Re: [Qemu-devel] [PATCH 4/4] target-m68k: add fscale, fgetman and fgetexp

[Richard Henderson]

On 07/03/2017 12:50 PM, Laurent Vivier wrote:
>                 fmove.x #0x000000000ABCDEF12345,%fp0
>                 fgetman.x %fp0,%fp6
> fp0            2.1518178707571747286191852003521627e-4938       (raw
> 0x0000000000000abcdef12345)
> fp6            1.342222103012886691431049257516861      (raw
> 0x3fff0000abcdef1234500000)

This one shows exactly what I was thinking about.

> So I guess the mantissa must be shifted to left until we have a 1 in the
> explicit integer part bit?

Yes.

Please try fgetexp on this same input.
I suspect the answer is -16384 - clz64(val->l.lower).
Otherwise the behaviour of fgetman above doesn't make sense.


r~