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[FAST486]

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Implement Fast486FpuMultiply properly.


svn path=/trunk/; revision=66216
This commit is contained in:
Aleksandar Andrejevic 2015-02-10 17:29:26 +00:00
parent fdc2ad5b23
commit 7ffd32d418
1 changed files with 72 additions and 2 deletions
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74
reactos/lib/fast486/fpu.c
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@ -696,6 +696,37 @@ Fast486FpuMultiply(PFAST486_STATE State,
PFAST486_FPU_DATA_REG Result)
{
FAST486_FPU_DATA_REG TempResult;
LONG Exponent;
if (FPU_IS_INDEFINITE(FirstOperand)
|| FPU_IS_INDEFINITE(SecondOperand)
|| (FPU_IS_ZERO(FirstOperand) && FPU_IS_INFINITY(SecondOperand))
|| (FPU_IS_INFINITY(FirstOperand) && FPU_IS_ZERO(SecondOperand)))
{
/* The result will be indefinite */
Result->Sign = TRUE;
Result->Exponent = FPU_MAX_EXPONENT + 1;
Result->Mantissa = FPU_INDEFINITE_MANTISSA;
return;
}
if (FPU_IS_ZERO(FirstOperand) || FPU_IS_ZERO(SecondOperand))
{
/* The result will be zero */
Result->Sign = FirstOperand->Sign ^ SecondOperand->Sign;
Result->Exponent = 0;
Result->Mantissa = 0ULL;
return;
}
if (FPU_IS_INFINITY(FirstOperand) || FPU_IS_INFINITY(SecondOperand))
{
/* The result will be infinity */
Result->Sign = FirstOperand->Sign ^ SecondOperand->Sign;
Result->Exponent = FPU_MAX_EXPONENT + 1;
Result->Mantissa = FPU_MANTISSA_HIGH_BIT;
return;
}
if ((!FPU_IS_NORMALIZED(FirstOperand) || !FPU_IS_NORMALIZED(SecondOperand)))
{
@ -709,12 +740,51 @@ Fast486FpuMultiply(PFAST486_STATE State,
}
}
/* Calculate the sign */
TempResult.Sign = FirstOperand->Sign ^ SecondOperand->Sign;
/* Calculate the exponent */
Exponent = (LONG)FirstOperand->Exponent + (LONG)SecondOperand->Exponent - FPU_REAL10_BIAS;
/* Calculate the mantissa */
UnsignedMult128(FirstOperand->Mantissa,
SecondOperand->Mantissa,
&TempResult.Mantissa);
TempResult.Exponent = FirstOperand->Exponent + SecondOperand->Exponent;
TempResult.Sign = FirstOperand->Sign ^ SecondOperand->Sign;
if (Exponent < 0)
{
/* Raise the underflow exception */
State->FpuStatus.Ue = TRUE;
if (!State->FpuControl.Um)
{
Fast486FpuException(State);
return;
}
/* The exponent will be zero */
TempResult.Exponent = 0;
/* If possible, denormalize the result, otherwise make it zero */
if (Exponent > -64) TempResult.Mantissa >>= (-Exponent);
else TempResult.Mantissa = 0ULL;
}
else if (Exponent > FPU_MAX_EXPONENT)
{
/* Raise the overflow exception */
State->FpuStatus.Oe = TRUE;
if (!State->FpuControl.Om)
{
Fast486FpuException(State);
return;
}
/* Make the result infinity */
TempResult.Exponent = FPU_MAX_EXPONENT + 1;
TempResult.Mantissa = FPU_MANTISSA_HIGH_BIT;
}
else TempResult.Exponent = (USHORT)Exponent;
/* Normalize the result */
Fast486FpuNormalize(State, &TempResult);