From 8a59fecfa5196e643ccea45ddd2b355b90c626cb Mon Sep 17 00:00:00 2001
From: Sir Richard <sir_richard@svn.reactos.org>
Date: Fri, 5 Nov 2010 15:58:34 +0000
Subject: [PATCH] [NTOS]: Implement the idle loop in C.

svn path=/trunk/; revision=49485
---
 reactos/ntoskrnl/ke/i386/ctxswitch.S | 123 ---------------------------
 reactos/ntoskrnl/ke/i386/thrdini.c   |  62 +++++++++++++-
 2 files changed, 60 insertions(+), 125 deletions(-)

diff --git a/reactos/ntoskrnl/ke/i386/ctxswitch.S b/reactos/ntoskrnl/ke/i386/ctxswitch.S
index 716db3b3b11..518d05da460 100644
--- a/reactos/ntoskrnl/ke/i386/ctxswitch.S
+++ b/reactos/ntoskrnl/ke/i386/ctxswitch.S
@@ -498,129 +498,6 @@ QuantumEnd:
     ret
 .endfunc
 
-.globl @KiIdleLoop@0
-.func @KiIdleLoop@0, @KiIdleLoop@0
-@KiIdleLoop@0:
-
-    /* Set EBX */
-    mov ebx, fs:[KPCR_SELF]
-
-    /* Jump into mainline code */
-    jmp MainLoop
-
-CpuIdle:
-    /* Call the CPU's idle function */
-    lea ecx, [ebx+KPCR_PRCB_POWER_STATE_IDLE_FUNCTION]
-    call [ecx]
-
-MainLoop:
-    /* Cycle interrupts for 1 cycle */
-    sti
-    nop
-    nop
-    cli
-
-    /* Check if we have to deliver DPCs, timers, or deferred threads */
-    mov eax, [ebx+KPCR_PRCB_DPC_QUEUE_DEPTH]
-    or eax, [ebx+KPCR_PRCB_TIMER_REQUEST]
-#ifdef CONFIG_SMP
-    or eax, [ebx+KPCR_PRCB_DEFERRED_READY_LIST_HEAD]
-#endif
-    jz CheckSchedule
-
-    mov cl, DISPATCH_LEVEL
-    call @HalClearSoftwareInterrupt@4
-    
-    /* Handle the above */
-    lea ecx, [ebx+KPCR_PRCB_DATA]
-    call @KiRetireDpcList@4
-
-CheckSchedule:
-    /* Check if a next thread is queued */
-    cmp dword ptr [ebx+KPCR_PRCB_NEXT_THREAD], 0
-#ifdef CONFIG_SMP
-    jz NoNextThread
-#else
-    jz CpuIdle
-#endif
-
-#ifdef CONFIG_SMP
-    /* There is, raise IRQL to synch level */
-    call _KeRaiseIrqlToSynchLevel@0
-#endif
-    sti
-
-    /* Set the current thread to ready */
-    mov edi, [ebx+KPCR_CURRENT_THREAD]
-#ifdef CONFIG_SMP
-    mov byte ptr [edi+KTHREAD_SWAP_BUSY], 1
-
-    /* Acquire the PRCB Lock */
-    lock bts dword ptr [ebx+KPCR_PRCB_PRCB_LOCK], 0
-    jnb CheckNext
-    lea ecx, [ebx+KPCR_PRCB_PRCB_LOCK]
-    call @KefAcquireSpinLockAtDpcLevel@4
-#endif
-
-CheckNext:
-    /* Check if the next thread is the current */
-    mov esi, [ebx+KPCR_PRCB_NEXT_THREAD]
-#ifdef CONFIG_SMP
-    cmp esi, edi
-    jz SameThread
-#endif
-
-    /* Clear the next thread and set this one instead */
-    and dword ptr [ebx+KPCR_PRCB_NEXT_THREAD], 0
-    mov [ebx+KPCR_CURRENT_THREAD], esi
-
-    /* Set the thread as running */
-    mov byte ptr [esi+KTHREAD_STATE_], Running
-
-#ifdef CONFIG_SMP
-    /* Disable the idle scheduler and release the PRCB lock */
-    and byte ptr [ebx+KPCR_PRCB_IDLE_SCHEDULE], 0
-    and dword ptr [ebx+KPCR_PRCB_PRCB_LOCK], 0
-#endif
-
-SwapContext:
-    /* Swap context at APC_LEVEL */
-    mov ecx, APC_LEVEL
-    call @KiSwapContextInternal@0
-
-#ifdef CONFIG_SMP
-    /* Lower to DPC level */
-    mov ecx, DISPATCH_LEVEL
-    call @KfLowerIrql@4
-#endif
-    jmp MainLoop
-
-#ifdef CONFIG_SMP
-SameThread:
-    /* Clear the next thread, and put the thread as ready after lock release */
-    and dword ptr [ebx+KPCR_PRCB_NEXT_THREAD], 0
-    and dword ptr [ebx+KPCR_PRCB_PRCB_LOCK], 0
-    and byte ptr [edi+KTHREAD_STATE_], Ready
-    jmp MainLoop
-
-NoNextThread:
-    /* Check if the idle scheduler is enabled */
-    cmp byte ptr [ebx+KPCR_PRCB_IDLE_SCHEDULE], 0
-    jz CpuIdle
-
-    /* It is, so call the scheduler */
-    lea ecx, [ebx+KPCR_PRCB_DATA]
-    call @KiIdleSchedule@4
-    test eax, eax
-
-    /* Get new thread pointers and either swap or idle loop again */
-    mov esi, eax
-    mov edi, [ebx+KPCR_PRCB_IDLE_THREAD]
-    jnz SwapContext
-    jmp MainLoop
-#endif
-.endfunc
-
 /* FIXFIX: Move to C code ****/
 .globl _Ki386SetupAndExitToV86Mode@4
 .func Ki386SetupAndExitToV86Mode@4
diff --git a/reactos/ntoskrnl/ke/i386/thrdini.c b/reactos/ntoskrnl/ke/i386/thrdini.c
index 219e2883922..2fdcc6505fe 100644
--- a/reactos/ntoskrnl/ke/i386/thrdini.c
+++ b/reactos/ntoskrnl/ke/i386/thrdini.c
@@ -249,6 +249,64 @@ KiInitializeContextThread(IN PKTHREAD Thread,
     Thread->KernelStack = (PVOID)CtxSwitchFrame;
 }
 
