aboutsummaryrefslogtreecommitdiff
path: root/common/util.c
diff options
context:
space:
mode:
Diffstat (limited to 'common/util.c')
-rw-r--r--common/util.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/common/util.c b/common/util.c
index 36afdd447..644301fe8 100644
--- a/common/util.c
+++ b/common/util.c
@@ -17,19 +17,23 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
17 17
18#include "util.h" 18#include "util.h"
19 19
20// bit population 20// bit population - return number of on-bit
21int bitpop(uint8_t bits) 21uint8_t bitpop(uint8_t bits)
22{ 22{
23 int c; 23 uint8_t c;
24 for (c = 0; bits; c++) 24 for (c = 0; bits; c++)
25 bits &= bits -1; 25 bits &= bits -1;
26 return c; 26 return c;
27/*
28 const uint8_t bit_count[] = { 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4 };
29 return bit_count[bits>>4] + bit_count[bits&0x0F]
30*/
27} 31}
28 32
29// most significant on-bit 33// most significant on-bit - return highest location of on-bit
30int biton(uint8_t bits) 34uint8_t biton(uint8_t bits)
31{ 35{
32 int n = 0; 36 uint8_t n = 0;
33 if (bits >> 4) { bits >>= 4; n += 4;} 37 if (bits >> 4) { bits >>= 4; n += 4;}
34 if (bits >> 2) { bits >>= 2; n += 2;} 38 if (bits >> 2) { bits >>= 2; n += 2;}
35 if (bits >> 1) { bits >>= 1; n += 1;} 39 if (bits >> 1) { bits >>= 1; n += 1;}