rubyx/lib/risc/text_writer.rb

232 lines
8.0 KiB
Ruby

module Risc
# To create a binary, we need a so called Text element. Bad name for what is the code
#
# Binary code is already created by the Machine (by translating risc to arm to binary)
#
# This class serves to write all the objects of the machine (wich also contain the code)
# into one stream or binary text object. This is then written to an ELF text section.
#
# A word about positions: The c world has a thing called position independent code, and
# baically we follw that idea. Code (ie jumps and constant loads) are all relative.
# But we have pointers. In C the linker takes care of bending those, we have to
# do that ourselves, in write_ref. That's why we need the load adddess and basically
# we just add it to pointers.
class TextWriter
include Logging
log_level :info
MARKER = 0xBAD4C0DE
def initialize( machine)
@machine = machine
@load_at = 0x10054 # this is linux/arm
end
# objects must be written in same order as positioned by the machine, namely
# - intial jump
# - all objects
# - all BinaryCode
def write_as_string
@stream = StringIO.new
write_init(@machine.binary_init)
write_debug
write_objects
write_code
log.debug "Assembled 0x#{stream_position.to_s(16)} bytes"
return @stream.string
end
# debugging loop to write out positions (in debug)
def write_debug
@machine.objects.each do |id , objekt|
next if objekt.is_a?(Risc::Label)
log.debug "Linked #{objekt.class}:0x#{objekt.object_id.to_s(16)} at 0x#{Position.position(objekt).to_s(16)} / 0x#{objekt.padded_length.to_s(16)}"
end
end
# Write all the objects
def write_objects
# then the objects , not code yet
@machine.objects.each do | id, objekt|
next if objekt.is_a? Parfait::BinaryCode
next if objekt.is_a? Risc::Label # ignore
write_any( objekt )
end
end
# Write the BinaryCode objects of all methods to stream.
# Really like any other object, it's just about the ordering
def write_code
@machine.objects.each do |id, method|
next unless method.is_a? Parfait::TypedMethod
binary = method.binary
while(binary) do
write_any( binary )
binary = binary.next
end
end
end
# Write any object just logs a bit and passes to write_any_out
def write_any( obj )
write_any_log( obj , "Write")
if @stream.length != Position.position(obj)
raise "Write #{obj.class}:0x#{obj.object_id.to_s(16)} at 0x#{stream_position.to_s(16)} not 0x#{Position.position(obj).to_s(16)}"
end
write_any_out(obj)
write_any_log( obj , "Wrote")
Position.position(obj)
end
def write_any_log( obj , at)
log.debug "#{at} #{obj.class}:0x#{obj.object_id.to_s(16)} at stream 0x#{stream_position.to_s(16)} pos:0x#{Position.position(obj).to_s(16)} , len:0x#{obj.padded_length.to_s(16)}"
end
# Most objects are the same and get passed to write_object
# But Strings and BinaryCode write out binary, so they have different methods (for now)
def write_any_out(obj)
case obj
when Parfait::Word, Symbol
write_String obj
when Parfait::BinaryCode
write_BinaryCode obj
when Parfait::Data4
write_data2 obj
else
write_object obj
end
end
# write type of the instance, and the variables that are passed
# variables ar values, ie int or refs. For refs the object needs to save the object first
def write_object( object )
write_object_check(object)
obj_written = write_object_variables(object)
log.debug "instances=#{object.get_instance_variables.inspect} mem_len=0x#{object.padded_length.to_s(16)}"
indexed_written = write_object_indexed(object)
log.debug "type #{obj_written} , total #{obj_written + indexed_written} (array #{indexed_written})"
log.debug "Len = 0x#{object.get_length.to_s(16)} , inst =0x#{object.get_type.instance_length.to_s(16)}" if object.is_a? Parfait::Type
pad_after( obj_written + indexed_written )
Position.position(object)
end
def write_object_check(object)
log.debug "Write object #{object.class} #{object.inspect[0..100]}"
#Only initially created codes are collected. Binary_init and method "tails" not
if !@machine.objects.has_key?(object.object_id) and !object.is_a?(Parfait::BinaryCode)
log.debug "Object at 0x#{Position.position(object).to_s(16)}:#{object.get_type()}"
raise "Object(0x#{object.object_id.to_s(16)}) not linked #{object.inspect}"
end
end
def write_object_indexed(object)
written = 0
if( object.is_a? Parfait::List)
object.each do |inst|
write_ref_for(inst)
written += 4
end
end
written
end
def write_object_variables(object)
@stream.write_signed_int_32( MARKER )
written = 0 # compensate for the "secret" marker
object.get_instance_variables.each do |var|
inst = object.get_instance_variable(var)
#puts "Nil for #{object.class}.#{var}" unless inst
inst = nil if [:cpu_instructions , :risc_instructions].include?(var)
write_ref_for(inst)
written += 4
end
written
end
def write_data2( code )
@stream.write_signed_int_32( MARKER )
write_ref_for( code.get_type )
log.debug "Data4 witten stream 0x#{@stream.length.to_s(16)}"
end
# first jump, treated as a binary code, but this one needs
# the actual jump as the first
def write_init( code )
code.each_word do |word|
@stream.write_unsigned_int_32( word || 0 )
end
write_ref_for( code.next )
write_ref_for( code.get_type )
@stream.write_signed_int_32( MARKER )
log.debug "Init witten stream 0x#{@stream.length.to_s(16)}"
end
def write_BinaryCode( code )
@stream.write_signed_int_32( MARKER )
write_ref_for( code.get_type )
write_ref_for( code.next )
code.each_word do |word|
@stream.write_unsigned_int_32( word || 0 )
end
log.debug "Code16 witten stream 0x#{@stream.length.to_s(16)}"
end
def write_String( string )
if string.is_a? Parfait::Word
str = string.to_string
raise "length mismatch #{str.length} != #{string.char_length}" if str.length != string.char_length
end
str = string.to_s if string.is_a? Symbol
log.debug "#{string.class} is #{string} at 0x#{Position.position(string).to_s(16)} length 0x#{string.length.to_s(16)}"
write_checked_string(string , str)
end
def write_checked_string(string, str)
@stream.write_signed_int_32( MARKER )
write_ref_for( string.get_type ) #ref
@stream.write_signed_int_32( str.length ) #int
@stream.write str
pad_after(str.length + 8 ) # type , length *4 == 12
log.debug "String (0x#{string.length.to_s(16)}) stream 0x#{@stream.length.to_s(16)}"
end
def write_Symbol(sym)
return write_String(sym)
end
private
# write means we write the resulting address straight into the assembler stream
# object means the object of which we write the address
def write_ref_for object
case object
when nil
@stream.write_signed_int_32(0)
when Fixnum
@stream.write_signed_int_32(object)
else
@stream.write_signed_int_32(Position.position(object) + @load_at)
end
end
# pad_after is always in bytes and pads (writes 0's) up to the next 8 word boundary
def pad_after( length )
before = stream_position
pad = Padding.padding_for(length) - 4 # four is for the MARKER we write
pad.times do
@stream.write_unsigned_int_8(0)
end
after = stream_position
log.debug "padded 0x#{length.to_s(16)} with 0x#{pad.to_s(16)} stream #{before.to_s(16)}/#{after.to_s(16)}"
end
# return the stream length as hex
def stream_position
@stream.length
end
end
RxFile::Volotile.add(TextWriter , [:objects])
end