Maamoun TK <maamoun...@googlemail.com> writes:
> Sure. According to Power ISA 2.07:
> The lvsl and lvsr instructions can be used to create the permute control
> vector to be used by a subsequent vperm instruction.
>
> So the lvsl and lvsr instructions check 'sh' value in order to fill the
> vector register, if 'sh' is 0 the vector register will be populated as
> follow
> 0x000102030405060708090A0B0C0D0E0F
> this can be done using the following instructions
> li r9, 0
> lvsl LE_MASK, r9, r9
> Now we xor each byte with 3 using these instructions
> vspltisb LE_TEMP, 0x03
> vxor LE_MASK, LE_MASK, LE_TEMP
> The value of the vector register is now
> 0x03020100070605040B0A09080F0E0D0C
Thanks. I've added some comments about this.
I've also extended the fat setup to check for altivec, using the logic
hwcap = getauxval(AT_HWCAP);
...
/* We also need VSX instructions, mainly for load and store. */
features->have_altivec
= ((hwcap & (PPC_FEATURE_HAS_ALTIVEC | PPC_FEATURE_HAS_VSX))
== (PPC_FEATURE_HAS_ALTIVEC | PPC_FEATURE_HAS_VSX));
For now, gnu/linux only, patches to get detection working also on
freebsd and aix welcome (I think needed fixes will be close to trivial,
but I have no easy way to test, and I don't want to commit untested code).
For non-fat builds, the new code is disabled by default, with a
configure option --enable-power-altivec.
And I've merged the changes to the master branch. I have some work-in
progress code to do 2 or 4 chacha blocks in parallel, but not sure when
I will get that into working shape.
Regards,
/Niels
--
Niels Möller. PGP-encrypted email is preferred. Keyid 368C6677.
Internet email is subject to wholesale government surveillance.
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