rubyx/lib/arm/instructions/memory_instruction.rb
2016-12-14 21:05:24 +02:00

97 lines
3.9 KiB
Ruby

module Arm
# ADDRESSING MODE 2
# Implemented: immediate offset with offset=0
class MemoryInstruction < Register::Instruction
include Constants
include Attributed
def initialize result , left , right = nil , attributes = {}
super(nil)
@attributes = attributes
@result = result
@left = left
@right = right
@attributes[:update_status] = 1 if @attributes[:update_status] == nil
@attributes[:condition_code] = :al if @attributes[:condition_code] == nil
@operand = 0
raise "alert" if right.is_a? Register::Label
@pre_post_index = @attributes[:pre_post_index] ? 0 : 1 #P flag
@add_offset = @attributes[:add_offset] ? 0 : 1 #U flag
@is_load = opcode.to_s[0] == "l" ? 1 : 0 #L (load) flag
end
def assemble(io)
# don't overwrite instance variables, to make assembly repeatable
rn = @rn
operand = @operand
add_offset = @add_offset
arg = @left
arg = arg.symbol if( arg.is_a? ::Register::RegisterValue )
#str / ldr are _serious instructions. With BIG possibilities not half are implemented
is_reg = arg.is_a?(::Register::RegisterValue)
if( arg.is_a?(Symbol) and not is_reg)
is_reg = (arg.to_s[0] == "r")
end
if (is_reg ) #symbol is register
rn = arg
if @right
operand = @right
#TODO better test, this operand integer (register) does not work. but sleep first
operand = operand.symbol if operand.is_a? ::Register::RegisterValue
unless( operand.is_a? Symbol) #TODO test/check/understand
add_offset = (operand < 0) ? 0 : 1
operand *= -1 if (operand < 0)
raise "offset too large (max 4095) #{arg} #{inspect}" if (@operand.abs > 4095)
end
end
elsif (arg.is_a?(Parfait::Object) or arg.is_a? Symbol ) #use pc relative
rn = :pc
operand = arg.position - self.position - 8 #stringtable is after code
add_offset = 1
if (operand.abs > 4095)
raise "reference offset too large/small (4095<#{operand}) #{arg} #{inspect}"
end
else
raise "invalid operand argument #{arg.inspect} #{inspect}"
end
#not sure about these 2 constants. They produce the correct output for str r0 , r1
# but i can't help thinking that that is because they are not used in that instruction and
# so it doesn't matter. Will see
add_offset = 1
# TODO to be continued
add_offset = 0 if @attributes[:add_offset]
w = 0 #W flag
byte_access = opcode.to_s[-1] == "b" ? 1 : 0 #B (byte) flag
instuction_class = 0b01 # OPC_MEMORY_ACCESS
if (operand.is_a?(Symbol) or operand.is_a?(::Register::RegisterValue))
val = reg_code(operand)
@pre_post_index = 0
i = 1 # not quite sure about this, but it gives the output of as. read read read.
else
i = 0 #I flag (third bit)
val = operand
end
# testing against gnu as, setting the flag produces correct output
# but gnu as produces same output for auto_inc or not, so that seems broken
# luckily auto_inc is not used and even if it clobbers unused reg in soml, but still
@pre_post_index = 1
op = shift_handling
val = shift(val , 0 ) # for the test
val |= shift(op , 0)
val |= shift(reg_code(@result) , 12 )
val |= shift(reg_code(rn) , 12 + 4) #16
val |= shift(@is_load , 12 + 4 + 4)
val |= shift(w , 12 + 4 + 4 + 1)
val |= shift(byte_access , 12 + 4 + 4 + 1 + 1)
val |= shift(add_offset , 12 + 4 + 4 + 1 + 1 + 1)
val |= shift(@pre_post_index, 12 + 4 + 4 + 1 + 1 + 1 + 1)#24
val |= shift(i , 12 + 4 + 4 + 1 + 1 + 1 + 1 + 1)
val |= shift(instuction_class,12 + 4 + 4 + 1 + 1 + 1 + 1 + 1 + 1)
val |= shift(cond_bit_code , 12 + 4 + 4 + 1 + 1 + 1 + 1 + 1 + 1 + 2)
io.write_uint32 val
end
end
end