Android Question Reading a data file 0-255

[ElliotHC]

Upon looking through the posts in order to find out how in B4A to download and read a file, I have noticed that there may be some issues when importing the data.

In my data file I have 0-255, many of these fall outside of the standard ASCII table, some would call it extended ASCII.

My hardware which is coded using a different Basic compiler, requires that I send it a 2k data bundle created as a file (e.g. 123.ABC) by a VB App I've written.

This data file contains bytes 0-255 in value and I need to read this file which is located on my webserver (http://mydomain.com/123.ABC).

The B4A App which does all the control of the hardware via bluetooth (which is working perfectly), also needs to be able to read the data file and pass it to the hardware through the transparent serial connection that I'm using..

So basically and in as simple form as possible, I need to read from the web location, load that data in to an array that I can parse with the B4A App and send to the hardware.

Erel has given me this example, but I am not sure how to implement it.

Dim lines As List = File.ReadList(...)
Dim s As String = File.ReadString(...)

Will that string give me access to the full 0-255 byte?

 

[sorex]

for plain data files you need to use the randomaccess library and readbytes().

 

[sorex]

This data file contains bytes 0-255 in value

my reply above is focussed on data being real bytes.
Does the quote above mean this? or is it stored as 240,13,167 text? then you can use file.readstring aswell.

 

[ElliotHC]

for plain data files you need to use the randomaccess library and readbytes().

So

If j.Success Then
        Log(j.GetString)
    End If

Would be

If j.Success Then
        Log(j.ReadBytes)
    End If

?

 

[ElliotHC]

my reply above is focussed on data being real bytes.
Does the quote above mean this? or is it stored as 240,13,167 text? then you can use file.readstring aswell.

My data is <123><0><255><etc..>

<this is a single byte value>

 

[sorex]

no, the first one is correct IF the data is plain text

 

[sorex]

check the 2nd example here if your file is binary > https://www.b4x.com/android/forum/threads/download-image-or-file-from-a-website.39412/#content

 

[DonManfred]

bytes in b4a are signed.

you can convert it to unsigned (0-255) with

Sub ToUnsigned(b As Byte) As Int
   Return Bit.And(0xFF, b)
End Sub

 

[ElliotHC]

bytes in b4a are signed.

you can convert it to unsigned (0-255) with

Sub ToUnsigned(b As Byte) As Int
   Return Bit.And(0xFF, b)
End Sub

Sub Download (Callback As Object, link As String) As HttpJob
    Dim j As HttpJob
    j.Initialize("", Callback)
    j.Download("http://mydomain.com/123.ABC")
    Return j
End Sub

Sub Button_Download_Click
    Wait For (Download(Me, "http://mydomain.com/123.ABC")) JobDone (j As HttpJob)
    If j.Success Then
        Log(j.GetString)
    End If
    j.Release
End Sub

I need to convert j above in to an array, then I can parse through that array and read the bytes as decimal values 0-255 as I need to decrypt it before sending it out to the hardware.
I've done all this already in a VB app using a BT serial interface, but of course it's working a little differently here in B4A.

 

[sorex]

download the file with the code in Erel's tutorial I posted above and then read it back in with readbyte into your array.

maybe the saving is not needed but I don't know if you can access the stream data like an array.

 

[ElliotHC]

Sub Button_Firmware_Click
    Dim job As HttpJob
    job.Initialize("j", Me)
    job.Download("http://mydomain.com/123.abc")
End Sub

Sub JobDone(job As HttpJob)
    If job.Success Then

        Log(job.GetString)
        
        
        For A1 = 0 To job.GetString.Length
            ' Need to load the array here
        Next

    Else
        Log("Error: " & job.ErrorMessage)
    End If
    job.Release
End Sub

Sub ToUnsigned(b As Byte) As Int
    Return Bit.And(0xFF, b)
End Sub

Something like this?

Although I'm not sure how I use your code in the jobdone sub

 

[DonManfred]

It is really helpful to totally hide all relevant infos.

What exactly do you get from the call?

Need to load the array here

The text from job.getstring is a STRING. There is no array.

 

[sorex]

good news... you can access the stream data at once.

this is in B4J

Sub Process_Globals
    Private fx As JFX
 Dim bytes(10000) As Byte
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    Dim job As HttpJob
    job.Initialize("j", Me)
    job.Download("http://server-sql/123.abc")
End Sub


Sub JobDone(job As HttpJob)
    If job.Success Then
     job.GetInputStream.ReadBytes(bytes,0,job.GetInputStream.BytesAvailable)
     For x=0 To 10'job.GetInputStream.BytesAvailable-1
       Log( Bit.And(bytes(x),255) )
     Next                                       
   Else
     Log("Error: " & job.ErrorMessage)
   End If
    job.Release
End Sub

 

[ElliotHC]

This Works.

Sub JobDone(job As HttpJob)
    If job.Success Then

        Log(job.GetString)
        Dim S As String
        s = job.GetString
        Dim bytes() As Byte = s.GetBytes("UTF8")

        For A1 = 0 To job.GetString.Length - 1
            Log(bytes(A1))
        Next

    Else
        Log("Error: " & job.ErrorMessage)
    End If
    job.Release
End Sub

 

[ElliotHC]

good news... you can access the stream data at once.

this is in B4J

Sub Process_Globals
    Private fx As JFX
 Dim bytes(10000) As Byte
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    Dim job As HttpJob
    job.Initialize("j", Me)
    job.Download("http://server-sql/123.abc")
End Sub


Sub JobDone(job As HttpJob)
    If job.Success Then
     job.GetInputStream.ReadBytes(bytes,0,job.GetInputStream.BytesAvailable)
     For x=0 To 10'job.GetInputStream.BytesAvailable-1
       Log( Bit.And(bytes(x),255) )
     Next                                      
   Else
     Log("Error: " & job.ErrorMessage)
   End If
    job.Release
End Sub

Yes, the code I posted only works with ASCII. Let me try that.

 

[DonManfred]

bytes(A1)

if this send -127 - 127 values to the log then you need to use ToUnsigned on the byte.

Log(ToUnsigned(bytes(A1)))

 

[ElliotHC]

        job.GetInputStream.ReadBytes(bytes,0,job.GetInputStream.BytesAvailable)

        For x = 0 To job.GetInputStream.BytesAvailable - 1
            Log( Bit.And(bytes(x),255))
            Log(ToUnsigned(bytes(x)))
        Next

So in both cases I'm not seeing values that aren't text. I have a <9> in my file in between the characters Any ideas?

 

[DonManfred]

You are still HIDING the result you get! WHY?
Help us help you and post all relevant infos. I´m out for now. not interested to further trying to help

 

[ElliotHC]

Scrap that, Filezilla hadn't uploaded the modified data file although it said it had. Working nicely! Thanks guys.

 

[ElliotHC]

For some reason when I have F0 (240) it comes out as -16.. Any ideas? Looks like we are only working with 127

        Log(job.GetString)
       
        job.GetInputStream.ReadBytes(bytes,0,job.GetInputStream.BytesAvailable)

        For x = 0 To job.GetInputStream.BytesAvailable - 1
            'Log( Bit.And(bytes(x),255))
            'Log(ToUnsigned(bytes(x)))
            Log(bytes(x))
        Next