mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-19 14:51:47 -05:00
81 lines
2.8 KiB
C++
81 lines
2.8 KiB
C++
///////////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2019, 2021 Edouard Griffiths, F4EXB <f4exb06@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 as version 3 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 V3 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/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////////
|
|
#include "math.h"
|
|
#include <bitset>
|
|
|
|
namespace leansdr
|
|
{
|
|
|
|
int hamming_weight(uint8_t x)
|
|
{
|
|
static const int lut[16] = {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4};
|
|
return lut[x & 15] + lut[x >> 4];
|
|
}
|
|
|
|
int hamming_weight(uint16_t x)
|
|
{
|
|
return hamming_weight((uint8_t)x) + hamming_weight((uint8_t)(x >> 8));
|
|
}
|
|
|
|
int hamming_weight(uint32_t x)
|
|
{
|
|
return std::bitset<32>(x).count();
|
|
// x = x - ((x >> 1) & 0x55555555);
|
|
// x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
|
|
// return (((x + (x >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
|
|
// return hamming_weight((uint16_t)x) + hamming_weight((uint16_t)(x >> 16));
|
|
}
|
|
|
|
int hamming_weight(uint64_t x)
|
|
{
|
|
return std::bitset<64>(x).count();
|
|
// x = x - ((x >> 1) & 0x5555555555555555);
|
|
// x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333);
|
|
// return (((x + (x >> 4)) & 0x0F0F0F0F0F0F0F0F) * 0x0101010101010101) >> 56;
|
|
// return hamming_weight((uint32_t)x) + hamming_weight((uint32_t)(x >> 32));
|
|
}
|
|
|
|
unsigned char parity(uint8_t x)
|
|
{
|
|
x ^= x >> 4;
|
|
return (0x6996 >> (x & 15)) & 1; // 16-entry look-up table
|
|
}
|
|
|
|
unsigned char parity(uint16_t x)
|
|
{
|
|
return parity((uint8_t)(x ^ (x >> 8)));
|
|
}
|
|
|
|
unsigned char parity(uint32_t x)
|
|
{
|
|
return parity((uint16_t)(x ^ (x >> 16)));
|
|
}
|
|
|
|
unsigned char parity(uint64_t x)
|
|
{
|
|
return parity((uint32_t)(x ^ (x >> 32)));
|
|
}
|
|
|
|
int log2i(uint64_t x)
|
|
{
|
|
int n = -1;
|
|
for (; x; ++n, x >>= 1);
|
|
return n;
|
|
}
|
|
|
|
} // leansdr
|