devmem : add file saving

[psolyca]

Just a usefull thing for myself I share.

Feature added : As the title says, add the possibility to save the read values to a file.

[kylemanna]

I like the idea and the implementation looks clean!

I wonder though if it could be generalized a bit? What if it was updated to something like --binary and wrote to sys.stdout and the user could consider the following invocations:

Write to binary file:

$ devmem.py --binary -r 0x12345678 > file.bin

Write to another program for processing:

$ devmem.py --binary -r 0x12345678 | hexdump -C
$ devmem.py --binary -r 0x12345678 | path/to/memory_parser.py

This seems more flexible? What do you think?

[psolyca]

Yes of course.
I did not think of this way.

Maybe it will work better, cause finally I had to make a C program to dump the memory of my platform, ARM Cortex-A9, cause this python script freeze and/or never finalize.
I have more than 19771544 bytes to dump, in C it is done in 4-5s.

[psolyca]

@kylemanna Should be ok.

I have tested it and it works.
BTW, on my platform for 19771544 bytes long, I have a MemoryError on line 151.

[kylemanna]

I created MR #13 with a lot of improvements and a --binary output flag, can you check that out? I think it's also much faster.

Example using a file:

$ dd if=/dev/urandom count=1 bs=19771544 >! test2.bin
$ sha1sum test2.bin
2a69b263449ec99a5bcb04a670cd3b9b689d3f00  test2.bin
$ time (python3 -m devmem -s 4 -n 4942886 -r 0 -m test2.bin -b  | sha1sum )
2a69b263449ec99a5bcb04a670cd3b9b689d3f00  -

real    0.18s
user    0.15s
sys     0.04s