Reading raw data from a file

Questions
1

Searching the forum I have found several references to reading in data from a file built directly within Codea and saved out as global data.

I have a file which I think is stored as Hex and I’d like to read it in to see if I can manipulate the data. I tried to read it as a png File by renaming the file to .png but Codea must detect file types from their structure so I can’t even read the data into memory. Any ideas?

2

@Bri_G I have a project that displays the contents of a hex file, but I don’t have time right now. I’ll find it, cut it down to just displaying the file and post it later.

3

@dave1707 - no pressure/rush, currently trying to read file on other systems. Would like to see your code - appreciated.

4

@Bri_G Here’s the program to read a hex file. Change the fileName to the file you want to read. Change the size for the number of bytes you want to read. The program will print any ascii character as that character and will print any non ascii characters as (##) where ## is the hex value of that character. This is set to read a file from the Dropbox folder. Let me know if this works for what you want otherwise I can do something else.

function setup()  
    fileName="Crash.png"
    size=1000

    file = os.getenv("HOME").."/Documents/Dropbox.assets/"..fileName
    readBinary()
end

function readBinary()
    xx={}
    binaryFile=io.open(file,"rb")
    if binaryFile then
        binaryData=binaryFile:read(size)
        binaryFile:close()
        for i=1,#binaryData do
            ch=binaryData:byte(i)
            if ch>=32 and ch<=126 then
                table.insert(xx,string.char(ch))
            else
                table.insert(xx,string.format("(%02x)",ch))
            end
        end
        print(table.concat(xx))
    else
        print("Invalid file name or file not found")
    end
end
5

@dave1707 - thanks for that, managed to read the file and play around with your code to capture the data in a reasonable format. Now the hard work in deciphering it!! Thanks for the help.