diff -r 76bcca2667a8 -r be7402f74d94 ProcessorScheduler.st
--- a/ProcessorScheduler.st	Fri Oct 18 15:20:50 1996 +0200
+++ b/ProcessorScheduler.st	Fri Oct 18 21:56:19 1996 +0200
@@ -26,7 +26,7 @@
 	category:'Kernel-Processes'
 !
 
-!ProcessorScheduler  class methodsFor:'documentation'!
+!ProcessorScheduler class methodsFor:'documentation'!
 
 copyright
 "
@@ -130,7 +130,7 @@
 "
 ! !
 
-!ProcessorScheduler  class methodsFor:'initialization'!
+!ProcessorScheduler class methodsFor:'initialization'!
 
 initialize
     "class setup: create the one-and-only instance of myself and
@@ -166,7 +166,7 @@
     "Modified: 23.9.1996 / 14:24:50 / stefan"
 ! !
 
-!ProcessorScheduler  class methodsFor:'instance creation'!
+!ProcessorScheduler class methodsFor:'instance creation'!
 
 new
     "there is (currently) only one processor ..."
@@ -174,7 +174,7 @@
     self error:'only one processor is allowed in the system'
 ! !
 
-!ProcessorScheduler  class methodsFor:'Signal constants'!
+!ProcessorScheduler class methodsFor:'Signal constants'!
 
 invalidProcessSignal
     ^ InvalidProcessSignal
@@ -182,7 +182,7 @@
     "Created: 23.9.1996 / 13:44:57 / stefan"
 ! !
 
-!ProcessorScheduler  class methodsFor:'instance release'!
+!ProcessorScheduler class methodsFor:'instance release'!
 
 informDispose
     "some Process has been garbage collected 
@@ -210,7 +210,7 @@
     ]
 ! !
 
-!ProcessorScheduler  class methodsFor:'primitive process primitives'!
+!ProcessorScheduler class methodsFor:'primitive process primitives'!
 
 threadCreate:aProcess withId:id
     "physical creation of a process.
@@ -288,7 +288,7 @@
 %}
 ! !
 
-!ProcessorScheduler  class methodsFor:'queries'!
+!ProcessorScheduler class methodsFor:'queries'!
 
 isPureEventDriven
     "this is temporary - (maybe not :-).
@@ -846,7 +846,7 @@
 
 threadSwitch:aProcess
     "continue execution in aProcess.
-     (warning: low level entry, no administration is done here)"
+     WARNING: this is a low level entry, no process administration is done here"
 
     |id pri ok oldProcess oldPri p singleStep wasBlocked|
 
@@ -873,9 +873,9 @@
     extern OBJ ___threadSwitch();
 
     if (__isSmallInteger(id)) {
-	ok = ___threadSwitch(__context, __intVal(id), (singleStep == true) ? 1 : 0);
+        ok = ___threadSwitch(__context, __intVal(id), (singleStep == true) ? 1 : 0);
     } else {
-	ok = false;
+        ok = false;
     }
 %}.
     "time passes spent in some other process ...
@@ -886,24 +886,91 @@
     currentPriority := oldProcess priority.
 
