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Date: Wed, 4 Jun 2008 15:38:22 -0500 From: Kumar Gala <galak@...nel.crashing.org> To: David Miller <davem@...emloft.net> Cc: lkml List <linux-kernel@...r.kernel.org>, libc-alpha@...rceware.org Subject: math-emu issue with fp divide David, You seem to be the last person to touch the math-emu code in the kernel so I figured you might have some insights. I'm trying to move the powerpc math-emu code to use the include/math-emu bits. In doing so I've been using TestFloat to see how good or bad we are doing. For the most part the current math-emu code that PPC uses has a number of issues that the code in include/math-emu seems to solve (plus bugs we've had for ever that no one every realized). Anyways, I've come across a case that we are flagging underflow and inexact because we think we have a denormalized result from a double precision divide: 000.FFFFFFFFFFFFF / 3FE.FFFFFFFFFFFFE soft: 001.0000000000000 ..... syst: 001.0000000000000 ...ux What it looks like is the results out of FP_DIV_D are: D: sign: 0 mantissa: 01000000 00000000 exp: -1023 (0) The problem seems like we aren't normalizing the result and bumping the exp. So I was wondering if you had any idea if FP_DIV_D should be doing that or if when we call FP_PACK_DP/_FP_PACK_CANONICAL if that could should be doing it. thanks - k -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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