Hello
Here is the table version of fls. Before version of it is wrong.
-------
static inline int fls_table_fls(unsigned n)
{
switch (n) {
case 0: return 0;
case 1 ... 1: return 1;
case 2 ... 3: return 2;
case 4 ... 7: return 3;
case 8 ... 15: return 4;
case 16 ... 31: return 5;
case 32 ... 63: return 6;
case 64 ... 127: return 7;
case 128 ... 255: return 8;
case 256 ... 511: return 9;
case 512 ... 1023: return 10;
case 1024 ... 2047: return 11;
case 2048 ... 4095: return 12;
case 4096 ... 8191: return 13;
case 8192 ... 16383: return 14;
case 16384 ... 32767: return 15;
case 32768 ... 65535: return 16;
case 65536 ... 131071: return 17;
case 131072 ... 262143: return 18;
case 262144 ... 524287: return 19;
case 524288 ... 1048575: return 20;
case 1048576 ... 2097151: return 21;
case 2097152 ... 4194303: return 22;
case 4194304 ... 8388607: return 23;
case 8388608 ... 16777215: return 24;
case 16777216 ... 33554431: return 25;
case 33554432 ... 67108863: return 26;
case 67108864 ... 134217727: return 27;
case 134217728 ... 268435455: return 28;
case 268435456 ... 536870911: return 29;
case 536870912 ... 1073741823: return 30;
case 1073741824 ... 2147483647: return 31;
default:return 32;
}
}
--here is the test log-----
model name : Intel(R) Pentium(R) 4 Mobile CPU 1.60GHz
Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.4/specs
gcc version 2.95.4 20011002 (Debian prerelease)
==== -march=i686 -O3 ====
4294967295 iterations of nil... checksum = 4294967295
real 0m15.548s
user 0m15.500s
sys 0m0.010s
4294967295 iterations of old... checksum = 4294967265
real 0m34.778s
user 0m34.690s
sys 0m0.020s
4294967295 iterations of new... checksum = 4294967265
real 0m56.330s
user 0m56.190s
sys 0m0.000s
4294967295 iterations of new2... checksum = 4294967265
real 0m40.755s
user 0m40.680s
sys 0m0.000s
4294967295 iterations of table... checksum = 4294967265
real 0m49.928s
user 0m49.770s
sys 0m0.050s
------------------
==== -march=i686 -O2 ====
4294967295 iterations of nil... checksum = 4294967295
real 0m28.350s
user 0m28.280s
sys 0m0.020s
4294967295 iterations of old... checksum = 4294967265
real 0m48.199s
user 0m48.100s
sys 0m0.000s
4294967295 iterations of new... checksum = 4294967265
real 0m50.986s
user 0m50.890s
sys 0m0.000s
4294967295 iterations of new2... checksum = 4294967265
real 1m5.356s
user 1m5.210s
sys 0m0.010s
4294967295 iterations of table... checksum = 4294967265
real 0m45.238s
user 0m45.150s
sys 0m0.000s
------------------
==== -O2 ====
4294967295 iterations of nil... checksum = 4294967295
real 0m33.503s
user 0m33.410s
sys 0m0.020s
4294967295 iterations of old... checksum = 4294967265
real 0m50.571s
user 0m50.450s
sys 0m0.020s
4294967295 iterations of new... checksum = 4294967265
real 0m53.324s
user 0m53.200s
sys 0m0.010s
4294967295 iterations of new2... checksum = 4294967265
real 0m56.360s
user 0m56.250s
sys 0m0.000s
4294967295 iterations of table... checksum = 4294967265
real 0m46.524s
user 0m46.440s
sys 0m0.000s
------------------
==== -O3 ====
4294967295 iterations of nil... checksum = 4294967295
real 0m5.421s
user 0m5.410s
sys 0m0.000s
4294967295 iterations of old... checksum = 4294967265
real 0m29.744s
user 0m29.670s
sys 0m0.010s
4294967295 iterations of new... checksum = 4294967265
real 0m53.160s
user 0m53.050s
sys 0m0.000s
4294967295 iterations of new2... checksum = 4294967265
real 0m31.464s
user 0m31.400s
sys 0m0.010s
4294967295 iterations of table... checksum = 4294967265
real 0m46.546s
user 0m46.440s
sys 0m0.000s
------------------
-- 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