Re: [Qemu-devel] [PATCH 0/7] target-m68k: implement 680x0 FPU

[Richard Henderson]

On 01/18/2017 01:05 PM, Laurent Vivier wrote:
> This series modifies the original ColdFire FPU implementation
> to use floatx80 instead of float64 internally as this
> is the native datatype for 680x0. I didn't keep the float64
> type for ColdFire, but if someone thinks it's required I
> can update this series in this way.

I think at minimum you'll need to round to float64.  But this control is also 
needed for 68040 FPU, so probably you can use the same helpers.

I'm thinking something like

void helper_foo_d(args);
{
  ...
  r80 = floatx80_foo(args);
  r64 = floatx80_to_float64(r80, &env->fp_status);
  r80 = float64_to_floatx80(r64, &env->fp_status);
  [store r80]
  ...
}

since iirc 68040 has fadd.d, fadd.s to go with fadd.


r~