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[FAST486]

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Fix several bugs in Fast486RotateOperation.


svn path=/branches/ntvdm/; revision=60969
This commit is contained in:
Aleksandar Andrejevic 2013-11-13 02:38:36 +00:00
parent 677810ea95
commit c7de214d81
1 changed files with 20 additions and 19 deletions
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39
lib/fast486/opgroups.c
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@ -161,17 +161,17 @@ Fast486RotateOperation(PFAST486_STATE State,
UCHAR Count)
{
ULONG HighestBit = 1 << (Bits - 1);
ULONG MaxValue = HighestBit | (HighestBit - 1);
ULONG Result;
/* Normalize the count */
Count &= 0x1F;
if (Operation <= 1) Count %= Bits;
else if (Operation <= 3) Count %= Bits + 1;
/* If the count is zero, do nothing */
if (Count == 0)
{
Result = Value;
goto SetFlags;
}
if (Count == 0) return Value;
/* Check which operation is this */
switch (Operation)
@ -205,14 +205,14 @@ Fast486RotateOperation(PFAST486_STATE State,
/* RCL */
case 2:
{
Result = (Value << Count)
| (State->Flags.Cf << (Count - 1))
| (Value >> (Bits - Count + 1));
Result = (Value << Count) | (State->Flags.Cf << (Count - 1));
/* Complete the calculation, but make sure we don't shift by too much */
if ((Bits - Count) < 31) Result |= Value >> (Bits - Count + 1);
/* Update CF and OF */
State->Flags.Cf = ((Value & (1 << (Bits - Count))) != 0);
if (Count == 1) State->Flags.Of = State->Flags.Cf
^ ((Result & HighestBit) != 0);
if (Count == 1) State->Flags.Of = State->Flags.Cf ^ ((Result & HighestBit) != 0);
break;
}
@ -220,14 +220,16 @@ Fast486RotateOperation(PFAST486_STATE State,
/* RCR */
case 3:
{
Result = (Value >> Count)
| (State->Flags.Cf << (Bits - Count))
| (Value << (Bits - Count + 1));
/* Update OF */
if (Count == 1) State->Flags.Of = State->Flags.Cf ^ ((Value & HighestBit) != 0);
/* Update CF and OF */
State->Flags.Cf = ((Value & (1 << (Bits - Count))) != 0);
if (Count == 1) State->Flags.Of = State->Flags.Cf
^ ((Result & (HighestBit >> 1)) != 0);
Result = (Value >> Count) | (State->Flags.Cf << (Bits - Count));
/* Complete the calculation, but make sure we don't shift by too much */
if ((Bits - Count) < 31) Result |= Value << (Bits - Count + 1);
/* Update CF */
State->Flags.Cf = ((Value & (1 << (Count - 1))) != 0);
break;
}
@ -274,11 +276,10 @@ Fast486RotateOperation(PFAST486_STATE State,
}
}
SetFlags:
if (Operation >= 4)
{
/* Update ZF, SF and PF */
State->Flags.Zf = (Result == 0);
State->Flags.Zf = ((Result & MaxValue) == 0);
State->Flags.Sf = ((Result & HighestBit) != 0);
State->Flags.Pf = Fast486CalculateParity(Result);
}