91 lines
3.2 KiB
Ruby
91 lines
3.2 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
|
|
@add_offset = @attributes[:add_offset] ? 0 : 1 #U flag
|
|
@is_load = opcode.to_s[0] == "l" ? 1 : 0 #L (load) flag
|
|
end
|
|
|
|
#str / ldr are _serious instructions. With BIG possibilities not half are implemented
|
|
# don't overwrite instance variables, to make assembly repeatable
|
|
#TODO better test, this operand integer (register) does not work.
|
|
def assemble(io)
|
|
arg = @left
|
|
arg = arg.symbol if( arg.is_a? ::Register::RegisterValue )
|
|
is_reg = arg.is_a?(::Register::RegisterValue)
|
|
is_reg = (arg.to_s[0] == "r") if( arg.is_a?(Symbol) and not is_reg)
|
|
|
|
raise "invalid operand argument #{arg.inspect} #{inspect}" unless (is_reg )
|
|
operand = get_operand
|
|
|
|
#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
|
|
if (operand.is_a?(Symbol) or operand.is_a?(::Register::RegisterValue))
|
|
val = reg_code(operand)
|
|
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
|
|
|
|
val = shift(val , 0 )
|
|
val |= shift(reg_code(arg) , 16)
|
|
val |= shift(i , 25)
|
|
write_val(val, io)
|
|
end
|
|
|
|
def write_val(val, io)
|
|
val |= shift(shift_handling , 0)
|
|
val |= shift(reg_code(@result) , 12 )
|
|
val |= shift(@is_load , 20)
|
|
val |= shift(byte_access , 22)
|
|
val |= shift(add_offset , 23)
|
|
val |= shift(0, 21)
|
|
val |= shift(1, 24) #pre_post index , not used
|
|
val |= instruction_code
|
|
val |= condition_code
|
|
io.write_uint32 val
|
|
end
|
|
def get_operand
|
|
return @operand unless @right
|
|
operand = @right
|
|
operand = operand.symbol if operand.is_a? ::Register::RegisterValue
|
|
unless( operand.is_a? Symbol)
|
|
# TODO test/check/understand: has no effect in current tests
|
|
# add_offset = (operand < 0) ? 0 : 1
|
|
operand *= -1 if (operand < 0)
|
|
raise "offset too large (max 4095) #{arg} #{inspect}" if (@operand.abs > 4095)
|
|
end
|
|
operand
|
|
end
|
|
def instuction_class
|
|
0b01 # OPC_MEMORY_ACCESS
|
|
end
|
|
def add_offset
|
|
@attributes[:add_offset] ? 0 : 1
|
|
end
|
|
|
|
def byte_access
|
|
opcode.to_s[-1] == "b" ? 1 : 0 #B (byte) flag
|
|
end
|
|
end
|
|
end
|