Sha256: f706898b92e1fbfe09a78210a155680941c64976f41ef148017de097edef5d7a
Contents?: true
Size: 1.36 KB
Versions: 13
Compression:
Stored size: 1.36 KB
Contents
#!/usr/bin/env ruby -w
# encoding: UTF-8
#
# = CRC16.rb -- Fit4Ruby - FIT file processing library for Ruby
#
# Copyright (c) 2014, 2015, 2016, 2017, 2018
# by Chris Schlaeger <cs@taskjuggler.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
module Fit4Ruby
module CRC16
def write_crc(io, start_pos, end_pos)
# Compute the checksum over the data section of the file and append it
# to the file. Ideally, we should compute the CRC from data in memory
# instead of the file data.
crc = compute_crc(io, start_pos, end_pos)
io.seek(end_pos)
BinData::Uint16le.new(crc).write(io)
crc
end
def compute_crc(io, start_pos, end_pos)
crc_table = [
0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401,
0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400
]
io.seek(start_pos)
crc = 0
while io.pos < end_pos
if io.eof?
raise IOError, "Premature end of file"
end
byte = io.readbyte
0.upto(1) do |i|
tmp = crc_table[crc & 0xF]
crc = (crc >> 4) & 0x0FFF
crc = crc ^ tmp ^ crc_table[(byte >> (4 * i)) & 0xF]
end
end
crc
end
end
end
Version data entries
13 entries across 13 versions & 1 rubygems