OMAP-L137 - Real-Time File System - File Read

Rizuan,

The fastest way is always going to be to read a block of data rather than a word at a time.

"read" can read more than a single byte at a time.

I would experiment declaring different sizes of buffers of unsigned ints, then use read to fill the buffer in chunks.

http://www.opengroup.org/onlinepubs/000095399/functions/read.html shows an example, but you may need to change char buf[20];;
 to Uint16 buf[20] depending on the endian-ness of your file. Alternatively you can use pointers and malloc instead of fixed arrays. Typically powers of 2 will also tend to be slightly quicker in some cases.

If you are reading the file into memory rather than processing it on the fly, then you could define the buffer to be the size of your image and read it in one big chunk.

BR,

Steve

Hi Steve,

Thanks for your fast reply. I've followed exactly what you have instructed me from the link you provided, and my code is as follows:

#include <ti/rtfs/posix/sys/types.h>

#include <ti/rtfs/posix/unistd.h>

.........

Uint16   readbuf[262144];

Int         fptr, ret;

size_t    nbytes;

.........

 fptr      = open(ImagePath, (O_BINARY|O_RDONLY), 0);

 nbytes = sizeof(readbuf);
 ret       = read(fptr, readbuf, nbytes);

and I still got the error “argument of type "Uint16 *" is incompatible with parameter of type "char *"”

Then, I changed the type of variable ret to ssize_t and I received the following error:

            identifier "ssize_t" is undefined.

For your information, I’m using RTFS 1.10.01.31. Is there any way to change the buffer type to 16 bits from 8 bits ?

Thanks for your kind help.

Best regards,

Rizuan

Thanks Steve. It works! Here, I reattached again the code snippet as reference for others. Sorry for asking about the C language. Really appreciate your suggestion.

#include <ti/rtfs/posix/sys/types.h>

#include <ti/rtfs/posix/unistd.h>

.........

Uint16   readbuf[262144];

Int         fptr, ret;

size_t    nbytes;

.........

 fptr      = open(ImagePath, (O_BINARY|O_RDONLY), 0);

 nbytes = sizeof(readbuf);
 ret       = read(fptr, (char*)readbuf, nbytes);

Best regards,

Rizuan

Excellent :)

You are more than welcome my friend.

Are you getting the performance you need now?

BR,

Steve

Yes, Steve. It is the time for me to focus on my algorithm development. Thanks to all TI employee because of this useful forums.

Thanks,

Rizuan