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InterpreterStackPagesLSB.class.st
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InterpreterStackPagesLSB.class.st
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"
I am a class that helps simulate the StackInterpreter's stack organization on little-endian platforms.
"
Class {
#name : #InterpreterStackPagesLSB,
#superclass : #InterpreterStackPages,
#category : #'VMMaker-InterpreterSimulation'
}
{ #category : #'memory access' }
InterpreterStackPagesLSB >> byteAt: byteAddress [
| lowBits long |
lowBits := byteAddress bitAnd: 3.
long := self longAt: byteAddress - lowBits.
^(lowBits caseOf: {
[0] -> [ long ].
[1] -> [ long bitShift: -8 ].
[2] -> [ long bitShift: -16 ].
[3] -> [ long bitShift: -24 ]
}) bitAnd: 16rFF
]
{ #category : #'memory access' }
InterpreterStackPagesLSB >> byteAt: byteAddress put: byte [
| lowBits long longAddress |
lowBits := byteAddress bitAnd: 3.
longAddress := byteAddress - lowBits.
long := self longAt: longAddress.
long := lowBits caseOf: {
[0] -> [ (long bitAnd: 16rFFFFFF00) bitOr: byte ].
[1] -> [ (long bitAnd: 16rFFFF00FF) bitOr: (byte bitShift: 8) ].
[2] -> [ (long bitAnd: 16rFF00FFFF) bitOr: (byte bitShift: 16) ].
[3] -> [ (long bitAnd: 16r00FFFFFF) bitOr: (byte bitShift: 24) ]
}.
self longAt: longAddress put: long.
^byte
]