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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
In-reply-to: <1474048017-26696-6-git-send-email-rth@twiddle.net>
Date: Tue, 04 Oct 2016 09:46:12 +0100
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Subject: Re: [Qemu-devel] [PATCH v4 05/35] int128: Add int128_make128
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To: Richard Henderson <rth@twiddle.net>
Cc: qemu-devel@nongnu.org


Richard Henderson <rth@twiddle.net> writes:

> Allows Int128 to be used more generally, rather than having to
> begin with 64-bit inputs and accumulate.
>
> Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  include/qemu/int128.h | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/include/qemu/int128.h b/include/qemu/int128.h
> index 08f1db1..67440fa 100644
> --- a/include/qemu/int128.h
> +++ b/include/qemu/int128.h
> @@ -10,6 +10,11 @@ static inline Int128 int128_make64(uint64_t a)
>      return a;
>  }
>
> +static inline Int128 int128_make128(uint64_t lo, uint64_t hi)
> +{
> +    return (unsigned __int128)hi << 64 | lo;
> +}
> +
>  static inline uint64_t int128_get64(Int128 a)
>  {
>      uint64_t r = a;
> @@ -146,6 +151,11 @@ static inline Int128 int128_make64(uint64_t a)
>      return (Int128) { a, 0 };
>  }
>
> +static inline Int128 int128_make128(uint64_t lo, uint64_t hi)
> +{
> +    return (Int128) { lo, hi };
> +}
> +
>  static inline uint64_t int128_get64(Int128 a)
>  {
>      assert(!a.hi);
> @@ -195,9 +205,9 @@ static inline Int128 int128_rshift(Int128 a, int n)
>      }
>      h = a.hi >> (n & 63);
>      if (n >= 64) {
> -        return (Int128) { h, h >> 63 };
> +        return int128_make128(h, h >> 63);
>      } else {
> -        return (Int128) { (a.lo >> n) | ((uint64_t)a.hi << (64 - n)), h };
> +        return int128_make128((a.lo >> n) | ((uint64_t)a.hi << (64 - n)), h);
>      }
>  }
>
> @@ -211,18 +221,18 @@ static inline Int128 int128_add(Int128 a, Int128 b)
>       *
>       * So the carry is lo < a.lo.
>       */
> -    return (Int128) { lo, (uint64_t)a.hi + b.hi + (lo < a.lo) };
> +    return int128_make128(lo, (uint64_t)a.hi + b.hi + (lo < a.lo));
>  }
>
>  static inline Int128 int128_neg(Int128 a)
>  {
>      uint64_t lo = -a.lo;
> -    return (Int128) { lo, ~(uint64_t)a.hi + !lo };
> +    return int128_make128(lo, ~(uint64_t)a.hi + !lo);
>  }
>
>  static inline Int128 int128_sub(Int128 a, Int128 b)
>  {
> -    return (Int128){ a.lo - b.lo, (uint64_t)a.hi - b.hi - (a.lo < b.lo) };
> +    return int128_make128(a.lo - b.lo, (uint64_t)a.hi - b.hi - (a.lo < b.lo));
>  }
>
>  static inline bool int128_nonneg(Int128 a)


--
Alex Bennée