95 lines
3.3 KiB
Ruby
95 lines
3.3 KiB
Ruby
module Arm
|
|
class CompareInstruction < Vm::CompareInstruction
|
|
include Arm::Constants
|
|
|
|
def initialize(left , right , attributes)
|
|
super(left , right, attributes)
|
|
@attributes[:condition_code] = :al if @attributes[:condition_code] == nil
|
|
@operand = 0
|
|
@immediate = 0
|
|
@attributes[:update_status] = 1
|
|
@rn = left
|
|
@rd = :r0
|
|
end
|
|
# arm instructions are pretty sensible, and always 4 bytes (thumb not supported)
|
|
def length
|
|
4
|
|
end
|
|
|
|
def assemble(io)
|
|
# don't overwrite instance variables, to make assembly repeatable
|
|
rn = @rn
|
|
operand = @operand
|
|
immediate = @immediate
|
|
|
|
arg = @right
|
|
if arg.is_a?(Vm::ObjectConstant)
|
|
# do pc relative addressing with the difference to the instuction
|
|
# 8 is for the funny pipeline adjustment (ie oc pointing to fetch and not execute)
|
|
arg = Vm::IntegerConstant.new( arg.position - self.position - 8 )
|
|
rn = :pc
|
|
end
|
|
if( arg.is_a? Fixnum ) #HACK to not have to change the code just now
|
|
arg = Vm::IntegerConstant.new( arg )
|
|
end
|
|
if (arg.is_a?(Vm::IntegerConstant))
|
|
if (arg.integer.fits_u8?)
|
|
# no shifting needed
|
|
operand = arg.integer
|
|
immediate = 1
|
|
elsif (op_with_rot = calculate_u8_with_rr(arg))
|
|
operand = op_with_rot
|
|
immediate = 1
|
|
raise "hmm"
|
|
else
|
|
raise "cannot fit numeric literal argument in operand #{arg.inspect}"
|
|
end
|
|
elsif (arg.is_a?(Symbol) or arg.is_a?(Vm::Integer))
|
|
operand = arg
|
|
immediate = 0
|
|
elsif (arg.is_a?(Arm::Shift))
|
|
rm_ref = arg.argument
|
|
immediate = 0
|
|
shift_op = {'lsl' => 0b000, 'lsr' => 0b010, 'asr' => 0b100,
|
|
'ror' => 0b110, 'rrx' => 0b110}[arg.type]
|
|
if (arg.type == 'ror' and arg.value.nil?)
|
|
# ror #0 == rrx
|
|
raise "cannot rotate by zero #{arg} #{inspect}"
|
|
end
|
|
|
|
arg1 = arg.value
|
|
if (arg1.is_a?(Vm::IntegerConstant))
|
|
if (arg1.value >= 32)
|
|
raise "cannot shift by more than 31 #{arg1} #{inspect}"
|
|
end
|
|
shift_imm = arg1.value
|
|
elsif (arg1.is_a?(Arm::Register))
|
|
shift_op val |= 0x1;
|
|
shift_imm = arg1.number << 1
|
|
elsif (arg.type == 'rrx')
|
|
shift_imm = 0
|
|
end
|
|
operand = rm_ref | (shift_op << 4) | (shift_imm << 4+3)
|
|
else
|
|
raise "invalid operand argument #{arg.inspect} , #{inspect}"
|
|
end
|
|
instuction_class = 0b00 # OPC_DATA_PROCESSING
|
|
val = (operand.is_a?(Symbol) or operand.is_a?(Vm::Integer)) ? reg_code(operand) : operand
|
|
val = 0 if val == nil
|
|
val = shift(val , 0)
|
|
raise inspect unless reg_code(@rd)
|
|
val |= shift(reg_code(@rd) , 12)
|
|
val |= shift(reg_code(rn) , 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 |