+VOID
+FASTCALL
+KiIdleLoop(VOID)
+{
+    PKPRCB Prcb = KeGetCurrentPrcb();
+    PKTHREAD OldThread, NewThread;
+
+    /* Initialize the idle loop: disable interrupts */
+    _enable();
+    __asm__("nop; nop");
+    _disable();
+    
+    /* Now loop forever */
+    while (TRUE)
+    {
+        /* Check for pending timers, pending DPCs, or pending ready threads */
+        if ((Prcb->DpcData[0].DpcQueueDepth) ||
+            (Prcb->TimerRequest) ||
+            (Prcb->DeferredReadyListHead.Next))
+        {
+            /* Quiesce the DPC software interrupt */
+            HalClearSoftwareInterrupt(DISPATCH_LEVEL);
+        
+            /* Handle it */
+            KiRetireDpcList(Prcb);
+        }
+    
+        /* Check if a new thread is scheduled for execution */
+        if (Prcb->NextThread)
+        {
+            /* Enable interupts */
+            _enable();
+        
+            /* Capture current thread data */
+            OldThread = Prcb->CurrentThread;
+            NewThread = Prcb->NextThread;
+        
+            /* Set new thread data */
+            Prcb->NextThread = NULL;
+            Prcb->CurrentThread = NewThread;
+        
+            /* The thread is now running */
+            NewThread->State = Running;
+        
+            /* Switch away from the idle thread */
+            KiSwapContext(OldThread, NewThread);
+            
+            /* We are back in the idle thread -- disable interrupts again */
+            _enable();
+            __asm__("nop");
+            _disable();
+        }
+        else
+        {
+            /* Continue staying idle. Note the HAL returns with interrupts on */
+            Prcb->PowerState.IdleFunction(&Prcb->PowerState);
+        }
+    }
+}
+
 /* EOF */
-
-