Re: [Qemu-devel] How does ARM VFP is emulated?

[Peter Maydell]

On 17 August 2012 12:27, 陳韋任 (Wei-Ren Chen) <address@hidden> wrote:
> On Fri, Aug 17, 2012 at 10:29:24AM +0200, Laurent Desnogues wrote:
>> On Thursday, August 16, 2012, Oi Khote <address@hidden> wrote:
>> > So how exactly does VFP is being emulated.
>>
>> QEMU uses a library for FP computations, based on the softfloat package.
>
>   I thought QEMU emulates VFP itself

Depends how you think about it. We do emulate all the VFP
with integer operations...

>   But I am wrong, it acutally does this, right?
>
> float64 VFP_HELPER(sqrt, d)(float64 a, CPUARMState *env)
> {
>     return float64_sqrt(a, &env->vfp.fp_status);
> }
>
> And float64_sqrt is implemented in fpu/* .

...it just happens that the code that does generic IEEE floating
point emulation lives in fpu/ and is shared between all targets.
(That code is a library called 'softfloat' but we have modified
our copy of it quite a bit over the years.)

-- PMM