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Re: [PATCH v3 05/19] crypto: Add generic 16-bit carry-less multiply rout
From: |
Ard Biesheuvel |
Subject: |
Re: [PATCH v3 05/19] crypto: Add generic 16-bit carry-less multiply routines |
Date: |
Sun, 10 Sep 2023 14:28:08 +0200 |
On Mon, 21 Aug 2023 at 18:19, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> include/crypto/clmul.h | 16 ++++++++++++++++
> crypto/clmul.c | 21 +++++++++++++++++++++
> 2 files changed, 37 insertions(+)
>
> diff --git a/include/crypto/clmul.h b/include/crypto/clmul.h
> index 153b5e3057..c7ad28aa85 100644
> --- a/include/crypto/clmul.h
> +++ b/include/crypto/clmul.h
> @@ -38,4 +38,20 @@ uint64_t clmul_8x4_odd(uint64_t, uint64_t);
> */
> uint64_t clmul_8x4_packed(uint32_t, uint32_t);
>
> +/**
> + * clmul_16x2_even:
> + *
> + * Perform two 16x16->32 carry-less multiplies.
> + * The odd words of the inputs are ignored.
> + */
> +uint64_t clmul_16x2_even(uint64_t, uint64_t);
> +
> +/**
> + * clmul_16x2_odd:
> + *
> + * Perform two 16x16->32 carry-less multiplies.
> + * The even bytes of the inputs are ignored.
even words
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
> + */
> +uint64_t clmul_16x2_odd(uint64_t, uint64_t);
> +
> #endif /* CRYPTO_CLMUL_H */
> diff --git a/crypto/clmul.c b/crypto/clmul.c
> index 82d873fee5..2c87cfbf8a 100644
> --- a/crypto/clmul.c
> +++ b/crypto/clmul.c
> @@ -58,3 +58,24 @@ uint64_t clmul_8x4_packed(uint32_t n, uint32_t m)
> {
> return clmul_8x4_even_int(unpack_8_to_16(n), unpack_8_to_16(m));
> }
> +
> +uint64_t clmul_16x2_even(uint64_t n, uint64_t m)
> +{
> + uint64_t r = 0;
> +
> + n &= 0x0000ffff0000ffffull;
> + m &= 0x0000ffff0000ffffull;
> +
> + for (int i = 0; i < 16; ++i) {
> + uint64_t mask = (n & 0x0000000100000001ull) * 0xffffffffull;
> + r ^= m & mask;
> + n >>= 1;
> + m <<= 1;
> + }
> + return r;
> +}
> +
> +uint64_t clmul_16x2_odd(uint64_t n, uint64_t m)
> +{
> + return clmul_16x2_even(n >> 16, m >> 16);
> +}
> --
> 2.34.1
>
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Ard Biesheuvel <=