bitfield.cpp

linux系统下bt的客户端实现。 采用的是c++

#include "Bitfield.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
//using namespace std;

size_t bitfield::nbytes = 0;
size_t bitfield::nbits = 0;

const unsigned char BIT_HEX[] =
	{ 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };


bitfield::bitfield()
{
	b = new unsigned char[nbytes];
	memset(b, 0, nbytes);
	nset = 0;
}

bitfield::bitfield(size_t bits)
{
	nset = 0;
	nbits = bits;
	nbytes = bits / 8 + (bits % 8 ? 1 : 0);

	b = new unsigned char[nbytes];

}

bitfield::~bitfield()
{
	delete b;
}

void bitfield::SetAll()
{
	nset = nbits;
	for (int i = 0; i < nbits / 8; i++)
		b[i] |= 0xff;

	for (int k = 0; k < (nbits % 8); k++)
		b[nbytes - 1] |= BIT_HEX[k];

}

void bitfield::Set(size_t idx)
{
	if (idx >= nbits)
		return;

	if (!(b[idx / 8] & BIT_HEX[idx % 8])) {
		b[idx / 8] |= BIT_HEX[idx % 8];
		nset++;
	}
}

void bitfield::UnSet(size_t idx)
{
	if (idx >= nbits)
		return;

	if (b[idx / 8] & BIT_HEX[idx % 8]) {
		b[idx / 8] &= (~BIT_HEX[idx % 8]);
		nset--;
	}

}

int bitfield::IsSet(size_t idx) const
{
	if (idx >= nbits)
		return -1;

	return (b[idx / 8] & BIT_HEX[idx % 8]) ? 1 : 0;
}

void bitfield::Empty()
{
	nset = 0;
	memset(b, 0, nbytes);
}

void bitfield::Except(const bitfield & bf)
{
	if (bf.IsEmpty())
		return;

	if (bf.IsFull()) {
		Empty();
		return;
	}

	unsigned char ch;
	for (int i = 0; i < nbytes; i++) {
		ch = b[i];
		ch ^= bf.b[i];
		b[i] &= ch;
	}
	ReCalculate();
}

void bitfield::ReCalculate()
{
	nset = 0;
	for (int i = 0; i < nbytes; i++) {
		unsigned char ch = b[i];
		while (ch) {
			nset++;
			ch &= ch - 1;
		}
	}
}

void bitfield::printout()
{
	printf("%d\n", nset);
	for (int i = 0; i < nbytes; i++)
		printf("%x\n", b[i]);
}

void bitfield::And(const bitfield & bf)
{
	for (int i = 0; i < nbytes; i++)
		b[i] &= bf.b[i];

	ReCalculate();
}

void bitfield::Invert()
{
	for (int i = 0; i < nbits / 8; i++)
		b[i] = ~b[i];


	for (int k = 0; k < nbits % 8; k++) {
		int n = (nbytes - 1) * 8 + k;
		if (IsSet(n))
			UnSet(n);
		else
			Set(n);
	}

	ReCalculate();
}

/*
int main()
{
	bitfield bf(51), bt;
	bt.Set(1);
	bt.Set(31);

	bf.SetAll();
	bf.Except(bt);
	bf.printout();

	bf.Invert();

	bf.And(bt);
	bf.printout();
	return 0;
}*/