diff options
Diffstat (limited to 'fpu/softfloat-parts.c.inc')
-rw-r--r-- | fpu/softfloat-parts.c.inc | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index 9a67ab2bea..a203811299 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -413,3 +413,129 @@ static FloatPartsN *partsN(mul)(FloatPartsN *a, FloatPartsN *b, a->sign = sign; return a; } + +/* + * Returns the result of multiplying the floating-point values `a' and + * `b' then adding 'c', with no intermediate rounding step after the + * multiplication. The operation is performed according to the + * IEC/IEEE Standard for Binary Floating-Point Arithmetic 754-2008. + * The flags argument allows the caller to select negation of the + * addend, the intermediate product, or the final result. (The + * difference between this and having the caller do a separate + * negation is that negating externally will flip the sign bit on NaNs.) + * + * Requires A and C extracted into a double-sized structure to provide the + * extra space for the widening multiply. + */ +static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b, + FloatPartsN *c, int flags, float_status *s) +{ + int ab_mask, abc_mask; + FloatPartsW p_widen, c_widen; + + ab_mask = float_cmask(a->cls) | float_cmask(b->cls); + abc_mask = float_cmask(c->cls) | ab_mask; + + /* + * It is implementation-defined whether the cases of (0,inf,qnan) + * and (inf,0,qnan) raise InvalidOperation or not (and what QNaN + * they return if they do), so we have to hand this information + * off to the target-specific pick-a-NaN routine. + */ + if (unlikely(abc_mask & float_cmask_anynan)) { + return parts_pick_nan_muladd(a, b, c, s, ab_mask, abc_mask); + } + + if (flags & float_muladd_negate_c) { + c->sign ^= 1; + } + + /* Compute the sign of the product into A. */ + a->sign ^= b->sign; + if (flags & float_muladd_negate_product) { + a->sign ^= 1; + } + + if (unlikely(ab_mask != float_cmask_normal)) { + if (unlikely(ab_mask == float_cmask_infzero)) { + goto d_nan; + } + + if (ab_mask & float_cmask_inf) { + if (c->cls == float_class_inf && a->sign != c->sign) { + goto d_nan; + } + goto return_inf; + } + + g_assert(ab_mask & float_cmask_zero); + if (c->cls == float_class_normal) { + *a = *c; + goto return_normal; + } + if (c->cls == float_class_zero) { + if (a->sign != c->sign) { + goto return_sub_zero; + } + goto return_zero; + } + g_assert(c->cls == float_class_inf); + } + + if (unlikely(c->cls == float_class_inf)) { + a->sign = c->sign; + goto return_inf; + } + + /* Perform the multiplication step. */ + p_widen.sign = a->sign; + p_widen.exp = a->exp + b->exp + 1; + frac_mulw(&p_widen, a, b); + if (!(p_widen.frac_hi & DECOMPOSED_IMPLICIT_BIT)) { + frac_add(&p_widen, &p_widen, &p_widen); + p_widen.exp -= 1; + } + + /* Perform the addition step. */ + if (c->cls != float_class_zero) { + /* Zero-extend C to less significant bits. */ + frac_widen(&c_widen, c); + c_widen.exp = c->exp; + + if (a->sign == c->sign) { + parts_add_normal(&p_widen, &c_widen); + } else if (!parts_sub_normal(&p_widen, &c_widen)) { + goto return_sub_zero; + } + } + + /* Narrow with sticky bit, for proper rounding later. */ + frac_truncjam(a, &p_widen); + a->sign = p_widen.sign; + a->exp = p_widen.exp; + + return_normal: + if (flags & float_muladd_halve_result) { + a->exp -= 1; + } + finish_sign: + if (flags & float_muladd_negate_result) { + a->sign ^= 1; + } + return a; + + return_sub_zero: + a->sign = s->float_rounding_mode == float_round_down; + return_zero: + a->cls = float_class_zero; + goto finish_sign; + + return_inf: + a->cls = float_class_inf; + goto finish_sign; + + d_nan: + float_raise(float_flag_invalid, s); + parts_default_nan(a, s); + return a; +} |