And no sooner have I said that, and I think of a way to use _BitScanForward64() that improves upon the original by 70+%:

C:\test\C>gcm
anonyM: gcm for  s=2147483648 & r=1 to 1073741824 took:8.535316994670
anonyM: gcm2 for s=2147483648 & r=1 to 1073741824 took:2.271266720696

[download]

Pre-masking the scanned var, avoids the later subtraction being conditional:

U64 gcm2( U64 max, U64 lcm ) {
    I32 b;

    _BitScanForward64( &b, lcm & 0xfff );
    lcm <<= ( 12 - b );
    return ( max / lcm ) * lcm;
}

[download]
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". I'm with torvalds on this
In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked

In reply to Re^3: Simple arithmetic? (And the winner is ... ) by BrowserUk
in thread Simple arithmetic? by BrowserUk

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