[libcamera-devel] [PATCH v3 1/8] libcamera: utils: Define BIT() macro

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Wed, Apr 03, 2019 at 05:07:28PM +0200, Jacopo Mondi wrote:
> Define BIT(b_) macro which expands to a left bit shift.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/include/utils.h | 1 +
>  src/libcamera/utils.cpp       | 5 +++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
> index 79038a96feab..1a6cf7f7b9dc 100644
> --- a/src/libcamera/include/utils.h
> +++ b/src/libcamera/include/utils.h
> @@ -10,6 +10,7 @@
>  #include <memory>
>  
>  #define ARRAY_SIZE(a)	(sizeof(a) / sizeof(a[0]))
> +#define BIT(b_)		(1 << (b_))

I'm curious, why the _ ? I'm also curious, why do you think we need this
macro ? :-) Usage of BIT() in the Linux kernel is partly to fix problems
with (1 << 31) on 32-bit platforms, with BIT() defined as (1UL << (nr)).

>  
>  namespace libcamera {
>  
> diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
> index cd0fd7614cc7..1a5a2a03b1ca 100644
> --- a/src/libcamera/utils.cpp
> +++ b/src/libcamera/utils.cpp
> @@ -24,6 +24,11 @@ namespace utils {
>   * \brief Determine the number of elements in the static array.
>   */
>  
> +/**
> + * \def BIT(b)
> + * \brief Bitwise left shift by \a b bits

Bitwise left shift of what ? :-)

> + */
> +
>  /**
>   * \brief Strip the directory prefix from the path
>   * \param[in] path The path to process

-- 
Regards,

Laurent Pinchart