[Pixman] [PATCH 5/6] mmx: introduce is_equal and is_zero functions

[Søren Sandmann]

Matt Turner <mattst88 at gmail.com> writes:

> To be used by the next commit.
>
> Signed-off-by: Matt Turner <mattst88 at gmail.com>
> ---
>  pixman/pixman-mmx.c |   17 +++++++++++++++++
>  1 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/pixman/pixman-mmx.c b/pixman/pixman-mmx.c
> index 8b55b32..63edf18 100644
> --- a/pixman/pixman-mmx.c
> +++ b/pixman/pixman-mmx.c
> @@ -416,6 +416,23 @@ store8888 (uint32_t *dest, __m64 v)
>      store(dest, v);
>  }
>  
> +static force_inline pixman_bool_t
> +is_equal (__m64 a, __m64 b)
> +{
> +#ifdef USE_LOONGSON_MMI
> +    /* __m64 is double, we can compare directly. */
> +    return a == b;
> +#else
> +    return to_uint64 (a) == to_uint64 (b);
> +#endif
> +}

This looks like it will be somewhat less efficient on x86 and possibly
iwmmxt, because it will result in a and b being converted from mmx to 64
bit integers before comparing.

A better way probably be to do something along the lines of what the SSE
implementation does and introduce is_opaque() and is_zero() functions
that use pcmpeqw and pmovmskb.

The pmovmskb instruction is part of the MMX extended instruction set, so
it can be handled similarly to pshufw and pmulhuw.


Soren