diff options
Diffstat (limited to 'fpu/softfloat-parts.c.inc')
| -rw-r--r-- | fpu/softfloat-parts.c.inc | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index 25bf99b..efdc724 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -133,3 +133,151 @@ static void partsN(canonicalize)(FloatPartsN *p, float_status *status, ? float_class_snan : float_class_qnan); } } + +/* + * Round and uncanonicalize a floating-point number by parts. There + * are FRAC_SHIFT bits that may require rounding at the bottom of the + * fraction; these bits will be removed. The exponent will be biased + * by EXP_BIAS and must be bounded by [EXP_MAX-1, 0]. + */ +static void partsN(uncanon)(FloatPartsN *p, float_status *s, + const FloatFmt *fmt) +{ + const int exp_max = fmt->exp_max; + const int frac_shift = fmt->frac_shift; + const uint64_t frac_lsb = fmt->frac_lsb; + const uint64_t frac_lsbm1 = fmt->frac_lsbm1; + const uint64_t round_mask = fmt->round_mask; + const uint64_t roundeven_mask = fmt->roundeven_mask; + uint64_t inc; + bool overflow_norm; + int exp, flags = 0; + + if (unlikely(p->cls != float_class_normal)) { + switch (p->cls) { + case float_class_zero: + p->exp = 0; + frac_clear(p); + return; + case float_class_inf: + g_assert(!fmt->arm_althp); + p->exp = fmt->exp_max; + frac_clear(p); + return; + case float_class_qnan: + case float_class_snan: + g_assert(!fmt->arm_althp); + p->exp = fmt->exp_max; + frac_shr(p, fmt->frac_shift); + return; + default: + break; + } + g_assert_not_reached(); + } + + switch (s->float_rounding_mode) { + case float_round_nearest_even: + overflow_norm = false; + inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1 ? frac_lsbm1 : 0); + break; + case float_round_ties_away: + overflow_norm = false; + inc = frac_lsbm1; + break; + case float_round_to_zero: + overflow_norm = true; + inc = 0; + break; + case float_round_up: + inc = p->sign ? 0 : round_mask; + overflow_norm = p->sign; + break; + case float_round_down: + inc = p->sign ? round_mask : 0; + overflow_norm = !p->sign; + break; + case float_round_to_odd: + overflow_norm = true; + inc = p->frac_lo & frac_lsb ? 0 : round_mask; + break; + default: + g_assert_not_reached(); + } + + exp = p->exp + fmt->exp_bias; + if (likely(exp > 0)) { + if (p->frac_lo & round_mask) { + flags |= float_flag_inexact; + if (frac_addi(p, p, inc)) { + frac_shr(p, 1); + p->frac_hi |= DECOMPOSED_IMPLICIT_BIT; + exp++; + } + } + frac_shr(p, frac_shift); + + if (fmt->arm_althp) { + /* ARM Alt HP eschews Inf and NaN for a wider exponent. */ + if (unlikely(exp > exp_max)) { + /* Overflow. Return the maximum normal. */ + flags = float_flag_invalid; + exp = exp_max; + frac_allones(p); + } + } else if (unlikely(exp >= exp_max)) { + flags |= float_flag_overflow | float_flag_inexact; + if (overflow_norm) { + exp = exp_max - 1; + frac_allones(p); + } else { + p->cls = float_class_inf; + exp = exp_max; + frac_clear(p); + } + } + } else if (s->flush_to_zero) { + flags |= float_flag_output_denormal; + p->cls = float_class_zero; + exp = 0; + frac_clear(p); + } else { + bool is_tiny = s->tininess_before_rounding || exp < 0; + + if (!is_tiny) { + FloatPartsN discard; + is_tiny = !frac_addi(&discard, p, inc); + } + + frac_shrjam(p, 1 - exp); + + if (p->frac_lo & round_mask) { + /* Need to recompute round-to-even/round-to-odd. */ + switch (s->float_rounding_mode) { + case float_round_nearest_even: + inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1 + ? frac_lsbm1 : 0); + break; + case float_round_to_odd: + inc = p->frac_lo & frac_lsb ? 0 : round_mask; + break; + default: + break; + } + flags |= float_flag_inexact; + frac_addi(p, p, inc); + } + + exp = (p->frac_hi & DECOMPOSED_IMPLICIT_BIT) != 0; + frac_shr(p, frac_shift); + + if (is_tiny && (flags & float_flag_inexact)) { + flags |= float_flag_underflow; + } + if (exp == 0 && frac_eqz(p)) { + p->cls = float_class_zero; + } + } + p->exp = exp; + float_raise(flags, s); +} |