added more code for process scheduling

stix/kernel/Context.st

@@ -0,0 +1,186 @@
+#class(#pointer) Context(Apex)
+{
+}
+
+#class(#pointer) MethodContext(Context)
+{
+	#dcl sender ip sp ntmprs method receiver home origin.
+
+	#method pc
+	{
+		^ip
+	}
+
+	#method pc: anInteger
+	{
+		ip := anInteger.
+		"sp := sp - 1."  "whould this always work??? "
+	}
+
+	#method sp
+	{
+		^sp.
+
+	}
+	#method sp: anInteger
+	{
+		sp := anInteger.
+	}
+
+	#method pc: aPC sp: aSP
+	{
+		ip := aPC.
+		sp := aSP.
+		##sp := sp - 1.
+	}
+}
+
+#class(#pointer) BlockContext(Context)
+{
+	#dcl caller ip sp ntmprs nargs source  home origin.
+
+	#method fork
+	{
+		"crate a new process in the runnable state"
+## TODO
+	}
+
+	#method newProcess
+	{
+		"create a new process in the suspended state"
+## TODO
+	}
+
+	#method newProcessWith: anArray
+	{
+		"create a new process in the suspended state passing the elements
+		 of anArray as block arguments"
+## TODO
+	}
+
+	#method value
+	{
+		<primitive: #_block_value>
+	}
+
+	#method value: a 
+	{
+		<primitive: #_block_value>
+	}
+
+	#method value: a value: b
+	{
+		<primitive: #_block_value>
+	}
+
+	#method value: a value: b value: c
+	{
+		<primitive: #_block_value>
+	}
+
+	#method ifTrue: aBlock
+	{
+		^(self value) ifTrue: aBlock.
+	}
+
+	#method ifFalse: aBlock
+	{
+		^(self value) ifFalse: aBlock.
+	}
+
+	#method ifTrue: trueBlock ifFalse: falseBlock
+	{
+		^(self value) ifTrue: trueBlock ifFalse: falseBlock
+	}
+
+	#method whileTrue: aBlock
+	{
+## http://stackoverflow.com/questions/2500483/is-there-a-way-in-a-message-only-language-to-define-a-whiletrue-message-without
+
+## ----------------------------------------------------------------------------
+
+##		^(self value) ifTrue: [aBlock value. self whileTrue: aBlock].
+
+## ----------------------------------------------------------------------------
+
+		## less block context before whileTrue: is recursively sent.
+		## whileTrue: is sent in a method context.
+##		(self value) ifFalse: [^nil].
+##		aBlock value. 
+##		self whileTrue: aBlock.
+
+## ----------------------------------------------------------------------------
+
+## ----------------------------------------------------------------------------
+		| pc sp xsp |
+
+		sp := thisContext sp.
+		sp := sp - 1. "decrement sp by 1 becuase thisContext pushed above affects the sp method"
+		pc := thisContext pc.
+		self value ifFalse: [ ^nil "^self" ].
+		aBlock value.
+		##thisContext pc: pc - 3 sp: sp.
+		##thisContext pc: pc + 2 sp: sp.   
+		thisContext pc: pc + 1 sp: sp.   
+		## this +2 or - 3 above is dependent on the byte code instruction size used for 'store'  
+		## +2 to skip STORE_INTO_TEMP(pc) and POP_STACKTOP.
+		## TODO: make it independent of the byte code size 
+
+## ----------------------------------------------------------------------------
+
+##        #<label>:
+##		thisContext pc: #<label> sp: sp.
+##
+##		| pc |
+##		pc := thisContext pc.
+##		^self value ifTrue: [aBlock value. thisContext pc: pc]
+
+## ----------------------------------------------------------------------------
+
+##		self value ifTrue: [ aBlock value. thisContext restart. ].
+	}
+
+	#method pc
+	{
+		^ip
+	}
+
+	#method pc: anInteger
+	{
+		ip := anInteger.
+	}
+	
+	#method sp
+	{
+		^sp
+	}
+
+	#method sp: anInteger
+	{
+		sp := anInteger.
+	}
+
+	#method restart
+	{
+		ip := source pc.
+	}
+
+
+
+	"------ TODO: -------------------------------------"
+	#method on: anError do: anExceptionBlock
+	{
+		"TODO: handle if anError is an ErrorSet .."
+	}
+
+	#method ensure: aBlock
+	{
+	}
+
+	#method ifCurtailed: aBlock
+	{
+	}
+
+	"------ TODO: -------------------------------------"
+}
+