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[FAST486]

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Fix several division related problems:
- In UnsignedDivMod128, fix the leading zero calculation for 128-bit numbers.
- In Fast486FpuDivide, there's no need to increase the exponent by 64 (adding zeros
at the end of a number after the decimal point changes nothing).
- FDIV/FDIVR were reversed


svn path=/trunk/; revision=67820
This commit is contained in:
Aleksandar Andrejevic 2015-05-18 12:17:40 +00:00
parent ec471e2759
commit de0880752b
1 changed files with 6 additions and 7 deletions
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13
reactos/lib/fast486/fpu.c
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@ -203,9 +203,9 @@ UnsignedDivMod128(ULONGLONG DividendLow,
* Calculate the number of significant bits the current
* divisor has more than the original divisor
*/
Bits = CountLeadingZeros64(Divisor) + 64;
Bits -= (CurrentHigh > 0ULL) ? CountLeadingZeros64(CurrentHigh) : 64;
Bits -= (CurrentLow > 0ULL) ? CountLeadingZeros64(CurrentLow) : 64;
Bits = CountLeadingZeros64(Divisor);
if (CurrentHigh > 0ULL) Bits -= CountLeadingZeros64(CurrentHigh);
else Bits -= CountLeadingZeros64(CurrentLow);
if (Bits)
{
@ -923,11 +923,10 @@ Fast486FpuDivide(PFAST486_STATE State,
}
/* Calculate the exponent of the result */
Exponent = (LONG)FirstOperand->Exponent - (LONG)SecondOperand->Exponent - 64;
Exponent = (LONG)FirstOperand->Exponent - (LONG)SecondOperand->Exponent - 1;
/* Divide the two mantissas */
Remainder = UnsignedDivMod128(0ULL,
/* Notice the 64 above - this is the high part */
FirstOperand->Mantissa,
SecondOperand->Mantissa,
&QuotientLow,
@ -1169,14 +1168,14 @@ Fast486FpuArithmeticOperation(PFAST486_STATE State,
/* FDIV */
case 6:
{
Fast486FpuDivide(State, DestOperand, SourceOperand, DestOperand);
Fast486FpuDivide(State, SourceOperand, DestOperand, DestOperand);
break;
}
/* FDIVR */
case 7:
{
Fast486FpuDivide(State, SourceOperand, DestOperand, DestOperand);
Fast486FpuDivide(State, DestOperand, SourceOperand, DestOperand);
break;
}
}