Thanks for the very quick reply! I don’t think it’s a 64/32 bit problem. I have 32 bit int’s, 16 bit short’s and 8 bit char’s, as expected by the code. Thanks anyway. I’ll keep investigating.

Steve

Hmm, I don’t know. At one point I had a similar problem to what you’re describing, where the JPG image started out correct but then got messed up. It was due to the assembly language DCT algorithm being used at the time. Switching to the C code DCT function fixed the problem, and I then wrote an assembly version of that C code to make it run faster. Is there any chance this might be a data type problem (eg you’re running on a 64 bit machine when this code perhaps assumes 32 bits) or something like that?

Good luck!

Frank.

I’ve been trying to build and use this jpeg code in a Microsoft Visual C++ project to convert 24 bit RGB images to JPG. I removed the __attribute__ stuff and switched it back to using all the C routines instead of the assembler ones, but I can’t get it to work properly. It seems to produce a JPEG file in which the first few 8×8 blocks of pixels look correct but the rest of the image is corrupted. On quality level 8 the length of the strip of blocks which look right is longer than it is on quality level 1. I don’t suppose you’d have any idea what I might have got wrong?

The only changes I made to the code were:
Remove the __attribute__s.
In “encodeMCU”, called “quantization” instead of “quantization_asm”.
In “DCT”, commented out the part were it just calls “jpegdct” and returns.
In “huffman”, made it call the PUTBITS macro instead of “putbits_asm”.
In “read_rgb24_format”, I changed the “#if 0″s to “#if 1″s and vice versa, this stopping it using “read_rgb_yuv”.

Any help gratefully accepted!

Thanks

Steve Howell

- Dean

Old Rev 1 Xplains didn’t have the necessary bootloader in the 1287. Rev 2 and later ones have it, but the procedure described in AVR1907 to enter the bootloader is incomplete. I have summarized my experience in http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=645225 I use Ubuntu, but checked that the pushbuttons I added works with FLIP under Windows, too.