56 lines
1.5 KiB
Python
Executable File
56 lines
1.5 KiB
Python
Executable File
#!/usr/bin/env python3
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# SPDX-License-Identifier: GPL-2.0+
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"""
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Simple tool to swap the byte endianness of a binary file.
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"""
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import argparse
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import io
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def parse_args():
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"""Parse command line arguments."""
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description = "Swap endianness of given input binary and write to output binary."
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parser = argparse.ArgumentParser(description=description)
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parser.add_argument("input_bin", type=str, help="input binary")
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parser.add_argument("output_bin", type=str, help="output binary")
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parser.add_argument("-c", action="store", dest="chunk_size", type=int,
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default=io.DEFAULT_BUFFER_SIZE, help="chunk size for reading")
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return parser.parse_args()
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def swap_chunk(chunk_orig):
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"""Swap byte endianness of the given chunk.
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Returns:
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swapped chunk
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"""
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chunk = bytearray(chunk_orig)
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# align to 4 bytes and pad with 0x0
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chunk_len = len(chunk)
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pad_len = chunk_len % 4
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if pad_len > 0:
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chunk += b'\x00' * (4 - pad_len)
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chunk[0::4], chunk[1::4], chunk[2::4], chunk[3::4] =\
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chunk[3::4], chunk[2::4], chunk[1::4], chunk[0::4]
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return chunk
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def main():
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args = parse_args()
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with open(args.input_bin, "rb") as input_bin:
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with open(args.output_bin, "wb") as output_bin:
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while True:
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chunk = bytearray(input_bin.read(args.chunk_size))
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if not chunk:
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break
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output_bin.write(swap_chunk(chunk))
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if __name__ == '__main__':
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main()
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