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From: Rich Felker <dalias@aerifal.cx>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: correctly rounded sqrt
Date: Thu, 15 Mar 2012 01:07:48 -0400
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On Thu, Mar 15, 2012 at 04:23:04AM +0100, Szabolcs Nagy wrote:
> but now that we figured out the fpu status register based
> solution this does not matter..

Here's the asm version based on fpu status word. I'm not sure if it's
safe for non-default rounding modes but otherwise it should be
correct.

Rich


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.global sqrt
.type sqrt,@function
sqrt:	fldl 4(%esp)
	fsqrt
	fstsw %ax
	sub $12,%esp
	fld %st(0)
	fstpt (%esp)
	mov (%esp),%ecx
	and $0x7ff,%ecx
	cmp $0x400,%ecx
	jnz 1f
	and $0x200,%eax
	sub $0x100,%eax
	sub %eax,(%esp)
	fstp %st(0)
	fldt (%esp)
1:	add $12,%esp
	fstpl 4(%esp)
	fldl 4(%esp)
	ret

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