diff options
| author | Lucas Mateus Castro (alqotel) | 2022-08-05 16:15:21 +0200 |
|---|---|---|
| committer | Daniel Henrique Barboza | 2022-08-31 19:08:05 +0200 |
| commit | c40da5c6fb6dd243e906900de1d22cf20e32a8cd (patch) | |
| tree | 8cb7144ea5d9f025bcc0fb5d574abf5a544046f9 | |
| parent | ppc/pnv: Add initial P9/10 SBE model (diff) | |
| download | qemu-c40da5c6fb6dd243e906900de1d22cf20e32a8cd.tar.gz qemu-c40da5c6fb6dd243e906900de1d22cf20e32a8cd.tar.xz qemu-c40da5c6fb6dd243e906900de1d22cf20e32a8cd.zip | |
fpu: Add rebias bool, value and operation
Added the possibility of recalculating a result if it overflows or
underflows, if the result overflow and the rebias bool is true then the
intermediate result should have 3/4 of the total range subtracted from
the exponent. The same for underflow but it should be added to the
exponent of the intermediate number instead.
Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220805141522.412864-2-lucas.araujo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
| -rw-r--r-- | fpu/softfloat-parts.c.inc | 21 | ||||
| -rw-r--r-- | fpu/softfloat.c | 2 | ||||
| -rw-r--r-- | include/fpu/softfloat-types.h | 4 |
3 files changed, 25 insertions, 2 deletions
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index bbeadaa189..a9f268fcab 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -214,18 +214,35 @@ static void partsN(uncanon_normal)(FloatPartsN *p, float_status *s, p->frac_lo &= ~round_mask; } } else if (unlikely(exp >= exp_max)) { - flags |= float_flag_overflow | float_flag_inexact; - if (overflow_norm) { + flags |= float_flag_overflow; + if (s->rebias_overflow) { + exp -= fmt->exp_re_bias; + } else if (overflow_norm) { + flags |= float_flag_inexact; exp = exp_max - 1; frac_allones(p); p->frac_lo &= ~round_mask; } else { + flags |= float_flag_inexact; p->cls = float_class_inf; exp = exp_max; frac_clear(p); } } frac_shr(p, frac_shift); + } else if (unlikely(s->rebias_underflow)) { + flags |= float_flag_underflow; + exp += fmt->exp_re_bias; + 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++; + } + p->frac_lo &= ~round_mask; + } + frac_shr(p, frac_shift); } else if (s->flush_to_zero) { flags |= float_flag_output_denormal; p->cls = float_class_zero; diff --git a/fpu/softfloat.c b/fpu/softfloat.c index 4a871ef2a1..c7454c3eb1 100644 --- a/fpu/softfloat.c +++ b/fpu/softfloat.c @@ -521,6 +521,7 @@ typedef struct { typedef struct { int exp_size; int exp_bias; + int exp_re_bias; int exp_max; int frac_size; int frac_shift; @@ -532,6 +533,7 @@ typedef struct { #define FLOAT_PARAMS_(E) \ .exp_size = E, \ .exp_bias = ((1 << E) - 1) >> 1, \ + .exp_re_bias = (1 << (E - 1)) + (1 << (E - 2)), \ .exp_max = (1 << E) - 1 #define FLOAT_PARAMS(E, F) \ diff --git a/include/fpu/softfloat-types.h b/include/fpu/softfloat-types.h index 7a6ea881d8..0884ec4ef7 100644 --- a/include/fpu/softfloat-types.h +++ b/include/fpu/softfloat-types.h @@ -195,6 +195,10 @@ typedef struct float_status { bool snan_bit_is_one; bool use_first_nan; bool no_signaling_nans; + /* should overflowed results subtract re_bias to its exponent? */ + bool rebias_overflow; + /* should underflowed results add re_bias to its exponent? */ + bool rebias_underflow; } float_status; #endif /* SOFTFLOAT_TYPES_H */ |