/2] Staging:iio:Prefer using BIT macro Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-02-08 16:20 +0100

#1328798 — [PATCH 1/2] Staging:iio:Prefer using BIT macro

This patch replaces bit shifting on 1 with the BIT(x) macro.
This was done with coccinelle:
 @@ int g; @@
-(1 << g)
+BIT(g)

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
---
 drivers/staging/iio/adc/ad7816.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7816.c
index 2226051..f631012 100644
--- a/drivers/staging/iio/adc/ad7816.c
+++ b/drivers/staging/iio/adc/ad7816.c
@@ -222,7 +222,7 @@ static ssize_t ad7816_show_value(struct device *dev,
 		value = (s8)((data >> AD7816_TEMP_FLOAT_OFFSET) - 103);
 		data &= AD7816_TEMP_FLOAT_MASK;
 		if (value < 0)
-			data = (1 << AD7816_TEMP_FLOAT_OFFSET) - data;
+			data = BIT(AD7816_TEMP_FLOAT_OFFSET) - data;
 		return sprintf(buf, "%d.%.2d\n", value, data * 25);
 	}
 	return sprintf(buf, "%u\n", data);
-- 
1.9.1

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#1328843

On 02/08/2016 07:48 AM, Bhumika Goyal wrote:
> This patch replaces bit shifting on 1 with the BIT(x) macro.
> This was done with coccinelle:
>  @@ int g; @@
> -(1 << g)
> +BIT(g)
> 
> Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>

Hi,

Thanks for the patch.

> ---
>  drivers/staging/iio/adc/ad7816.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7816.c
> index 2226051..f631012 100644
> --- a/drivers/staging/iio/adc/ad7816.c
> +++ b/drivers/staging/iio/adc/ad7816.c
> @@ -222,7 +222,7 @@ static ssize_t ad7816_show_value(struct device *dev,
>  		value = (s8)((data >> AD7816_TEMP_FLOAT_OFFSET) - 103);
>  		data &= AD7816_TEMP_FLOAT_MASK;
>  		if (value < 0)
> -			data = (1 << AD7816_TEMP_FLOAT_OFFSET) - data;
> +			data = BIT(AD7816_TEMP_FLOAT_OFFSET) - data;


But in this case this is a false positive. The intended semantic meaning
here is 2**... not BIT(...). Using BIT() here in my opinion only causes
confusion.

>  		return sprintf(buf, "%d.%.2d\n", value, data * 25);
>  	}
>  	return sprintf(buf, "%u\n", data);
> 

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#1329169

On Mon, Feb 8, 2016 at 11:14 AM, Lars-Peter Clausen <lars@metafoo.de> wrote:
> On 02/08/2016 07:48 AM, Bhumika Goyal wrote:

>>               value = (s8)((data >> AD7816_TEMP_FLOAT_OFFSET) - 103);
>>               data &= AD7816_TEMP_FLOAT_MASK;
>>               if (value < 0)
>> -                     data = (1 << AD7816_TEMP_FLOAT_OFFSET) - data;
>> +                     data = BIT(AD7816_TEMP_FLOAT_OFFSET) - data;
>
>
> But in this case this is a false positive. The intended semantic meaning
> here is 2**... not BIT(...). Using BIT() here in my opinion only causes
> confusion.

+1. Here clearly the intention is to change sign of the value which
fits less than 32/16/8 bits. 1 << OFFSET represents '-0'.

-- 
With Best Regards,
Andy Shevchenko

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