On Wed, 30 Apr 2003 22:11:29 -0700
Andrew Morton <akpm@digeo.com> wrote:
> nooo.. That has a big cache footprint. At the very least you should use
> a binary search. gcc will do it for you:
>
> switch (n) {
> case 0 ... 1:
> return 1;
> case 2 ... 3:
> return 2;
> case 4 ... 7:
> return 3;
> case 8 ... 15:
> return 4;
>
> etc.
It is here.
--------------------
static inline int fls_table_fls(unsigned n)
{
switch (n) {
case 0 ... 0: return 1;
case 1 ... 1: return 2;
case 2 ... 3: return 3;
case 4 ... 7: return 4;
case 8 ... 15: return 5;
case 16 ... 31: return 6;
case 32 ... 63: return 7;
case 64 ... 127: return 8;
case 128 ... 255: return 9;
case 256 ... 511: return 10;
case 512 ... 1023: return 11;
case 1024 ... 2047: return 12;
case 2048 ... 4095: return 13;
case 4096 ... 8191: return 14;
case 8192 ... 16383: return 15;
case 16384 ... 32767: return 16;
case 32768 ... 65535: return 17;
case 65536 ... 131071: return 18;
case 131072 ... 262143: return 19;
case 262144 ... 524287: return 20;
case 524288 ... 1048575: return 21;
case 1048576 ... 2097151: return 22;
case 2097152 ... 4194303: return 23;
case 4194304 ... 8388607: return 24;
case 8388608 ... 16777215: return 25;
case 16777216 ... 33554431: return 26;
case 33554432 ... 67108863: return 27;
case 67108864 ... 134217727: return 28;
case 134217728 ... 268435455: return 29;
case 268435456 ... 536870911: return 30;
case 536870912 ... 1073741823: return 31;
default:
}
return 32;
}
Now it in test, I will put log and file into
http://soulinfo.com/~hugang/kernel/
-- Hu Gang / Steve Email : huagng@soulinfo.com, steve@soulinfo.com GPG FinePrint: 4099 3F1D AE01 1817 68F7 D499 A6C2 C418 86C8 610E ICQ# : 205800361 Registered Linux User : 204016 - 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/
This archive was generated by hypermail 2b29 : Wed May 07 2003 - 22:00:12 EST