Hi all, I've sat down a bit ;-) and came up with an Altivec-optimised IDCT implementation in vlc (well, I integrated Motorla's Altivec IDCT).
This is in fact the same code that already exists in vlc for MacOS X, but it uses the Motorola-published assembler code (you can find it on their site). After some hacking around, I got it integrated into vlc, got it to compile, and eventually to run. However, there's something wrong with the IDCT code; the output is essentially garbage. Makes for some interesting visual effects, but that's about it.... So, I need help to figure out what's going wrong here, to check my asm integration (never done that before), and so on. Attached is a diff against vlc-0.2.82. Have a look; my code is in plugins/idct/idctaltivecasm.h, called from plugins/idct/idctaltivec.c. One thing I'm not sure is if all arguments are passed alright to the asm code. I added code to send to pointers back as output; however they don't seem to match what went in... Have a look at PreScale[], SpecialConstants[], and ps and sc. Anyway, the non-Altivec code gives me: vpar stats: 706 loops among 47 sequence(s) vpar stats: cpu usage (user: 957, system: 6) vpar stats: Read 611 frames/fields (I 49/P 186/B 376) vpar stats: Decoded 228 frames/fields (I 49/P 178/B 1) vpar stats: Read 0 malformed frames/fields (I 0/P 0/B 0) whereas the Altivec one gives: vpar stats: 709 loops among 48 sequence(s) vpar stats: cpu usage (user: 991, system: 3) vpar stats: Read 613 frames/fields (I 50/P 187/B 376) vpar stats: Decoded 305 frames/fields (I 50/P 154/B 101) vpar stats: Read 0 malformed frames/fields (I 0/P 0/B 0) Quite a noticeable improvement, no? ;-) Cheers Michel PS When replying, answer to one list only... ------------------------------------------------------------------------- Michel Lanners | " Read Philosophy. Study Art. 23, Rue Paul Henkes | Ask Questions. Make Mistakes. L-1710 Luxembourg | email [EMAIL PROTECTED] | http://www.cpu.lu/~mlan | Learn Always. "
