# frozen_string_literal: true
#
# ronin-code-asm - A Ruby DSL for crafting Assembly programs and shellcode.
#
# Copyright (c) 2007-2022 Hal Brodigan (postmodern.mod3 at gmail.com)
#
# ronin-code-asm is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# ronin-code-asm is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with ronin-code-asm.  If not, see <https://www.gnu.org/licenses/>.
#

require 'ronin/code/asm/memory_operand'

module Ronin
  module Code
    module ASM
      #
      # Represents a Register.
      #
      class Register < Struct.new(:name, :width, :general)

        #
        # Initializes a register.
        #
        # @param [Symbol] name
        #   The register name.
        #
        # @param [Integer] width
        #   The width of the register.
        #
        # @param [Boolean] general
        #   Specifies whether the register is a General Purpose Register (GPR).
        #
        def initialize(name,width,general=false)
          super(name,width,general)
        end

        #
        # Adds an offset to the value within the register and dereferences the
        # address.
        #
        # @param [MemoryOperand, Register, Integer] offset
        #   The offset to add to the value of the register.
        #
        # @return [MemoryOperand]
        #   The new Memory Operand.
        #
        # @raise [TypeError]
        #   the `offset` was not an {MemoryOperand}, {Register} or Integer.
        #
        def +(offset)
          case offset
          when MemoryOperand
            MemoryOperand.new(self,offset.offset,offset.index,offset.scale)
          when Register
            MemoryOperand.new(self,0,offset)
          when Integer
            MemoryOperand.new(self,offset)
          else
            raise(TypeError,"offset was not an MemoryOperand, Register or Integer")
          end
        end

        #
        # Substracts from the value within the register and dereferences the
        # address.
        #
        # @param [Integer] offset
        #   The value to subtract from the value of the register.
        #
        # @return [MemoryOperand]
        #   The new Memory Operand.
        #
        def -(offset)
          MemoryOperand.new(self,-offset)
        end

        #
        # Multiples the value within the register.
        #
        # @param [Integer] scale
        #   The scale to multiply the value within register by.
        #
        # @return [MemoryOperand]
        #   The new Memory Operand.
        #
        def *(scale)
          MemoryOperand.new(nil,0,self,scale)
        end

        #
        # @return [String]
        #   The register's name.
        #
        def to_s
          self.name.to_s
        end

      end
    end
  end
end