[PATCH v2 1/3] include: Add support for byteorder/endianness conversion

[Samuel Holland]

On 2/1/23 22:44, Rahul Pathak wrote:
> Define macros general byteorder conversion
> Define functions for endianness conversion
> from general byteorder conversion macros
> 
> Signed-off-by: Rahul Pathak <rpathak at ventanamicro.com>
> Reviewed-by: Xiang W <wxjstz at 126.com>
> Reviewed-by: Sergey Matyukevich <sergey.matyukevich at syntacore.com>
> ---
>  include/sbi/sbi_byteorder.h | 57 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
>  create mode 100644 include/sbi/sbi_byteorder.h
> 
> diff --git a/include/sbi/sbi_byteorder.h b/include/sbi/sbi_byteorder.h
> new file mode 100644
> index 000000000000..680710fe6d91
> --- /dev/null
> +++ b/include/sbi/sbi_byteorder.h
> @@ -0,0 +1,57 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2023 Ventana Micro Systems Inc.
> + */
> +
> +#ifndef __SBI_BYTEORDER_H__
> +#define __SBI_BYTEORDER_H__
> +
> +#include <sbi/sbi_types.h>
> +
> +#define EXTRACT_BYTE(x, n)	((unsigned long long)((uint8_t *)&x)[n])
> +
> +#define BSWAP16(x)	((EXTRACT_BYTE(x, 0) << 8) | EXTRACT_BYTE(x, 1))
> +#define BSWAP32(x)	((EXTRACT_BYTE(x, 0) << 24) | (EXTRACT_BYTE(x, 1) << 16) | \
> +			 (EXTRACT_BYTE(x, 2) << 8) | EXTRACT_BYTE(x, 3))
> +#define BSWAP64(x)	((EXTRACT_BYTE(x, 0) << 56) | (EXTRACT_BYTE(x, 1) << 48) | \
> +			 (EXTRACT_BYTE(x, 2) << 40) | (EXTRACT_BYTE(x, 3) << 32) | \
> +			 (EXTRACT_BYTE(x, 4) << 24) | (EXTRACT_BYTE(x, 5) << 16) | \
> +			 (EXTRACT_BYTE(x, 6) << 8) | EXTRACT_BYTE(x, 7))

This implementation is wrong. It only does any swapping on little-endian
systems. That was the desired behavior for CPU_TO_FDT*, but these macros
need to swap bytes regardless of the native endianness.

(Somehow, none of the other three reviewers noticed this?)

Regards,
Samuel

> +#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__  /* CPU(little-endian) */
> +#define cpu_to_be16(x)		((uint16_t)BSWAP16(x))
> +#define cpu_to_be32(x)		((uint32_t)BSWAP32(x))
> +#define cpu_to_be64(x)		((uint64_t)BSWAP64(x))
> +
> +#define be16_to_cpu(x)		((uint16_t)BSWAP16(x))
> +#define be32_to_cpu(x)		((uint32_t)BSWAP32(x))
> +#define be64_to_cpu(x)		((uint64_t)BSWAP64(x))
> +
> +#define cpu_to_le16(x)		((uint16_t)(x))
> +#define cpu_to_le32(x)		((uint32_t)(x))
> +#define cpu_to_le64(x)		((uint64_t)(x))
> +
> +#define le16_to_cpu(x)		((uint16_t)(x))
> +#define le32_to_cpu(x)		((uint32_t)(x))
> +#define le64_to_cpu(x)		((uint64_t)(x))
> +#else /* CPU(big-endian) */
> +#define cpu_to_be16(x)		((uint16_t)(x))
> +#define cpu_to_be32(x)		((uint32_t)(x))
> +#define cpu_to_be64(x)		((uint64_t)(x))
> +
> +#define be16_to_cpu(x)		((uint16_t)(x))
> +#define be32_to_cpu(x)		((uint32_t)(x))
> +#define be64_to_cpu(x)		((uint64_t)(x))
> +
> +#define cpu_to_le16(x)		((uint16_t)BSWAP16(x))
> +#define cpu_to_le32(x)		((uint32_t)BSWAP32(x))
> +#define cpu_to_le64(x)		((uint64_t)BSWAP64(x))
> +
> +#define le16_to_cpu(x)		((uint16_t)BSWAP16(x))
> +#define le32_to_cpu(x)		((uint32_t)BSWAP32(x))
> +#define le64_to_cpu(x)		((uint64_t)BSWAP64(x))
> +#endif
> +
> +#endif /* __SBI_BYTEORDER_H__ */