Kye's fat driver - how to handle errors?

pik33 · 2012-06-16 22:57

Most of functions included in this driver returns strings instead of error codes.

For example, this:

c:=\fat.listentry(string("test"))

returs string "TEST" if there is a file called "TEST" on disk, or it aborts and returns string "Entry Not Found", if not.

Is it any method which can tell me if this function aborted or not? I patched this driver adding two functions:

pub geterror
result:=errorNumberFlag

pub reseterror
errornumberflag:=0

so now I can do this like

fat.reseterror
c:=\fat.listentry(string("test"))
if fat.geterror<>0
  vga.writeln(c)  
 'rest of error handling code. File doesn't exist so create one now and fill with data

and if fat.geterror==0 I can open my file and read the data from it

How can I do this without this patch I applied to the fat driver?

Dr_Acula · 2012-06-17 01:10

I used this code to print an error and then hang the program if a file is not found

PUB OpenFileRead(stringptr) ' open a file for reading and display a message if it fails
   result := \fat.openfile(stringptr,"R")
   if fat.partitionerror <> 0                           ' failed to find the file
     Text(stringptr)                         ' print the filename
     Text(result)                            ' print the error message
     repeat                                             ' stop the program

Is this what you need to do?

pik33 · 2012-06-17 03:18

Yes, I didn't notice that function in the file so I patched it with my own.

I want to open a file if it exists and read data from it, if not, I want to create a new one with this name and fill it with data..

I did it that way:

first added these two function to the fat driver:

pub geterror
result:=errorNumberFlag

pub reseterror
errornumberflag:=0

and then use it:

i:=0
fat.reseterror
c:=\fat.listentry(string("dmplist.dat"))
if fat.geterror<>0
  c:=\fat2.newfile(string("dmplist.dat"))

Now I can do it like this (?)

i:=0
fat.reseterror
c:=\fat.listentry(string("dmplist.dat"))
if fat.partitionerror<>0
  c:=\fat2.newfile(string("dmplist.dat"))

and use unpatched driver...

Kye · 2012-06-17 09:37

The function "fat.partitionError" returns an non zero where the non zero number is the error code which you can match to an error code in the top constant section of the driver. After you call the fat.partitionError function it clears the error. So, it's like the two functions you just added. But all in one.

Please see Parallax semiconductor an006 http://www.parallaxsemiconductor.com/an006.

....

So I think what you want to do is done like this:

temp := \fat.openFile(string("DMPLIST.DAT"), "R")

if(fat.partitionError == fat#Entry_Not_Found)
  temp := \fat.newFile(string("DMPLIST.DAT"))
  temp := \fat.openFile(string("DMPLIST.DAT"), "W")

  ' Do writing stuff here....

else

  ' Do reading stuff here...

Kye's fat driver - how to handle errors?

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