Need help in EXI Decoder

[Sravana Kumar K]

Hi Rumen,

This information is regarding https://sourceforge.net/p/exip/bugs/8/

I have changed decoder code something like bellow.

Existing prototype :

errorCode decode(EXIPSchema* schemaPtr, FILE *infile,
                 size_t (*inputStream)(void* buf, size_t size, void* stream))
{
  char buf[INPUT_BUFFER_SIZE];
}

Modified prototype :

errorCode decode(EXIPSchema* schemaPtr, const char *infile,
                 size_t (*inputStream)(void* buf, size_t size, void* stream))
{
  char buf[INPUT_BUFFER_SIZE];
}

Existing readFileInputStream :

size_t readFileInputStream(void* buf, size_t readSize, void* stream)
{
  FILE *infile = (FILE*) stream;
  return fread(buf, 1, readSize, infile);
}

Modified readFileInputStream :

size_t readFileInputStream(void* buf, size_t readSize, void* stream)
{
  memcpy (buf, stream, readSize);
  return readSize;
}

For 'decode' call, I am passing char pointer of exi stream which is length of 850 bytes.
Since INPUT_BUFFER_SIZE is 200. It is able to decode only 200 bytes of exi stream, later it was stopping.

If I increase that INPUT_BUFFER_SIZE to 1000. Now I can able to decode that exi stream

In case of more than 1000 bytes of exi stream, again problem comes.

If I use code as it is taking FILE pointer, then there was no issue with this size, we can keep INPUT_BUFFER_SIZE as 200.

But, when pass exi stream as char pointer then problem coming.

I am writing an interface by using decoder examples which takes char pointer as input(exi) and char pointer as output(xml). As like this

errorCode decode(EXIPSchema* schemaPtr, const char *inStream, char *outStream
                 size_t (*inputStream)(void* buf, size_t size, void* stream))

User can call this function outside library by passing schemaPtr, inStream which is exi content, outStream which is decoded version of exi content (xml)

Regards,
SK

[Denis Froschauer]

Your second function readFileInputStream() must return 200, then 200, 200, 200 and then 50 (indicating to EXIP this is the end of data 50 returned < 200 requested) : total = 850

Denis

[Sravana Kumar K]

Hi Denis,

What you said is correct incase of FILE* as input.

But in my case, I am getting first 200 only and then it stops.

Regards,
SK

[Denis Froschauer]

As I understand, you have a buffer in memory, instead of a file.
This is the same process : when EXIP ask you X bytes, you must return X bytes.
If you return less that X bytes, EXIP understand you haven't data anymore and stops.

Try this :

typedef struct {
char *data;
int len;
int current;
} memoryStream_t;

size_t readMemInputStream(void buf, size_t readSize, void stream) {
memoryStream_t ms = (memoryStream_t )stream;
if (!ms->data)
return 0;
int how = ms->len - ms->current;
if (how > readSize)
how = readSize;
//printf ("readMemInputStream %d how=%d\n", readSize, how);
memcpy (buf, ms->data+ms->current, how);
ms->current += how;
return how;
}

decode() {
memoryStream_t ms;

    ms.data = <the big buffer>;
    ms.len  = <size of the big buffer>;
    ms.current      = 0;

    buffer.ioStrm.readWriteToStream = readMemInputStream;
    buffer.ioStrm.stream = &ms;

...

Denis