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Re^5: powerpc double-double arithmetic

by bulk88 (Priest)
on Oct 10, 2013 at 12:00 UTC ( #1057730=note: print w/replies, xml ) Need Help??


in reply to Re^4: powerpc double-double arithmetic
in thread powerpc double-double arithmetic

So if its vector math op (SSE, etc), its really 2 64 bit doubles and not a "long double". Long double would mean over 64 bits of double/precision. You have "packed data" not a "long double". Does your CPU have 128 bit FP math (see also) or not? Does your compiler emulate 128 bit FP math (GCC yes as __float128)?

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Re^6: powerpc double-double arithmetic
by syphilis (Chancellor) on Oct 10, 2013 at 12:26 UTC
    The basics of its arithmetic is here.
    There's no 128 bit FP math with its gcc-4.6.3 compiler. I think the double-double technique precludes it. (Every other gcc-4.6.3 that I've seen has a quadmath.h that provides the __float128 type, but not this one - which is provided by Debian specifically for the PowerPC architecture.)

    Cheers,
    Rob

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