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