Class: Vm::Instructions::MemoryAccessOperations::VirtualSegmentOperation

Inherits:
Object
  • Object
show all
Defined in:
lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb

Constant Summary collapse

VIRTUAL_SEGMENT_TO_POINTER_NAME = 
{
  'argument' => 'ARG',
  'local' => 'LCL',
  'this' => 'THIS',
  'that' => 'THAT',
}.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(operation, segment, index) ⇒ VirtualSegmentOperation

Returns a new instance of VirtualSegmentOperation.



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# File 'lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb', line 15

def initialize(operation, segment, index)
  @operation = operation
  @segment = segment
  @index = index
end

Instance Attribute Details

#index ⇒ Object (readonly)

Returns the value of attribute index.



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# File 'lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb', line 13

def index
  @index
end

#operation ⇒ Object (readonly)

Returns the value of attribute operation.



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# File 'lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb', line 13

def operation
  @operation
end

#segment ⇒ Object (readonly)

Returns the value of attribute segment.



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# File 'lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb', line 13

def segment
  @segment
end

Class Method Details

.segments ⇒ Object 



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# File 'lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb', line 59

def self.segments
  VIRTUAL_SEGMENT_TO_POINTER_NAME.keys
end

Instance Method Details

#to_asm ⇒ Object 



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# File 'lib/hackasm/vm/instructions/memory_access_operations/virtual_segment_operation.rb', line 21

def to_asm
  if operation == "push"
    %Q{
      @#{index}
      D=A
      @#{VIRTUAL_SEGMENT_TO_POINTER_NAME[segment]}
      A=M+D
      D=M
      @SP
      A=M
      M=D
      @SP
      M=M+1
    }.strip
  else
    %Q{
      @SP
      M=M-1
      @SP
      A=M
      D=M
      @R14
      M=D
      @#{index}
      D=A
      @#{VIRTUAL_SEGMENT_TO_POINTER_NAME[segment]}
      D=M+D
      @R15
      M=D
      @R14
      D=M
      @R15
      A=M
      M=D
    }.strip
  end
end