Re: Division using FMAC, reciprocal estimates and Newton-Raphson - eg ia64, rs6000, SSE, ARM MaverickCrunch?

["Hasjim Williams" <linux-cirrus at lists dot futaris dot org>]

On Sat, 10 May 2008 11:59:16 +0100, "Martin Guy" <martinwguy@yahoo.it>
said:
> On 5/9/08, Paolo Bonzini <bonzini@gnu.org> wrote:
> >  The idea is to use integer arithmetic to compute the right exponent, and
> > the lookup table to estimate the mantissa.

> The current soft-fp routine in libm seems to use a variant of this,
> but of course it may be faster if implemented using the Maverick's
> 64-bit add/sub/cmp.

ARM doesn't use the soft-fp routines in libm for division (in
glibc/soft-fp).  For gcc, there is a gcc/config/ieee754-sf.S and
ieee754-df.S that implements divsf3 and divdf3.

For SQRT, it should use these functions, on soft-float and any
coprocessor that doesn't have a sqrt function, i.e. MaverickCrunch.

http://www.gnu.org/software/libc/manual/html_node/Misc-FP-Arithmetic.html#Misc-FP-Arithmetic

mentions the fma / fmaf functions which do a fused multiply-add, at a
higher precision.  MaverickCrunch has a fma function for 32-bit
integers, which could be extended for 64-bit ints, floats and doubles...