rubyx/lib/arm/stack_instruction.rb
2014-05-03 22:18:04 +03:00

59 lines
1.7 KiB
Ruby

require_relative "instruction"
module Arm
# ADDRESSING MODE 4
class StackInstruction < Vm::StackInstruction
def initializ(opcode , condition_code , update_status , args)
super(opcode , condition_code , update_status , args)
@update_status_flag= 0
@rn = reg "r0" # register zero = zero bit pattern
# downward growing, decrement before memory access
# official ARM style stack as used by gas
@write_base = 1
if (opcode == :push)
@pre_post_index = 1
@up_down = 0
@is_pop = 0
else #pop
@pre_post_index = 0
@up_down = 1
@is_pop = 1
end
end
attr_accessor :pre_post_index, :up_down,
:update_status_flag, :write_base, :is_pop, :rn
def assemble(io)
build
instuction_class = 0b10 # OPC_STACK
cond = @condition_code.is_a?(Symbol) ? COND_CODES[@condition_code] : @condition_code
rn = reg "sp" # sp register
#assemble of old
val = operand
val |= (rn.bits << 16)
val |= (is_pop << 16+4) #20
val |= (write_base << 16+4+ 1)
val |= (update_status_flag << 16+4+ 1+1)
val |= (up_down << 16+4+ 1+1+1)
val |= (pre_post_index << 16+4+ 1+1+1+1)#24
val |= (instuction_class << 16+4+ 1+1+1+1 +2)
val |= (cond << 16+4+ 1+1+1+1 +2+2)
io.write_uint32 val
end
private
# Build representation for source value
def build
if (args.is_a?(Array))
@operand = 0
args.each do |reg |
@operand |= (1 << reg.bits)
end
else
raise Asm::AssemblyError.new("invalid operand argument #{args.inspect}")
end
end
end
end