#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;
+}
+
+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
+// 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;}
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;
+}
+
+
+
+uint8_t bitrev(uint8_t bits)
+{
+ bits = (bits & 0x0f)<<4 | (bits & 0xf0)>>4;
+ bits = (bits & 0b00110011)<<2 | (bits & 0b11001100)>>2;
+ bits = (bits & 0b01010101)<<1 | (bits & 0b10101010)>>1;
+ return bits;
+}
+
+uint16_t bitrev16(uint16_t bits)
+{
+ bits = bitrev(bits & 0x00ff)<<8 | bitrev((bits & 0xff00)>>8);
+ return bits;
+}
+
+uint32_t bitrev32(uint32_t bits)
+{
+ bits = (uint32_t)bitrev16(bits & 0x0000ffff)<<16 | bitrev16((bits & 0xffff0000)>>16);
+ return bits;
+}