     ok ifFalse:[
-	"
-	 switch failed for some reason -
-	 destroy the bad process
-	"
-	p id ~~ 0 ifTrue:[
-	    'PROCESSOR: problem with process ' errorPrint. 
-		p id errorPrint. 
-		p name notNil ifTrue:[
-		    ' (' errorPrint. p name errorPrint. ')' errorPrint.
-		].
-		'; hard-terminate it.' errorPrintNL.
-	    p state:#suspended.
-	    self terminateNoSignal:p.
-	]
+        "
+         switch failed for some reason -
+         destroy the bad process
+        "
+        p id ~~ 0 ifTrue:[
+            'PROCESSOR: problem with process ' errorPrint. 
+                p id errorPrint. 
+                p name notNil ifTrue:[
+                    ' (' errorPrint. p name errorPrint. ')' errorPrint.
+                ].
+                '; hard-terminate it.' errorPrintNL.
+            p state:#suspended.
+            self terminateNoSignal:p.
+        ]
     ].
     zombie notNil ifTrue:[
-	self class threadDestroy:zombie.
-	zombie := nil
+        self class threadDestroy:zombie.
+        zombie := nil
+    ].
+    wasBlocked ifFalse:[OperatingSystem unblockInterrupts].
+!
+
+threadSwitch:aProcess from:aContext
+    "continue execution in aProcess, simulating a context switch
+     done by aContext 
+     (this is only cosmetic, hiding intermediate contexts from the visible
+      context chain).
+     WARNING: this is a low level entry, no process administration is done here"
+
+    |id pri ok oldProcess oldPri p singleStep wasBlocked sender|
+
+    (aProcess isNil or:[aProcess == activeProcess]) ifTrue:[^ self].
+
+    wasBlocked := OperatingSystem blockInterrupts.
+
+    oldProcess := activeProcess.
+    oldPri := currentPriority.
+
+    id := aProcess id.
+    pri := aProcess priority.
+    singleStep := aProcess isSingleStepping.
+    aProcess state:#active.
+    oldProcess setStateTo:#run if:#active.
+
+    "
+     no interrupts now - activeProcess has already been changed
+     (dont add any message sends here)
+    "
+    activeProcess := aProcess.
+    currentPriority := pri.
+%{
+    extern OBJ ___threadSwitch();
+
+    if (__isSmallInteger(id)) {
+        ok = ___threadSwitch(aContext, __intVal(id), (singleStep == true) ? 1 : 0);
+    } else {
+        ok = false;
+    }
+%}.
+    "time passes spent in some other process ...
+     ... here again"
+
+    p := activeProcess.
+    activeProcess := oldProcess.
+    currentPriority := oldProcess priority.
+
+    ok ifFalse:[
+        "
+         switch failed for some reason -
+         destroy the bad process
+        "
+        p id ~~ 0 ifTrue:[
+            'PROCESSOR: problem with process ' errorPrint. 
+                p id errorPrint. 
+                p name notNil ifTrue:[
+                    ' (' errorPrint. p name errorPrint. ')' errorPrint.
+                ].
+                '; hard-terminate it.' errorPrintNL.
+            p state:#suspended.
+            self terminateNoSignal:p.
+        ]
+    ].
+    zombie notNil ifTrue:[
+        self class threadDestroy:zombie.
+        zombie := nil
     ].
     wasBlocked ifFalse:[OperatingSystem unblockInterrupts].
 ! !
@@ -1285,9 +1352,14 @@
 !
 
 interruptActive
-    "interrupt the current process"
-
-    activeProcess interrupt
+    "interrupt the current process 
+     - this message is sent by the VM, when a process is about to be switched to,
+     and that process has the interrupted flag bit set.
+     Pass the interrupt to the process, which may do whatever it likes with it."
+
+    activeProcess interruptedIn:thisContext sender
+
+    "Modified: 18.10.1996 / 20:44:59 / cg"
 !
 
 processTermination
@@ -2053,13 +2125,17 @@
 
 ioInterrupt
     "data arrived while waiting - switch to scheduler process which will decide 
-     what to do now."
+     what to do now.
+     This method is called by the VM' interrupt handling mechanism.
+     Notice, that at the time of the message, we are still in the context
+     of whichever process is currently running."
 
     gotIOInterrupt := true.
     interruptedProcess := activeProcess.
-    self threadSwitch:scheduler
+    self threadSwitch:scheduler from:thisContext sender
 
     "Modified: 21.12.1995 / 16:17:40 / stefan"
+    "Modified: 18.10.1996 / 20:36:05 / cg"
 !
 
 removeCorruptedFds
@@ -2156,10 +2232,15 @@
 
 timerInterrupt
     "timer expired while waiting - switch to scheduler process which will decide 
-     what to do now."
+     what to do now.
+     This method is called by the VM' interrupt handling mechanism.
+     Notice, that at the time of the message, we are still in the context
+     of whichever process is currently running."
 
     interruptedProcess := activeProcess.
-    self threadSwitch:scheduler
+    self threadSwitch:scheduler from:thisContext sender
+
+    "Modified: 18.10.1996 / 20:35:54 / cg"
 !
 
 waitForEventOrTimeout
@@ -2251,9 +2332,9 @@
     "Modified: 18.7.1996 / 20:42:17 / cg"
 ! !
 
-!ProcessorScheduler  class methodsFor:'documentation'!
+!ProcessorScheduler class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libbasic/ProcessorScheduler.st,v 1.95 1996-10-18 12:34:09 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic/ProcessorScheduler.st,v 1.96 1996-10-18 19:56:19 cg Exp $'
 ! !
 ProcessorScheduler initialize!