Hi Alex, On 12/11/2017 09:56 AM, Alex Bennée wrote: > This defines the same set of common constants for float 16 as defined > for 32 and 64 bit floats. These are often used by target helper > functions. > > Signed-off-by: Alex Bennée <alex.ben...@linaro.org> > --- > include/fpu/softfloat.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h > index 17dfe60dbd..5a9258c57c 100644 > --- a/include/fpu/softfloat.h > +++ b/include/fpu/softfloat.h > @@ -395,6 +395,13 @@ static inline float16 float16_set_sign(float16 a, int > sign) > return make_float16((float16_val(a) & 0x7fff) | (sign << 15)); > } > > +#define float16_zero make_float16(0)
ok
> +#define float16_one make_float16(0x3a00)
I'm a bit confused...
>>> [np.fromstring(struct.pack("<H", x), dtype=np.float16)[0] for x in
[0, 0x3a00, 0x34d1, 0x4448, 0x3800, 0x7a00]]
[0.0, 0.75, 0.30103, 4.2812, 0.5, 49152.0]
However:
>>> ['0x' + binascii.hexlify(np.array([x], '>f2').tostring()) for x in
[0, 1, math.log(2), np.pi, 0.5, np.inf]]
['0x0000', '0x3c00', '0x398c', '0x4248', '0x3800', '0x7c00']
It seems the MSB bit of the mantissa got shifted as the LSB of the
biased exponent...
> +#define float16_ln2 make_float16(0x34d1)
incorrect? 0x398c
> +#define float16_pi make_float16(0x4448)
incorrect? 0x4248
> +#define float16_half make_float16(0x3800)
ok
> +#define float16_infinity make_float16(0x7a00)
incorrect? 0x7c00
> +
>
> /*----------------------------------------------------------------------------
> | The pattern for a default generated half-precision NaN.
>
> *----------------------------------------------------------------------------*/
>
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