cb22561995-10-11Fredrik Hübinette (Hubbe) /*\ ||| This file a part of uLPC, and is copyright by Fredrik Hubinette ||| uLPC is distributed as GPL (General Public License) ||| See the files COPYING and DISCLAIMER for more information. \*/
5267b71995-08-09Fredrik Hübinette (Hubbe) #include "stuff.h" /* same thing as (int)floor(log((double)x) / log(2.0)) */ /* Except a bit quicker :) (hopefully) */ int my_log2(unsigned INT32 x) { static char bit[256] = { -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, }; register unsigned int tmp; if(tmp=(x>>16)) { if(x=(tmp>>8)) return bit[x]+24; return bit[tmp]+16; } if(tmp=(x>>8)) return bit[tmp]+8; return bit[x]; } /* Return the number of bits in a 32-bit integer */ int count_bits(unsigned INT32 x) { #define B(X) X+0,X+1,X+1,X+2,\ X+1,X+2,X+2,X+3,\ X+1,X+2,X+2,X+3,\ X+2,X+3,X+3,X+4 static char bits[256] = { B(0), B(1), B(1), B(2), B(1), B(2), B(2), B(3), B(1), B(2), B(2), B(3), B(2), B(3), B(3), B(4) }; return (bits[x & 255] + bits[(x>>8) & 255] + bits[(x>>16) & 255] + bits[(x>>24) & 255]); } /* Return true for integers with more than one bit set */ int is_more_than_one_bit(unsigned INT32 x) { return ((x & 0xaaaaaaaa) && (x & 0x55555555)) || ((x & 0xcccccccc) && (x & 0x33333333)) || ((x & 0xf0f0f0f0) && (x & 0x0f0f0f0f)) || ((x & 0xff00ff00) && (x & 0x00ff00ff)) || ((x & 0xff00ff00) && (x & 0x00ff00ff)) || ((x & 0xffff0000) && (x & 0x0000ffff)); }