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[FAST486]

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Implement FSQRT using the Babylonian method.


svn path=/trunk/; revision=67874
This commit is contained in:
Aleksandar Andrejevic 2015-05-23 23:44:10 +00:00
parent fe6672870b
commit c1600b9458
1 changed files with 59 additions and 2 deletions
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61
reactos/lib/fast486/fpu.c
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@ -1390,6 +1390,63 @@ Fast486FpuArithmeticOperation(PFAST486_STATE State,
}
}
/*
* Calculates using:
* x[0] = s
* x[n + 1] = (x[n] + s / x[n]) / 2
*/
static inline BOOLEAN FASTCALL
Fast486FpuCalculateSquareRoot(PFAST486_STATE State,
PCFAST486_FPU_DATA_REG Operand,
PFAST486_FPU_DATA_REG Result)
{
FAST486_FPU_DATA_REG Value = *Operand;
FAST486_FPU_DATA_REG PrevValue = FpuZero;
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;
}
}
/* Loop until it converges */
while (Value.Sign != PrevValue.Sign
|| Value.Exponent != PrevValue.Exponent
|| Value.Mantissa != PrevValue.Mantissa)
{
FAST486_FPU_DATA_REG Temp;
/* Save the current value */
PrevValue = Value;
/* Divide the operand by the current value */
if (!Fast486FpuDivide(State, Operand, &Value, &Temp)) return FALSE;
/* Add the result of that division to the current value */
if (!Fast486FpuAdd(State, &Value, &Temp, &Value)) return FALSE;
/* Halve the current value */
if (!Fast486FpuMultiply(State, &Value, &FpuInverseNumber[1], &Value)) return FALSE;
}
*Result = Value;
return TRUE;
}
static inline BOOLEAN FASTCALL
Fast486FpuLoadEnvironment(PFAST486_STATE State,
INT Segment,
@ -2111,8 +2168,8 @@ FAST486_OPCODE_HANDLER(Fast486FpuOpcodeD9)
/* FSQRT */
case 0x3A:
{
// TODO: NOT IMPLEMENTED
UNIMPLEMENTED;
Fast486FpuCalculateSquareRoot(State, &FPU_ST(0), &FPU_ST(0));
FPU_UPDATE_TAG(0);
break;
}