On Thu, 2013-06-27 at 18:58 +0200, Simon Wunderlich wrote: > * change divisor to shift to avoid unnecesary integer divisions That didn't really do much ;-) > d->perfect_tx_time = ieee80211_frame_duration(band, 1200, > - rate->bitrate, erp, 1); > + DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1, That's still the integer division, unless the compiler can do something about it? > + DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1, ditto > + mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate, > + (1 << shift) * 5); That looks even weirder? > + /* IEEE 802.11-2012 18.3.2.4: all values above are: > + * * times 4 for 5 MHz > + * * times 2 for 10 MHz > + */ > + dur *= 1 << shift; Isn't that just "dur <<= shift"? I think "DIV_ROUND_UP(x, 1 << shift)" can probably be written more efficiently? Unless the compiler will do something by itself? Something like DIV_ROUND_UP(x, 1<<shift) == (x + (1<<shift) -1) >> shift I think? OK, it looks like if "x" is *unsigned* then the compiler will do this, but with *signed* values it can't actually know because for negative values it's obviously not actually equivalent. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
