Whole-known-network
<p><span class="h-card" translate="no"><a href="https://tech.lgbt/@snowfox" class="u-url mention">@<span>snowfox</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> That gets you up to 128 entries with linearly increasing cost.</p><p>(The idea is that the lower table inds roll into negatives, so the later VPSHUFB give all 0.)</p><p>You can do the same with a tree of VPBLENDVB, but this needs fewer temp regs and is somewhat easier to set up into.</p><p>You can also do up to 256 by using VPSUBSB (so that you saturate at -128), doing one 128-entry LUT for [0:128] and one for [128:256] with index^128 as seed, and a final VPBLENDVB to combine.</p>
<p><span class="h-card" translate="no"><a href="https://mastodon.social/@unspeaker" class="u-url mention">@<span>unspeaker</span></a></span> <span class="h-card" translate="no"><a href="https://unstable.systems/@demize" class="u-url mention">@<span>demize</span></a></span> <span class="h-card" translate="no"><a href="https://social.noyu.me/@hikari" class="u-url mention">@<span>hikari</span></a></span> an individual is simply an abstraction in the domain of application of power. it is not something inherent to our existence</p>
<p><span class="h-card" translate="no"><a href="https://mastodon.gamedev.place/@rygorous" class="u-url mention">@<span>rygorous</span></a></span> <span class="h-card" translate="no"><a href="https://tech.lgbt/@snowfox" class="u-url mention">@<span>snowfox</span></a></span> oh perfect, this is exactly what i was wondering about!</p>
<p><span class="h-card" translate="no"><a href="https://tech.lgbt/@snowfox" class="u-url mention">@<span>snowfox</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> Since PSHUFB returns 0 when the MSB is set, you can chain them with XORs to get larger LUTs (in 16B increments) if you're OK with the LUT itself being a bit funny. Specifically:</p><p> vpshufb out, lut0, index</p><p> vpsubb index, index, sixteen<br /> vpshufb temp, lut1, index<br /> vpxor out, out, temp</p><p> vpsubb index, index, sixteen<br /> vpshufb temp, lut2, index<br /> vpxor out, out, temp</p><p>init:<br /> lut0 = tab[0:16]<br /> lut1 = tab[16:32] ^ lut0<br /> lut2 = tab[32:48] ^ lut1</p><p>and so forth</p>
<p><span class="h-card" translate="no"><a href="https://mastodon.gamedev.place/@rygorous" class="u-url mention">@<span>rygorous</span></a></span> thanks!</p>
<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> For tables in immediate operands, the main ones are AVX512+.</p><p>VPTERNLOGD has a 8-bit truth table of its 3 inputs as imm8.</p><p>VFIXUPIMM[SP][DS] has a 32-bit LUT embedded as imm32 that says how to treat various float special values</p><p>There's a weird secondary opcode byte (not really a LUT) as imm8 for PCMP[EI]STR[IM] (SSE4.2).</p>
<p><span class="h-card" translate="no"><a href="https://mastodon.social/@whitequark" class="u-url mention">@<span>whitequark</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.social/@dougall" class="u-url mention">@<span>dougall</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.gamedev.place/@rygorous" class="u-url mention">@<span>rygorous</span></a></span> Yes, ternlogop and fixup are the main ones. There were a few other fixup-like instructions added later I think?</p>
<p>Now I know how my elders felt about the fact that my fellow millennials and I never answered the phone.</p>
<p>Part of the boomer effect with respect to technology comes from shifts in what's considered basic communication infrastructure over time. For my generation it's email and SMS. For an older generation it was phone calls and letters. I've been putting more effort into getting to know people in my area recently, and it is *so* painful: everything is Instagram, Discord, and Twitter (yes really, Twitter, still!). I feel like a dinosaur. Most people wont even respond to emails.</p>