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Date:   Mon, 5 Dec 2022 10:17:45 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Cc:     linux-renesas-soc@vger.kernel.org,
        Kieran Bingham <kieran.bingham@ideasonboard.com>
Subject: Re: [PATCH kms++ v2 3/4] kms++util: Add endian.h
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Hi Tomi,

Thank you for the patch.

On Mon, Dec 05, 2022 at 10:03:38AM +0200, Tomi Valkeinen wrote:
> Add simple endianness supporting write function, and, for now, only one
> shortcut helper, write16le().
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  kms++util/inc/kms++util/endian.h | 46 ++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
>  create mode 100644 kms++util/inc/kms++util/endian.h
> 
> diff --git a/kms++util/inc/kms++util/endian.h b/kms++util/inc/kms++util/endian.h
> new file mode 100644
> index 0000000..0f7aecd
> --- /dev/null
> +++ b/kms++util/inc/kms++util/endian.h
> @@ -0,0 +1,46 @@
> +#pragma once
> +
> +#include <type_traits>
> +#include <byteswap.h>
> +#include <stdint.h>
> +
> +static_assert((__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) ||
> +	      (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__),
> +	      "Unable to detect endianness");
> +
> +enum class endian {
> +	little = __ORDER_LITTLE_ENDIAN__,
> +	big = __ORDER_BIG_ENDIAN__,
> +	native = __BYTE_ORDER__
> +};
> +
> +template<typename T>
> +constexpr T byteswap(T value) noexcept
> +{
> +	static_assert(std::is_integral<T>(), "Type is not integral");
> +	static_assert(sizeof(T) == 2 ||
> +		      sizeof(T) == 4 ||
> +		      sizeof(T) == 8,
> +		      "Illegal value size");
> +
> +	switch (sizeof(T)) {
> +		case 2: return bswap_16(value);
> +		case 4: return bswap_32(value);
> +		case 8: return bswap_64(value);
> +	}
> +}
> +
> +template<endian E, typename T>
> +static void write_endian(T* dst, T val)
> +{
> +	if constexpr (E != endian::native)
> +		val = byteswap(val);
> +
> +	*dst = val;
> +}
> +
> +[[maybe_unused]]
> +static void write16le(uint16_t* dst, uint16_t val)
> +{
> +	write_endian<endian::little, uint16_t>(dst, val);
> +}

-- 
Regards,

Laurent Pinchart