Extract weights from Wii Fit

wiifit.py

#!/usr/bin/python
# Based on http://www.kellbot.com/2010/05/extracting-graphing-wii-fit-data/
#
# updated for python3
#
# Good references:
#   http://jansenprice.com/blog?id=9-Extracting-Data-from-Wii-Fit-Plus-Savegame-Files
#   http://stackoverflow.com/questions/616249/wii-fit-data-format
#
# Instructions to use this:
#
# 1. Download the data from the Wii to an SD card.
# 2. Build tachtig, needed to decrypt the data file.
#    $ sudo apt-get install openssl libssl-dev
#    $ git clone git://git.infradead.org/users/segher/wii.git
#    $ cd wii
#    $ make
#    Ignore the tons of warnings, just as long as it created tachtig. Double
#    check with:
#    $ ls -l tachtig
#    $ cd ..
# 3. Install the keys needed to decrypt the file
#    $ mkdir ~/.wii
#    $ echo ab01b9d8e1622b08afbad84dbfc2a55d | xxd -r -p - ~/.wii/sd-key
#    $ echo 216712e6aa1f689f95c5a22324dc6a98 | xxd -r -p - ~/.wii/sd-iv
#    $ echo 0e65378199be4517ab06ec22451a5793 | xxd -r -p - ~/.wii/md5-blanker
# 4. Decrypt it:
#    $ wii/tachtig [SD_CARD/private/wii/title/RFPE/]data.bin
#    That should create a directory with one or more .dat files, likely either
#    called RPHealth.dat or FitPlus0.dat
# 5. Extract the contents by running this script:
#    $ chmod +x wiifit.py
#    $ ./wiifit.py <location of .dat file>
# 6. Do whatever you want with the resulting WiiFit_<name>.csv file.

from __future__ import division
import csv
import struct
import string
import sys

# Path to WiiFit data file
file_name = sys.argv[1] if len(sys.argv) > 1 else 'RPHealth.dat'

# Adjust based on what the wii took off for each recording, in Kg.
weight_adjustment = float(sys.argv[2]) if len(sys.argv) > 2 else 0.0

# Each record is 0x9271 bytes long
record_length = 0x9281

with open(file_name, 'rb') as in_file:
    # Iterate through each Mii.
    for record_start in range(0, record_length * 100, record_length):
        # Go to the start of the current record.
        in_file.seek(record_start)

        # Read the first 30 bytes (header + name).
        line = in_file.read(30)

        # For some reason names are stored as N a m e instead of Name.
        # Throw away the header and any extranous spaces.
        data = struct.unpack('<9xcxcxcxcxcxcxcxcxcxcxc', line)

        #print(data)

        # Condense our unpacked characters into a string.
        wf_name = b"".join(data).decode().strip('\0')

        # my file has an empty record before last one, 
        # so i used continue to skip over
        # this unfortunately fails once it gets past the last record

        if not wf_name:
            print("Skipping this entry, seems to be blank record")
            continue
            #break

        print( 'Found', wf_name)

        # Open a new CSV file for this person.
        with open('WiiFit_%s.csv' % wf_name, 'w') as out_file:
            writer = csv.writer(out_file, delimiter=',', quotechar="'", quoting=csv.QUOTE_MINIMAL)
            writer.writerow(['Date', 'Weight', 'BMI', 'Balance'])

            # Weight data starts 0x38a1 bytes into the record.
            in_file.seek(record_start + 0x38a1)

            # Loop through the record data until it starts coming up blank.
            while True:
                # Each line is 21 bytes. We only care about the first bit.
                line = in_file.read(21)

        #        print("parsing" , line)

                # 4 bytes of hex-packed date followed by three sets of 2 bytes
                # representing weight, BMI, and balance.
        #        print(struct.unpack('>i3H',line[0:10]))

                packed_date, weight, bmi, balance = struct.unpack('>i3H', line[0:10])

                # Unpack the date: http://stackoverflow.com/questions/719129/datetime-hex-format
                year   = packed_date >> 20 & 0x7ff
                month  = (packed_date >> 16 & 0xf) + 1
                day    = packed_date >> 11 & 0x1f
                hour   = packed_date >> 6 & 0x1f
                minute = packed_date & 0x3f
                second = 0

                if year == 0:
                    break

                date = '%s-%02d-%02d %02d:%02d:%02d' % (year, month, day, hour, minute, second)
                writer.writerow([date, weight_adjustment + (weight / 10), bmi / 100, balance / 10])