python3.9 'byte' data handling

Question

I'm working on a 6809 python processor emulator for educational purposes.

I have a short binary file on the hard drive. The data is raw assembler output for a Motorola MC6809 that has the following contents:

0000300000338cfd4f5f10eec9100012126ec90010adc900186e4c12124cb10255270339121232624f5cf1025527046e4c12126ec4ff00000000

Actual code data:

338cfd4f5f10eec9100012126ec90010adc900186e4c12124cb10255270339121232624f5cf1025527046e4c12126ec4

Using python3.9 how do I get this into a list mem[] as either:

mem[00,00,30,00,00,33,8c,fd,4f,5f,...]

I suspect since ascii characters are involved here quotes would be needed

or

mem[0x00,0x00,0x30,0x00,0x00,0x33,0x8c,0xfd,0x4f,0x5f,...]

all I can seem to do is get the data back as

mem[b'00',b'00',b'30',b'00',b'00',b'33'.b'8c',b'fe',b'4f',b'5f',...]

But I can't seem to typecast these byte values into anything usable.

I've tried a half a dozen methods, with some questionable/unusable results.

Does this answer your question? [Reading a binary file with python](https://stackoverflow.com/questions/8710456/reading-a-binary-file-with-python) — bfris, Aug 26 '21 at 23:14
"a list mem[] " *what*? That doesn't make any sense in Python. What, **exactly** is the object you require? — juanpa.arrivillaga, Aug 27 '21 at 03:39
You need to tell us *precisely* what your input is, and *precisely* what you are trying to create. Otherwise, this isn't on-topic for StackOverflow. — juanpa.arrivillaga, Aug 27 '21 at 03:40
Sorry for the delay, all replies were helpful in one way or another. I'm one of those that started with BASIC and went straight to assembler at my job. The thing with working with assembly is that you can always get the result you need because you are doing the whole thing at the most primitive level. Then, worked my way back up with C, pascal, some Fortran and now python. Thank you all. — mwfarrell, Jun 13 '23 at 23:49

score 1 · Accepted Answer · answered Aug 27 '21 at 03:24

Your question implies that you have a file full of ASCII characters, but your self-answer contradicts that by converting single bytes into integers.

It turns out that bytes are already integers. All you need to do is convert the bytes that you read into a list. You could probably work with the bytes object directly, but who am I to judge.

with open("/home/me/Documents/Sources/procproject.BIN", "rb") as memin:
    mem = list(memin.read())

Yes, this is the answer. – juanpa.arrivillaga Aug 27 '21 at 03:42 — juanpa.arrivillaga, Aug 27 '21 at 03:42

score 0 · Answer 2 · answered Aug 27 '21 at 03:02

thank you for your time and replies
struct is not really a straight up simple method, but I found a rather interesting and simple way to get a byte array into a hex integer array

==========


    mem = []
    memin = open("/home/me/Documents/Sources/procproject.BIN", "rb")
    
    while True:
        mp = bytes(memin.read(1))
        if mp == b'':
            break
        mem.append(hex(int.from_bytes(mp, 'big'))) #this is the magic#
    memin.close()
    mem=mem[5:]
    mem = mem[:-5]

==========
works like a charm

That is not a "hex integer" array. This is a `list` of string objects. Not sure why you would think this is useful. You should really carefully consider @MarkRansom answer — juanpa.arrivillaga, Aug 27 '21 at 03:41

python3.9 'byte' data handling

2 Answers2