163 lines
4.1 KiB
Ruby
163 lines
4.1 KiB
Ruby
require 'asm/arm_assembler'
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require 'asm/instruction'
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require 'asm/generator_label'
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require 'asm/nodes'
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require 'stream_reader'
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require 'stringio'
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require "asm/string_literal"
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module Asm
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class ArmAssembler
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%w(r0 r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11 r12
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r13 r14 r15 a1 a2 a3 a4 v1 v2 v3 v4 v5 v6
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rfp sl fp ip sp lr pc
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).each { |reg|
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define_method(reg) {
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Asm::Register.new(reg)
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}
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}
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def initialize
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@values = []
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@position = 0 # marks not set
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@labels = []
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@string_table = {}
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end
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attr_reader :values , :position
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def instruction(name, *args)
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opcode = name.to_s
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arg_nodes = []
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args.each { |arg|
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if (arg.is_a?(Asm::Register))
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arg_nodes << arg
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elsif (arg.is_a?(Integer))
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arg_nodes << Asm::NumLiteral.new(arg)
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elsif (arg.is_a?(String))
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arg_nodes << add_string(arg)
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elsif (arg.is_a?(Symbol))
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arg_nodes << Asm::Label.new(arg.to_s)
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elsif (arg.is_a?(Asm::GeneratorLabel))
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arg_nodes << arg
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else
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raise 'Invalid argument `%s\' for instruction' % arg.inspect
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end
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}
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add_value Asm::Instruction.new(opcode , arg_nodes)
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end
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%w(adc add and bic eor orr rsb rsc sbc sub mov mvn cmn cmp teq tst b bl bx
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push pop swi str strb ldr ldrb
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).each { |inst|
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define_method(inst) { |*args|
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instruction inst.to_sym, *args
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}
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define_method(inst+'s') { |*args|
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instruction (inst+'s').to_sym, *args
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}
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%w(al eq ne cs mi hi cc pl ls vc lt le ge gt vs
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).each { |cond_suffix|
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define_method(inst+cond_suffix) { |*args|
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instruction (inst+cond_suffix).to_sym, *args
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}
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define_method(inst+'s'+cond_suffix) { |*args|
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instruction (inst+'s'+cond_suffix).to_sym, *args
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}
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}
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}
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def assemble_to_string
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#put the strings at the end of the assembled code.
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# adding them will fix their position and make them assemble after
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@string_table.values.each do |data|
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add_value data
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end
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io = StringIO.new
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assemble(io)
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io.string
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end
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def add_string str
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value = @string_table[str]
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return value if value
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data = Asm::StringLiteral.new(str)
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@string_table[str] = data
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end
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def strings
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@string_table.values
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end
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def add_value(val)
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val.at(@position)
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length = val.length
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@position += length
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@values << val
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end
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def label
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label = Asm::GeneratorLabel.new(self)
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@labels << label
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label
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end
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def label!
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label.set!
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end
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def assemble(io)
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@values.each do |obj|
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obj.assemble io, self
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end
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end
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end
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# Relocation constants
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# Note that in this assembler, a relocation simply means any
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# reference to a label that can only be determined at assembly time
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# or later (as in the normal meaning)
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R_ARM_PC24 = 0x01
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R_ARM_ABS32 = 0x02
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# Unofficial (cant be used for extern relocations)
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R_ARM_PC12 = 0xF0
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def self.write_resolved_relocation(io, addr, type)
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case type
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when R_ARM_PC24
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diff = addr - io.tell - 8
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if (diff.abs > (1 << 25))
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raise Asm::AssemblyError.new('offset too large for R_ARM_PC24 relocation')
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end
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packed = [diff >> 2].pack('l')
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io << packed[0,3]
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when R_ARM_ABS32
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packed = [addr].pack('l')
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io << packed
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when R_ARM_PC12
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diff = addr - io.tell - 8
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if (diff.abs > 2047)
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raise Asm::AssemblyError.new('offset too large for R_ARM_PC12 relocation')
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end
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val = diff.abs
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sign = (diff>0)?1:0
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curr = io.read_uint32
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io.seek(-4, IO::SEEK_CUR)
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io.write_uint32 (curr & ~0b00000000100000000000111111111111) |
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val | (sign << 23)
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else
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raise 'unknown relocation type'
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end
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end
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end
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