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<blockquote style="position: relative; padding-left: 55px;"><section><a href="https://mastodon.gamedev.place/users/rygorous/statuses/114586526531387360">Fabian Giesen (rygorous@mastodon.gamedev.place)'s status on Thursday, 29-May-2025 03:16:57 JST</a><a href="https://mastodon.gamedev.place/@rygorous" title="rygorous@mastodon.gamedev.place"><img src="https://gnusocial.jp/avatar/95257-48-20250601185436.webp" width="48" height="48" alt="Fabian Giesen" style="position: absolute; left: 0; top: 0;">Fabian Giesen</a><div><a href="https://mastodon.gamedev.place/@rygorous/114586506498648473" rel="in-reply-to">in reply to</a><ul><li><li><a href="https://gnusocial.jp/user/114870" title="regehr@mastodon.social">John Regehr</a></li><li><a href="https://gnusocial.jp/user/285059" title="resistor@mastodon.online">Owen Anderson</a></li></ul></div></section><article><p><a href="https://mastodon.social/@regehr">@regehr</a> <a href="https://mastodon.online/@resistor">@resistor</a> <a href="https://mastodon.social/@barrelshifter">@barrelshifter</a> For some examples:<br>- PPC and ARM A64 very visibly go for the rotate+mask approach. PPC does everything with rot left + mask (see e.g. <a href="https://devblogs.microsoft.com/oldnewthing/20180810-00/?p=99465" rel="nofollow noreferrer">https://devblogs.microsoft.com/oldnewthing/20180810-00/?p=99465</a>), A64 is rot right + mask (<a href="https://www.scs.stanford.edu/~zyedidia/arm64/ubfm.html" rel="nofollow noreferrer">https://www.scs.stanford.edu/~zyedidia/arm64/ubfm.html</a>), and the A64 logic immediates use basically the same mask generation logic. (So it can be shared if desired, in a small design.)<br>- I have seen datapath details for some Intel designs that used funnel shift right for all usual shifts.</p></article><footer><a rel="bookmark" href="https://gnusocial.jp/conversation/5115999#notice-10035031">In conversation</a><time datetime="2025-05-29T03:16:57+09:00" title="Thursday, 29-May-2025 03:16:57 JST">about 14 days ago</time> <span>from <span><a href="https://gnusocial.jp/notice/10035031" rel="external" title="Sent from gnusocial.jp via ActivityPub">gnusocial.jp</a></span></span><a href="https://gnusocial.jp/notice/10035031">permalink</a><h4>Attachments</h4><ol><li><article><header><div>Domain not in remote thumbnail source whitelist: devblogs.microsoft.com</div><h5><a href="https://devblogs.microsoft.com/oldnewthing/20180810-00/?p=99465">The PowerPC 600 series, part 5: Rotates and shifts - The Old New Thing</a></h5><div> from <span>Raymond Chen</span></div></header><div>Get out your Swiss army knife.</div><footer></footer></article></li><li><article><header><div>No result found on File_thumbnail lookup.</div><h5><a href="https://www.scs.stanford.edu/~zyedidia/arm64/ubfm.html">UBFM -- A64</a></h5><div></div></header><div></div><footer></footer></article></li></ol></footer></blockquote>

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Fabian Giesen (rygorous@mastodon.gamedev.place)'s status on Thursday, 29-May-2025 03:16:57 JSTFabian Giesen
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@regehr @resistor @barrelshifter For some examples:
- PPC and ARM A64 very visibly go for the rotate+mask approach. PPC does everything with rot left + mask (see e.g. https://devblogs.microsoft.com/oldnewthing/20180810-00/?p=99465), A64 is rot right + mask (https://www.scs.stanford.edu/~zyedidia/arm64/ubfm.html), and the A64 logic immediates use basically the same mask generation logic. (So it can be shared if desired, in a small design.)
- I have seen datapath details for some Intel designs that used funnel shift right for all usual shifts.
In conversationabout 14 days ago from gnusocial.jppermalink
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1. Domain not in remote thumbnail source whitelist: devblogs.microsoft.com
  The PowerPC 600 series, part 5: Rotates and shifts - The Old New Thing
  from Raymond Chen
  Get out your Swiss army knife.
2. No result found on File_thumbnail lookup.
  UBFM -- A64

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