66 lines
2.7 KiB
Python
66 lines
2.7 KiB
Python
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# NOTE: This script is test under Python 3.x
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__copyright__ = "Copyright (C) 2020 Nuvoton Technology Corp. All rights reserved"
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import sys
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import crcmod
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class UnpackImage:
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def __init__(self, pack_file_name, nocrc):
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self.img_list = []
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try:
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with open(pack_file_name, "rb") as pack_file:
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self.pack_data = pack_file.read()
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except (IOError, OSError) as err:
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print(f"Open {pack_file_name} failed")
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sys.exit(err)
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if self.pack_data[0:4] != b'\x20\x54\x56\x4e':
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print(f"{pack_file_name} marker check failed")
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sys.exit(0)
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print("Waiting for unpack Images ...")
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if nocrc == 0:
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print("check pack file crc32 ...")
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crc32_func = crcmod.predefined.mkCrcFun('crc-32')
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checksum = crc32_func(self.pack_data[8:])
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if checksum != int.from_bytes(self.pack_data[4:8], byteorder='little'):
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print(f"{pack_file_name} CRC check failed")
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sys.exit(0)
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self.image_cnt = int.from_bytes(self.pack_data[8:12], byteorder='little')
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# 1st image descriptor begins @ 0x10
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index = 0x10
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for _ in range(self.image_cnt):
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# Put the image length, offset ,attribute in list
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self.img_list.append([int.from_bytes(self.pack_data[index: index + 8], byteorder='little'),
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int.from_bytes(self.pack_data[index + 8: index + 16], byteorder='little'),
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int.from_bytes(self.pack_data[index + 16: index + 20], byteorder='little'),
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index + 24])
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index += int.from_bytes(self.pack_data[index: index + 8], byteorder='little') + 24 # 24 is image header
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if index % 16 != 0:
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index += 16 - (index & 0xF) # round to 16-byte align
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def img_count(self):
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return self.image_cnt
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def img_attr(self, index):
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if index < self.image_cnt:
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# No need to return the last entry, actual offset in image file.
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# And should return integers instead of list of integer here
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return self.img_list[index][0], self.img_list[index][1], self.img_list[index][2]
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else:
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print("Invalid image index")
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return 0, 0, 0
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def img_content(self, index, offset, size):
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if index >= self.image_cnt:
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print("Invalid image index")
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return ''
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if offset > self.img_list[index][0] or offset + size > self.img_list[index][0]:
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print("Invalid offset")
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return ''
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return self.pack_data[self.img_list[index][3] + offset: self.img_list[index][3] + offset + size]
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