Are you sure this is the correct order of execution? The instruction is
documented as first lowering the stack pointer, then writing to the new
location.
If a stack exception occurs, you might have esp off by 4.
Am 21.11.2014 10:46, schrieb aandreje...@svn.reactos.org:
Author: aandrejevic
Date: Fri Nov 21 09:46:57 2014
New Revision: 65441
URL: http://svn.reactos.org/svn/reactos?rev=65441&view=rev
Log:
[FAST486]
Attempt to write the value to the stack before subtracting from the actual ESP
register
in Fast486StackPush.
Modified:
trunk/reactos/lib/fast486/common.inl
Modified: trunk/reactos/lib/fast486/common.inl
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/fast486/common.inl?rev=65441&r1=65440&r2=65441&view=diff
==============================================================================
--- trunk/reactos/lib/fast486/common.inl [iso-8859-1] (original)
+++ trunk/reactos/lib/fast486/common.inl [iso-8859-1] Fri Nov 21
09:46:57 2014
@@ -317,15 +317,19 @@
return FALSE;
}
+ /* Store the value in SS:[ESP - 4] */
+ if (!Fast486WriteMemory(State,
+ FAST486_REG_SS,
+ State->GeneralRegs[FAST486_REG_ESP].Long -
sizeof(ULONG),
+ &Value,
+ sizeof(ULONG)))
+ {
+ /* Exception occurred */
+ return FALSE;
+ }
+
/* Subtract ESP by 4 */
State->GeneralRegs[FAST486_REG_ESP].Long -= sizeof(ULONG);
-
- /* Store the value in SS:ESP */
- return Fast486WriteMemory(State,
- FAST486_REG_SS,
- State->GeneralRegs[FAST486_REG_ESP].Long,
- &Value,
- sizeof(ULONG));
}
else
{
@@ -339,16 +343,22 @@
return FALSE;
}
+ /* Store the value in SS:[SP - 2] */
+ if (!Fast486WriteMemory(State,
+ FAST486_REG_SS,
+
LOWORD(State->GeneralRegs[FAST486_REG_ESP].LowWord - sizeof(USHORT)),
+ &ShortValue,
+ sizeof(USHORT)))
+ {
+ /* Exception occurred */
+ return FALSE;
+ }
+
/* Subtract SP by 2 */
State->GeneralRegs[FAST486_REG_ESP].LowWord -= sizeof(USHORT);
-
- /* Store the value in SS:SP */
- return Fast486WriteMemory(State,
- FAST486_REG_SS,
- State->GeneralRegs[FAST486_REG_ESP].LowWord,
- &ShortValue,
- sizeof(USHORT));
- }
+ }
+
+ return TRUE;
}
FORCEINLINE
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