context.c

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/*
 * PROJECT:         ReactOS Kernel
 * LICENSE:         BSD - See COPYING.ARM in the top level directory
 * FILE:            ntoskrnl/ke/i386/context.c
 * PURPOSE:         Context Switching Related Code
 * PROGRAMMERS:     ReactOS Portable Systems Group
 */
 
/* INCLUDES *******************************************************************/
 
#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>
 
/* GLOBALS ********************************************************************/
 
/* FUNCTIONS ******************************************************************/
 
VOID
NTAPI
KiSwapProcess(IN PKPROCESS NewProcess,
              IN PKPROCESS OldProcess)
{
    PKIPCR Pcr = (PKIPCR)KeGetPcr();
#ifdef CONFIG_SMP
    LONG SetMember;
 
    /* Update active processor mask */
    SetMember = (LONG)Pcr->SetMember;
    InterlockedXor((PLONG)&NewProcess->ActiveProcessors, SetMember);
    InterlockedXor((PLONG)&OldProcess->ActiveProcessors, SetMember);
#endif
 
    /* Check for new LDT */
    if (NewProcess->LdtDescriptor.LimitLow != OldProcess->LdtDescriptor.LimitLow)
    {
        if (NewProcess->LdtDescriptor.LimitLow)
        {
            KeSetGdtSelector(KGDT_LDT,
                             ((PULONG)&NewProcess->LdtDescriptor)[0],
                             ((PULONG)&NewProcess->LdtDescriptor)[1]);
            Ke386SetLocalDescriptorTable(KGDT_LDT);
        }
        else
        {
            Ke386SetLocalDescriptorTable(0);
        }
    }
 
    /* Update CR3 */
    __writecr3(NewProcess->DirectoryTableBase[0]);
 
    /* Clear GS */
    Ke386SetGs(0);
 
    /* Update IOPM offset */
    Pcr->TSS->IoMapBase = NewProcess->IopmOffset;
}