Messages in this thread | | | Date | Fri, 11 Jul 2003 23:33:59 +0100 | From | Matthew Wilcox <> | Subject | do_div vs sector_t |
| |
# define do_div(n,base) ({ \ uint32_t __base = (base); \ uint32_t __rem; \ if (likely(((n) >> 32) == 0)) { \
so if we call do_div() on a u32, the compiler emits nasal daemons. and we do this -- in the antcipatory scheduler:
if (aic->seek_samples) { aic->seek_mean = aic->seek_total + 128; do_div(aic->seek_mean, aic->seek_samples); }
seek_mean is a sector_t so sometimes it's 64-bit on a 32-bit platform. so we can't avoid calling do_div().
This almost works (the warning is harmless since gcc optimises away the call)
# define do_div(n,base) ({ \ uint32_t __base = (base); \ uint32_t __rem; \ if ((sizeof(n) < 8) || (likely(((n) >> 32) == 0))) { \ __rem = (uint32_t)(n) % __base; \ (n) = (uint32_t)(n) / __base; \ } else \ __rem = __div64_32(&(n), __base); \ __rem; \ })
Better ideas?
-- "It's not Hollywood. War is real, war is primarily not about defeat or victory, it is about death. I've seen thousands and thousands of dead bodies. Do you think I want to have an academic debate on this subject?" -- Robert Fisk - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |