map.py

#!/usr/bin/env python3
# vim: set expandtab tabstop=4 shiftwidth=4:

import struct

# My seemingly-known room row start
start = 0x628C

# Rows to fill in
rows = 24

# How far up to fill in rows
row_offset = -11

# Amount of data in each row
row_data_len = 5*22*20

###
###
###

offset = start + (row_offset*row_data_len)
bytes_to_write = rows*row_data_len
print(f'Writing {rows} row(s) starting at offset 0x{offset:X} for length {bytes_to_write}')

with open('AnimalWell.sav', 'r+b') as df:
    df.seek(offset)
    for _ in range(bytes_to_write):
        df.write(b'\xFF')
    print(f'... ended at 0x{df.tell():X}')

    # Rather sick of doing this manually...
    print('Also turning off scanlines...')
    df.seek(0x75048)
    df.write(b'\12')

    # Fix checksum
    df.seek(0)
    data = df.read()
    total = 0
    for byte in data[:13] + data[14:]:
        total ^= byte
    if total == data[0xD]:
        print(f'No need to write checksum -- 0x{total:02X} is already correct')
    else:
        packed = struct.pack('<B', total)
        df.seek(0xD)
        df.write(packed)
        print(f'Wrote new checksum 0x{total:02X} (previous: 0x{data[0xD]:02X})')