On 03/12/2022 01:56, Laurent Pinchart wrote:
Hi Tomi, Thank you for the patch. On Fri, Dec 02, 2022 at 03:16:57PM +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@xxxxxxxxxxxxxxxx> --- 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..ea09065 --- /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 val, T* dst)I would have swapped the parameters, common APIs have the destination first and the source second. Same below, and up to you.
True, I think that makes sense.
+{ + if constexpr (E != endian::native) + val = byteswap(val); + + *dst = val; +} + +[[maybe_unused]] +static void write16le(uint16_t val, uint16_t* dst)I wonder if writing using write16le = write_endian<endian::little, uint16_t>; would compile.
No, using needs a type. Tomi
