On 9 January 2018 at 12:22, Alex Bennée <alex.ben...@linaro.org> wrote:
> We can now add float16_mul and use the common decompose and
> canonicalize functions to have a single implementation for
> float16/32/64 versions.
>
> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> ---
> fpu/softfloat.c | 207
> ++++++++++++++++++------------------------------
> include/fpu/softfloat.h | 1 +
> 2 files changed, 80 insertions(+), 128 deletions(-)
>
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index f89e47e3ef..6e9d4c172c 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -730,6 +730,85 @@ float64 float64_sub(float64 a, float64 b, float_status
> *status)
> return float64_round_pack_canonical(pr, status);
> }
>
> +/*
> + * Returns the result of multiplying the floating-point values `a' and
> + * `b'. The operation is performed according to the IEC/IEEE Standard
> + * for Binary Floating-Point Arithmetic.
> + */
> +
> +static decomposed_parts mul_decomposed(decomposed_parts a, decomposed_parts
> b,
> + float_status *s)
> +{
> + bool sign = a.sign ^ b.sign;
> +
> + if (a.cls == float_class_normal && b.cls == float_class_normal) {
> + uint64_t hi, lo;
> + int exp = a.exp + b.exp;
> +
> + mul64To128(a.frac, b.frac, &hi, &lo);
> + shift128RightJamming(hi, lo, DECOMPOSED_BINARY_POINT, &hi, &lo);
> + if (lo & DECOMPOSED_OVERFLOW_BIT) {
> + shift64RightJamming(lo, 1, &lo);
> + exp += 1;
> + }
> +
> + /* Re-use a */
> + a.exp = exp;
> + a.sign = sign;
> + a.frac = lo;
> + return a;
> + }
> + /* handle all the NaN cases */
> + if (a.cls >= float_class_qnan || b.cls >= float_class_qnan) {
> + return pick_nan_parts(a, b, s);
> + }
> + /* Inf * Zero == NaN */
> + if (((1 << a.cls) | (1 << b.cls)) ==
> + ((1 << float_class_inf) | (1 << float_class_zero))) {
This is kinda confusing...
> + s->float_exception_flags |= float_flag_invalid;
> + a.cls = float_class_dnan;
> + a.sign = sign;
> + return a;
> + }
> + /* Multiply by 0 or Inf */
> + if (a.cls == float_class_inf || a.cls == float_class_zero) {
> + a.sign = sign;
> + return a;
> + }
> + if (b.cls == float_class_inf || b.cls == float_class_zero) {
> + b.sign = sign;
> + return b;
> + }
> + g_assert_not_reached();
> +}
thanks
-- PMM
