lib/ronin/code/asm/memory_operand.rb
# frozen_string_literal: true
#
# ronin-code-asm - A Ruby DSL for crafting Assembly programs and shellcode.
#
# Copyright (c) 2007-2024 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/register'
module Ronin
module Code
module ASM
#
# Represents a Memory Operand.
#
# @see http://asm.sourceforge.net/articles/linasm.html#Memory
#
class MemoryOperand < Struct.new(:base, :offset, :index, :scale, :width)
#
# Creates a new Memory Operand.
#
# @param [Register, nil] base
# The base of the value.
#
# @param [Integer] offset
# The fixed offset to add to the `base`.
#
# @param [Register, nil] index
# The variable index to multiple by `scale`, then add to `base.
#
# @param [Integer] scale
# The scale to multiple `index` by.
#
# @param [Integer, nil] width
# The optional width of the memory operand.
#
# @raise [TypeError]
# `base` or `index` was not a {Register} or `nil`.
#
def initialize(base=nil,offset=0,index=nil,scale=1,width=nil)
unless (base.nil? || base.kind_of?(Register))
raise(TypeError,"base must be a Register or nil")
end
unless offset.kind_of?(Integer)
raise(TypeError,"offset must be an Integer")
end
unless (index.nil? || index.kind_of?(Register))
raise(TypeError,"index must be a Register or nil")
end
unless scale.kind_of?(Integer)
raise(TypeError,"scale must be an Integer")
end
if base
width ||= base.width
end
super(base,offset,index,scale,width)
end
#
# Adds to the offset of the Memory Operand.
#
# @param [Integer] offset
# The offset to add to the Memory Operand.
#
# @return [MemoryOperand]
# The new Memory Operand.
#
def +(offset)
MemoryOperand.new(
self.base,
self.offset + offset,
self.index,
self.scale,
self.width
)
end
#
# Subtracts from the offset of the Memory Operand.
#
# @param [Integer] offset
# The offset to subject from the Memory Operand.
#
# @return [MemoryOperand]
# The new Memory Operand.
#
def -(offset)
MemoryOperand.new(
self.base,
self.offset - offset,
self.index,
self.scale,
self.width
)
end
end
end
end
end