1
0
Fork 0
qmk_firmware/common/util.c

80 lines
2.0 KiB
C
Raw Normal View History

2011-07-20 15:32:52 +00:00
/*
Copyright 2011 Jun Wako <wakojun@gmail.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
2010-10-27 11:51:45 +00:00
#include "util.h"
// bit population - return number of on-bit
uint8_t bitpop(uint8_t bits)
2010-10-27 11:51:45 +00:00
{
uint8_t c;
2010-10-27 11:51:45 +00:00
for (c = 0; bits; c++)
2012-11-24 07:34:59 +00:00
bits &= bits - 1;
2010-10-27 11:51:45 +00:00
return c;
/*
const uint8_t bit_count[] = { 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4 };
return bit_count[bits>>4] + bit_count[bits&0x0F]
*/
2010-10-27 11:51:45 +00:00
}
2012-11-24 07:34:59 +00:00
uint8_t bitpop16(uint16_t bits)
{
uint8_t c;
for (c = 0; bits; c++)
bits &= bits - 1;
return c;
}
uint8_t bitpop32(uint32_t bits)
{
uint8_t c;
for (c = 0; bits; c++)
bits &= bits - 1;
return c;
}
// most significant on-bit - return highest location of on-bit
2013-02-15 19:05:58 +00:00
// NOTE: return 0 when bit0 is on or all bits are off
uint8_t biton(uint8_t bits)
2010-10-27 11:51:45 +00:00
{
uint8_t n = 0;
2010-10-27 11:51:45 +00:00
if (bits >> 4) { bits >>= 4; n += 4;}
if (bits >> 2) { bits >>= 2; n += 2;}
if (bits >> 1) { bits >>= 1; n += 1;}
return n;
}
2013-02-15 19:05:58 +00:00
uint8_t biton16(uint16_t bits)
{
uint8_t n = 0;
if (bits >> 8) { bits >>= 8; n += 8;}
if (bits >> 4) { bits >>= 4; n += 4;}
if (bits >> 2) { bits >>= 2; n += 2;}
if (bits >> 1) { bits >>= 1; n += 1;}
return n;
}
uint8_t biton32(uint32_t bits)
{
uint8_t n = 0;
if (bits >>16) { bits >>=16; n +=16;}
if (bits >> 8) { bits >>= 8; n += 8;}
if (bits >> 4) { bits >>= 4; n += 4;}
if (bits >> 2) { bits >>= 2; n += 2;}
if (bits >> 1) { bits >>= 1; n += 1;}
return n;
}