diff options
| -rw-r--r-- | include/fpu/softfloat-types.h | 14 | ||||
| -rw-r--r-- | include/fpu/softfloat.h | 68 | ||||
| -rw-r--r-- | target/m68k/cpu.c | 28 |
3 files changed, 77 insertions, 33 deletions
diff --git a/include/fpu/softfloat-types.h b/include/fpu/softfloat-types.h index e1732beba4..b1941384ae 100644 --- a/include/fpu/softfloat-types.h +++ b/include/fpu/softfloat-types.h @@ -333,8 +333,22 @@ typedef enum __attribute__((__packed__)) { /* * Are Pseudo-infinities (Inf with the Integer bit zero) valid? * If so, floatx80_is_infinity() will return true for them. + * If not, floatx80_invalid_encoding will return false for them, + * and using them as inputs to a float op will raise Invalid. */ floatx80_pseudo_inf_valid = 2, + /* + * Are Pseudo-NaNs (NaNs where the Integer bit is zero) valid? + * If not, floatx80_invalid_encoding() will return false for them, + * and using them as inputs to a float op will raise Invalid. + */ + floatx80_pseudo_nan_valid = 4, + /* + * Are Unnormals (0 < exp < 0x7fff, Integer bit zero) valid? + * If not, floatx80_invalid_encoding() will return false for them, + * and using them as inputs to a float op will raise Invalid. + */ + floatx80_unnormal_valid = 8, } FloatX80Behaviour; /* diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h index 1c8f3cbb78..c18ab2cb60 100644 --- a/include/fpu/softfloat.h +++ b/include/fpu/softfloat.h @@ -1073,41 +1073,45 @@ static inline bool floatx80_unordered_quiet(floatx80 a, floatx80 b, /*---------------------------------------------------------------------------- | Return whether the given value is an invalid floatx80 encoding. -| Invalid floatx80 encodings arise when the integer bit is not set, but -| the exponent is not zero. The only times the integer bit is permitted to -| be zero is in subnormal numbers and the value zero. -| This includes what the Intel software developer's manual calls pseudo-NaNs, -| pseudo-infinities and un-normal numbers. It does not include -| pseudo-denormals, which must still be correctly handled as inputs even -| if they are never generated as outputs. +| Invalid floatx80 encodings may arise when the integer bit is not set +| correctly; this is target-specific. In Intel terminology the +| categories are: +| exp == 0, int = 0, mantissa == 0 : zeroes +| exp == 0, int = 0, mantissa != 0 : denormals +| exp == 0, int = 1 : pseudo-denormals +| 0 < exp < 0x7fff, int = 0 : unnormals +| 0 < exp < 0x7fff, int = 1 : normals +| exp == 0x7fff, int = 0, mantissa == 0 : pseudo-infinities +| exp == 0x7fff, int = 1, mantissa == 0 : infinities +| exp == 0x7fff, int = 0, mantissa != 0 : pseudo-NaNs +| exp == 0x7fff, int = 1, mantissa == 0 : NaNs +| +| The usual IEEE cases of zero, denormal, normal, inf and NaN are always valid. +| x87 permits as input also pseudo-denormals. +| m68k permits all those and also pseudo-infinities, pseudo-NaNs and unnormals. +| +| Since we don't have a target that handles floatx80 but prohibits +| pseudo-denormals in input, we don't currently have a floatx80_behaviour +| flag for that case, but instead always accept it. Conveniently this +| means that all cases with either exponent 0 or the integer bit set are +| valid for all targets. *----------------------------------------------------------------------------*/ static inline bool floatx80_invalid_encoding(floatx80 a, float_status *s) { -#if defined(TARGET_M68K) - /*------------------------------------------------------------------------- - | With m68k, the explicit integer bit can be zero in the case of: - | - zeros (exp == 0, mantissa == 0) - | - denormalized numbers (exp == 0, mantissa != 0) - | - unnormalized numbers (exp != 0, exp < 0x7FFF) - | - infinities (exp == 0x7FFF, mantissa == 0) - | - not-a-numbers (exp == 0x7FFF, mantissa != 0) - | - | For infinities and NaNs, the explicit integer bit can be either one or - | zero. - | - | The IEEE 754 standard does not define a zero integer bit. Such a number - | is an unnormalized number. Hardware does not directly support - | denormalized and unnormalized numbers, but implicitly supports them by - | trapping them as unimplemented data types, allowing efficient conversion - | in software. - | - | See "M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL", - | "1.6 FLOATING-POINT DATA TYPES" - *------------------------------------------------------------------------*/ - return false; -#else - return (a.low & (1ULL << 63)) == 0 && (a.high & 0x7FFF) != 0; -#endif + if ((a.low >> 63) || (a.high & 0x7fff) == 0) { + /* Anything with the Integer bit set or the exponent 0 is valid */ + return false; + } + + if ((a.high & 0x7fff) == 0x7fff) { + if (a.low) { + return !(s->floatx80_behaviour & floatx80_pseudo_nan_valid); + } else { + return !(s->floatx80_behaviour & floatx80_pseudo_inf_valid); + } + } else { + return !(s->floatx80_behaviour & floatx80_unnormal_valid); + } } #define floatx80_zero make_floatx80(0x0000, 0x0000000000000000LL) diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c index 56b23de21f..505fa97a53 100644 --- a/target/m68k/cpu.c +++ b/target/m68k/cpu.c @@ -111,9 +111,35 @@ static void m68k_cpu_reset_hold(Object *obj, ResetType type) * m68k-specific floatx80 behaviour: * * default Infinity values have a zero Integer bit * * input Infinities may have the Integer bit either 0 or 1 + * * pseudo-denormals supported for input and output + * * don't raise Invalid for pseudo-NaN/pseudo-Inf/Unnormal + * + * With m68k, the explicit integer bit can be zero in the case of: + * - zeros (exp == 0, mantissa == 0) + * - denormalized numbers (exp == 0, mantissa != 0) + * - unnormalized numbers (exp != 0, exp < 0x7FFF) + * - infinities (exp == 0x7FFF, mantissa == 0) + * - not-a-numbers (exp == 0x7FFF, mantissa != 0) + * + * For infinities and NaNs, the explicit integer bit can be either one or + * zero. + * + * The IEEE 754 standard does not define a zero integer bit. Such a number + * is an unnormalized number. Hardware does not directly support + * denormalized and unnormalized numbers, but implicitly supports them by + * trapping them as unimplemented data types, allowing efficient conversion + * in software. + * + * See "M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL", + * "1.6 FLOATING-POINT DATA TYPES" + * + * Note though that QEMU's fp emulation does directly handle both + * denormal and unnormal values, and does not trap to guest software. */ set_floatx80_behaviour(floatx80_default_inf_int_bit_is_zero | - floatx80_pseudo_inf_valid, + floatx80_pseudo_inf_valid | + floatx80_pseudo_nan_valid | + floatx80_unnormal_valid, &env->fp_status); nan = floatx80_default_nan(&env->fp_status); |