X-Git-Url: https://git.friedersdorff.com/?a=blobdiff_plain;f=common%2Futil.c;h=ff1926d7d14e0c58cb35249ebd5f03b430b7cfbf;hb=083c75816fbad6bcbbc268eb77e5011d2d16656b;hp=36afdd44706670bf0e4ec79b86d7573703f4b692;hpb=62d1ebb91c7b381ce3d88aad9ee0b03bea9fce26;p=max%2Ftmk_keyboard.git

diff --git a/common/util.c b/common/util.c
index 36afdd44..ff1926d7 100644
--- a/common/util.c
+++ b/common/util.c
@@ -17,19 +17,42 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "util.h"
 
-// bit population
-int bitpop(uint8_t bits)
+// bit population - return number of on-bit
+uint8_t bitpop(uint8_t bits)
 {
-    int c;
+    uint8_t c;
     for (c = 0; bits; c++)
-        bits &= bits -1;
+        bits &= bits - 1;
     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]
+*/
+}
+
+uint8_t bitpop16(uint16_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
+// NOTE: return 0 when bit0 is on or all bits are off
+uint8_t biton(uint8_t bits)
+{
+    uint8_t n = 0;
+    if (bits >> 4) { bits >>= 4; n += 4;}
+    if (bits >> 2) { bits >>= 2; n += 2;}
+    if (bits >> 1) { bits >>= 1; n += 1;}
+    return n;
 }
 
-// most significant on-bit
-int biton(uint8_t bits)
+uint8_t biton16(uint16_t bits)
 {
-    int n = 0;
+    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;}