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fpu: add mechanism to check for invalid long double formats

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All operations that take a floatx80 as an operand need to have their
inputs checked for malformed encodings. In all of these cases, use the
function floatx80_invalid_encoding to perform the check. If an invalid
operand is found, raise an invalid operation exception, and then return
either NaN (for fp-typed results) or the integer indefinite value (the
minimum representable signed integer value, for int-typed results).

For the non-quiet comparison operations, this touches adjacent code in
order to pass style checks.

Signed-off-by: Andrew Dutcher <andrew@andrewdutcher.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1471392895-17324-1-git-send-email-andrew@andrewdutcher.com
[PMM: changed "1 << 63" to "1ULL << 63" to fix compile errors]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Andrew Dutcher 2016-08-16 17:14:55 -07:00 • committed by Peter Maydell
parent 9e8204b1de
commit d1eb8f2acb
2 changed files with 115 additions and 16 deletions
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15
include/fpu/softfloat.h
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@ -658,6 +658,21 @@ static inline int floatx80_is_any_nan(floatx80 a)
return ((a.high & 0x7fff) == 0x7fff) && (a.low<<1);
}
/*----------------------------------------------------------------------------
| 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.
*----------------------------------------------------------------------------*/
static inline bool floatx80_invalid_encoding(floatx80 a)
{
return (a.low & (1ULL << 63)) == 0 && (a.high & 0x7FFF) != 0;
}
#define floatx80_zero make_floatx80(0x0000, 0x0000000000000000LL)
#define floatx80_one make_floatx80(0x3fff, 0x8000000000000000LL)
#define floatx80_ln2 make_floatx80(0x3ffe, 0xb17217f7d1cf79acLL)