Thanks for your reply. It let me take another run at the problem. It turns out to be a good example of the confusion that can result in “endians”. I see now that the SD card runs on the SPI protocol which is big-endian, however, the data that the big_endian SPI is transferring to the card uses the FAT file system which is little_enidian. I just have to remember that a byte is a byte, as you so correctly emphasize.
@Delron: Wow, I thought I had it rough when having to tinker around with networking :). Yeah, it helped me to realize that the endian craziness stops at the byte level, and a byte’s a byte.
Hello guys wassup?
I have a doubt…earlier this guy said that to fix the endianness issue we can use a magical number before every piece of data, n if the we read the magic number n he is 0xFEFF we have a data with the same format else if 0xFFFE we have to swap memory, but i don get the idea very well
So e.g. if i have a pixel (his order is RGBA) on a little endian machine i can use a rmask n make a AND?
Someone can help me to understand better? ^^
Kalid, hi man!
U can explain the thing about put a magic number before every data? I don get it very well =\
If i have a vector of pixels that i pick n my machine is little endian e.g., n the format of pixels is RGBA (bing endian), like this
0 X RR GG BB AA
what is the idea? How i put a magic number before this pixel n mak a test?
Thanks! ^^
Hi Shanx, good question. The “magic number” is a special header everyone agrees to write before the data.
If you’re reading data and the magic number appears backwards (0xFEFF instead of 0xFFFE), you know the data was stored in a different format and therefore you must byte-swap the data.
This is the strategy used in some Unicode documents – include a header field so people can tell when someone else wrote it differently. So, you just need to check whether the header == 0xFFFE (same byte order) or header == 0xFEFF (different byte order).
awesome is the word…plesae try to include the solution to the problem in detailed!
thanks,.
Awesome post! Thank you for writing this! 
Wow, that explained everything so thorougly. Other articles gave the basics, yet none gave you the practice.
Thanks!
Thanks for the note Michael! Yes, I find it helps to cement understanding with a real example of what’s going on.
Excellent article! Very informative with great examples, and just enough light-heartedness thrown in to make it a fun read.
I have read many other articles on endianess and somewhat understood the topic. But this was the first article I came away from feeling like I understand it well enough to explain it to someone else (the ultimate test IMHO as to whether you truly understand a topic).
Thank you for taking the time to write this. I can honestly say this knowledge will help me in my career; which in turn will help my earning potential. So you should feel very good knowing you have made such an impact in someones life via your efforts.
Thanks Mark, your note made my day :). I know what you mean, it took a while for me to really get why endian problem happened, and why only for multi-byte data (single bytes and the order of bits are a common denominator that all computers agree on, otherwise we’d have the “bit ordering problem” too).
Regarding writing, I find it’s no fun for the writer or reader when done in a stuffy style. Thanks again for the comment.
thnks for this explaination I always had problem with big and little endian
many thanks for your great post.
but where should I set the commend of “setenv/export F_UFMTENDIAN=unit”? in the program, in the compile file or ?
many thanks for your great post.
but where should I set the command of “setenv/export F_UFMTENDIAN=unit”? in the program, in the compile file or ?
Great post! It was really helpful.
Thanks a lot!
great job … thanks
this is good man…even i can only understand 1/4 of it…this should be enough…cheers man.
Thanks, very nice explanation …
Excellent explanation! Much Better Explained than other sources I’ve seen. Well done!