You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ppc_pdf2oplist.rb
    path of file: ./repos/grinder/node/lib/metasm/misc
    
    the code of the file until where you have to start completion: #    This file is part of Metasm, the Ruby assembly manipulation suite
#    Copyright (C) 2006-2009 Yoann GUILLOT
#
#    Licence is LGPL, see LICENCE in the top-level directory
#
# parses the PPC specification PDF to generate the opcode list
#

require 'pdfparse'

$field_mask = {}
$field_shift = {}
$opcodes = []
def make_instr(bins, bits, text)
	# calc bitfields length from their offset
	last = 32
	bitlen = []
	bits.reverse_each { |bit|
		bitlen.unshift last-bit
		last = bit
	}

	# the opcode binary value (w/o fie
    
def make_instr(bins, bits, text)
	# calc bitfields length from their offset
	last = 32
	bitlen = []
	bits.reverse_each { |bit|
		bitlen.unshift last-bit
		last = bit
	}

	# the opcode binary value (w/o fields)
	bin = 0
	fields = []

	# parse the data
	bins.zip(bits, bitlen).each { |val, off, len|
		off = 32-(off+len)
		msk = (1 << len) - 1
		case val
		when '/', '//', '///'	# reserved field, value unspecified
		when /^\d+$/; bin |= val.to_i << off	# constant field
		when /^[A-Za-z]+$/
			fld = val.downcase.to_sym
			fld = "#{fld}_".to_sym while $field_mask[fld] and ($field_mask[fld] != msk or $field_shift[fld] != off)
			fields << fld
			$field_mask[fld] ||= msk
			$field_shift[fld] ||= off
		end