# 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/syntax/common'

module Ronin
  module Code
    module ASM
      module Syntax
        #
        # Handles emitting Assembly source code in ATT syntax.
        #
        class ATT < Common

          # Data sizes and their instruction mnemonics
          WIDTHS = {
            8 => 'q',
            4 => 'l',
            2 => 'w',
            1 => 'b',
            nil => ''
          }

          #
          # Emits a register.
          #
          # @param [Register] reg
          #   The register.
          #
          # @return [String]
          #   The register name.
          #
          def self.emit_register(reg)
            "%#{reg.name}"
          end

          #
          # Emits an immediate operand.
          #
          # @param [ImmediateOperand] op
          #   The operand.
          #
          # @return [String]
          #   The formatted immediate operand.
          #
          def self.emit_immediate_operand(op)
            "$#{emit_integer(op.value)}"
          end

          #
          # Emits a memory operand.
          #
          # @param [MemoryOperand] op
          #   The operand.
          #
          # @return [String]
          #   The formatted memory operand.
          #
          def self.emit_memory_operand(op)
            asm = emit_register(op.base)

            if op.index
              asm << ',' << emit_register(op.index)
              asm << ',' << op.scale.to_s if op.scale > 1
            end

            asm = "(#{asm})"
            asm = emit_integer(op.offset) + asm if op.offset != 0

            return asm
          end

          #
          # Emits multiple operands.
          #
          # @param [Array<ImmediateOperand, MemoryOperand, Register, Symbol>] ops
          #   The Array of operands.
          #
          # @return [String]
          #   The formatted operands.
          #
          def self.emit_operands(ops)
            if ops.length > 1
              [*ops[1..-1], ops[0]].map { |op| emit_operand(op) }.join(",\t")
            else
              super(ops)
            end
          end

          #
          # Emits an instruction.
          #
          # @param [Instruction] ins
          #   The instruction.
          #
          # @return [String]
          #   The formatted instruction.
          #
          def self.emit_instruction(ins)
            line = emit_keyword(ins.name)

            unless ins.operands.empty?
              unless (ins.operands.length == 1 && ins.width == 1)
                line << WIDTHS[ins.width]
              end

              line << "\t" << emit_operands(ins.operands)
            end

            return line
          end

          #
          # Emits a section name.
          #
          # @param [Symbol] name
          #   The section name.
          #
          # @return [String]
          #   The formatted section name.
          #
          # @since 0.2.0
          #
          def self.emit_section(name)
            ".#{name}"
          end

          #
          # Emits the program's prologue.
          #
          # @param [Program] program
          #   The program.
          #
          # @return [String]
          #   The formatted prologue.
          #
          # @since 0.2.0
          #
          def self.emit_prologue(program)
            ".code#{BITS[program.arch]}"
          end

        end
      end
    end
  end
end