rubyx/lib/arm/logic_instruction.rb

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module Arm
class LogicInstruction < Register::LogicInstruction
include Arm::Constants
def initialize(result , left , right , attributes = {})
super(result ,left , right , attributes)
@attributes[:update_status] = 0 if @attributes[:update_status] == nil
@attributes[:condition_code] = :al if @attributes[:condition_code] == nil
@operand = 0
raise "Left arg must be given #{inspect}" unless @left
@immediate = 0
end
def assemble(io, assembler)
# don't overwrite instance variables, to make assembly repeatable
left = @left
operand = @operand
immediate = @immediate
right = @right
if @left.is_a?(Virtual::ObjectConstant)
# do pc relative addressing with the difference to the instuction
# 8 is for the funny pipeline adjustment (ie pointing to fetch and not execute)
right = @left.position - self.position - 8
left = :pc
end
# automatic wrapping, for machine internal code and testing
if( right.is_a? Fixnum )
right = Virtual::IntegerConstant.new( right )
end
if (right.is_a?(Virtual::IntegerConstant))
if true #TODO (right.integer.fits_u8?)
# no shifting needed
operand = right.integer
immediate = 1
elsif (op_with_rot = calculate_u8_with_rr(right))
operand = op_with_rot
immediate = 1
# raise "hmm"
else
raise "cannot fit numeric literal argument in operand #{right.inspect}"
end
elsif (right.is_a?(Symbol) or right.is_a?(::Register::RegisterReference))
operand = reg_code(right) #integer means the register the integer is in (otherwise constant)
immediate = 0 # ie not immediate is register
else
raise "invalid operand argument #{right.inspect} , #{inspect}"
end
op = shift_handling
instuction_class = 0b00 # OPC_DATA_PROCESSING
val = shift(operand , 0)
val |= shift(op , 0) # any barral action, is already shifted
val |= shift(reg_code(@result) , 12)
val |= shift(reg_code(left) , 12+4)
val |= shift(@attributes[:update_status] , 12+4+4)#20
val |= shift(op_bit_code , 12+4+4 +1)
val |= shift(immediate , 12+4+4 +1+4)
val |= shift(instuction_class , 12+4+4 +1+4+1)
val |= shift(cond_bit_code , 12+4+4 +1+4+1+2)
io.write_uint32 val
end
def shift val , by
raise "Not integer #{val}:#{val.class} #{inspect}" unless val.is_a? Fixnum
val << by
end
end
end