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Reverse Engineering the Constants in the Pentium FPU

151 pointsby mef4 months ago

4 comments

lifthrasiir4 months ago
I guess the unused entries spell &quot;bad FC&quot; (for floating constant). Also I think constants 6 through 10 are relevant for the decimal-to-binary conversion or vice versa, as evident from the following observation:<p><pre><code> 0x5c3bd5191b525a249 ~= 2^123 &#x2F; 10^17 0x470de4df820000000 = 2^13 * 10^16</code></pre>
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garaetjjte4 months ago
Fun trivia: for many years Intel documentation was wrong on error bounds in trigonometric functions: <a href="https:&#x2F;&#x2F;randomascii.wordpress.com&#x2F;2014&#x2F;10&#x2F;09&#x2F;intel-underestimates-error-bounds-by-1-3-quintillion&#x2F;" rel="nofollow">https:&#x2F;&#x2F;randomascii.wordpress.com&#x2F;2014&#x2F;10&#x2F;09&#x2F;intel-underesti...</a>
kens4 months ago
Author here for your Pentium questions...
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cmpxchg8b4 months ago
Ken, how has the technology for interconnects changed over the years? Seeing all of these disparate regions in 2D it really interests me on how they are routed.