very clever. how appropriate that it arrives just as we decided to drop the power-of-two zoom restriction in ardour :) seriously, thanks a lot for sharing that.

Here's another one, using inline x86-gas. #include <stdint.h> // One minor difference: will give 1 for x == 0. static __inline__ uint32_t nextPowerOfTwo_asm (uint32_t x) { uint32_t r; __asm__ ( "dec %1 \n\t" "bsrl %1,%%ecx \n\t" "jz end \n\t" "inc %%ecx \n\t" "shll %%cl, %0 \n\t" "end: " : "=r" (r) : "r"(x), "0" (1) : "ecx" ); return r; } I have to admit it's not nearly as elegant as the previous solution but... hey, it's my first inline-gas-hack. :) I'm not even sure if this will run any faster than nextPowerOfTwo() with -O2 turned on... The idea basically is to find the highest set bit with bsr (Bit Scan Reverse), add one to that and return 1 shifted left by the number. The include/asm* headers in kernel-source and/or /usr are a very good place to get inspired on these things, btw. Nice online-places to look are http://www-106.ibm.com/developerworks/linux/library/l-ia.html http://www.delorie.com/djgpp/doc/brennan/brennan_att_inline_djgpp.html cheers, Björn On Wed, Sep 17, 2003 at 02:21:32PM +0200, Maarten de Boer wrote: