Verify sprite type 1 in TWG

chkspr1.py

# -*- coding: utf-8 -*-

import argparse
import struct
import os

parser = argparse.ArgumentParser(description='Verify sprite file.')
parser.add_argument('-f', required=True, help='sprite file', dest='spr')
args = parser.parse_args()

with open(args.spr, 'rb') as f:
  f.seek(0, os.SEEK_END)
  file_len = f.tell()
  f.seek(0, os.SEEK_SET)

  bytes = f.read(0x40)
  assert b'New Fast&Compress Sprite Ver3.0 for 13h mode!!!. SOFTMAX(C)1994.' == bytes

  f.seek(2, os.SEEK_CUR)

  # total number of sprites
  bytes = f.read(2)
  bytes = struct.unpack('<H', bytes)
  num = bytes[0]

  # zero padding
  f.seek(60, os.SEEK_CUR)

  # each sprite data offset list 
  offsets = []
  for n in range(num):
    bytes = f.read(4)
    bytes = struct.unpack('<I', bytes)
    offsets.append(bytes[0])

  for ofs in offsets:
    f.seek(ofs, os.SEEK_SET)

    # total length of compressed pixel data
    bytes = f.read(4)
    bytes = struct.unpack('<I', bytes)
    len = bytes[0]

    # width of a sprite
    bytes = f.read(2)
    bytes = struct.unpack('<H', bytes)
    assert 320 >= bytes[0]

    # height of a sprite
    bytes = f.read(2)
    bytes = struct.unpack('<H', bytes)
    assert 200 >= bytes[0]

    # unknown
    f.seek(2, os.SEEK_CUR)
    f.seek(2, os.SEEK_CUR)

    buf = f.read(2)
    buf = struct.unpack('<H', buf)
    chunks = buf[0]
    
    l = 0
    for c in range(chunks):
      buf = f.read(2)
      buf = struct.unpack('<H', buf)
      blanks = buf[0]
      
      buf = f.read(1)
      buf = struct.unpack('<B', buf)
      i = buf[0]
      
      buf = f.read(1)
      buf = struct.unpack('<B', buf)
      j = buf[0]
      
      f.read(4 * i + j)
      
      l = l + 2 + 1 + 1 + 4 * i + j

    assert (l + 2) == length
    
  assert f.tell() == file_len