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[FAST486]

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Implement FYL2X and FYL2XP1.


svn path=/trunk/; revision=67821
This commit is contained in:
Aleksandar Andrejevic 2015-05-18 15:27:08 +00:00
parent de0880752b
commit b96fb17aab
1 changed files with 160 additions and 4 deletions
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164
reactos/lib/fast486/fpu.c
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@ -1019,6 +1019,110 @@ Fast486FpuCalculateTwoPowerMinusOne(PFAST486_STATE State,
*Result = TempResult;
}
/*
* Calculates using the identities:
* log2(x) = log10(x) / log10(2)
* log10(x)= sum { -1^(n+1) * x^n / n!, n >= 1 }
*/
static inline BOOLEAN FASTCALL
Fast486FpuCalculateLogBase2(PFAST486_STATE State,
PFAST486_FPU_DATA_REG Operand,
PFAST486_FPU_DATA_REG Result)
{
INT i;
FAST486_FPU_DATA_REG Value = *Operand;
FAST486_FPU_DATA_REG SeriesElement;
FAST486_FPU_DATA_REG TempResult;
FAST486_FPU_DATA_REG TempValue;
LONGLONG UnbiasedExp = (LONGLONG)Operand->Exponent - FPU_REAL10_BIAS;
if (Operand->Sign)
{
/* Raise the invalid operation exception */
State->FpuStatus.Ie = TRUE;
if (State->FpuControl.Im)
{
/* Return the indefinite NaN */
Result->Sign = TRUE;
Result->Exponent = FPU_MAX_EXPONENT + 1;
Result->Mantissa = FPU_INDEFINITE_MANTISSA;
return TRUE;
}
else
{
Fast486FpuException(State);
return FALSE;
}
}
/* Get only the mantissa as a floating-pointer number between 1 and 2 */
Value.Exponent = FPU_REAL10_BIAS;
/* Check if it's denormalized */
if (!FPU_IS_NORMALIZED(&Value))
{
ULONG Bits;
State->FpuStatus.De = TRUE;
if (!State->FpuControl.Dm)
{
Fast486FpuException(State);
return FALSE;
}
/* Normalize the number */
Bits = CountLeadingZeros64(Value.Mantissa);
UnbiasedExp -= Bits;
Value.Mantissa <<= Bits;
}
/* Subtract one from the value */
if (!Fast486FpuSubtract(State, &Value, &FpuOne, &Value)) return FALSE;
/* Calculate the base 10 logarithm */
SeriesElement = TempResult = Value;
for (i = 2; i < INVERSE_NUMBERS_COUNT / 2; i++)
{
if (!Fast486FpuMultiply(State, &SeriesElement, &Value, &SeriesElement))
{
/* An exception occurred */
return FALSE;
}
/* Toggle the sign of the series element */
SeriesElement.Sign = !SeriesElement.Sign;
/* Divide it by the counter */
if (!Fast486FpuMultiply(State, &SeriesElement, &FpuInverseNumber[i - 1], &TempValue))
{
/* An exception occurred */
return FALSE;
}
/* And add it to the result */
if (!Fast486FpuAdd(State, &TempResult, &TempValue, &TempResult))
{
/* An exception occurred */
return FALSE;
}
}
/* Now convert the base 10 logarithm into a base 2 logarithm */
if (!Fast486FpuDivide(State, &TempResult, &FpuLgTwo, &TempResult)) return FALSE;
/*
* Add the exponent to the result
* log2(x * 2^y) = log2(x) + log2(2^y) = log2(x) + y
*/
Fast486FpuFromInteger(State, UnbiasedExp, &TempValue);
if (!Fast486FpuAdd(State, &TempValue, &TempResult, &TempResult)) return FALSE;
*Result = TempResult;
return TRUE;
}
/*
* Calculates using the identity:
* sin(x) = sum { -1^n * x^(2n + 1) / (2n + 1)!, n >= 0 }
@ -1726,8 +1830,31 @@ FAST486_OPCODE_HANDLER(Fast486FpuOpcodeD9)
/* FYL2X */
case 0x31:
{
// TODO: NOT IMPLEMENTED
UNIMPLEMENTED;
FAST486_FPU_DATA_REG Logarithm;
if (FPU_GET_TAG(0) == FPU_TAG_EMPTY || FPU_GET_TAG(1) == FPU_TAG_EMPTY)
{
State->FpuStatus.Ie = TRUE;
if (!State->FpuControl.Im) Fast486FpuException(State);
break;
}
if (!Fast486FpuCalculateLogBase2(State, &FPU_ST(0), &Logarithm))
{
/* Exception occurred */
break;
}
if (!Fast486FpuMultiply(State, &Logarithm, &FPU_ST(1), &FPU_ST(1)))
{
/* Exception occurred */
break;
}
/* Pop the stack so that the result ends up in ST0 */
Fast486FpuPop(State);
FPU_UPDATE_TAG(0);
break;
}
@ -1828,8 +1955,37 @@ FAST486_OPCODE_HANDLER(Fast486FpuOpcodeD9)
/* FYL2XP1 */
case 0x39:
{
// TODO: NOT IMPLEMENTED
UNIMPLEMENTED;
FAST486_FPU_DATA_REG Value, Logarithm;
if (FPU_GET_TAG(0) == FPU_TAG_EMPTY || FPU_GET_TAG(1) == FPU_TAG_EMPTY)
{
State->FpuStatus.Ie = TRUE;
if (!State->FpuControl.Im) Fast486FpuException(State);
break;
}
if (!Fast486FpuAdd(State, &FPU_ST(0), &FpuOne, &Value))
{
/* Exception occurred */
break;
}
if (!Fast486FpuCalculateLogBase2(State, &Value, &Logarithm))
{
/* Exception occurred */
break;
}
if (!Fast486FpuMultiply(State, &Logarithm, &FPU_ST(1), &FPU_ST(1)))
{
/* Exception occurred */
break;
}
/* Pop the stack so that the result ends up in ST0 */
Fast486FpuPop(State);
FPU_UPDATE_TAG(0);
break;
}