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// This code is in the public domain -- Ignacio Castaño <castano@gmail.com>
#pragma once
#ifndef NV_CORE_BITARRAY_H
#define NV_CORE_BITARRAY_H
#include "nvcore.h"
#include "Array.inl"
namespace nv
{
// @@ Uh, this could be much faster.
inline uint countSetBits(uint32 x) {
uint count = 0;
for(; x != 0; x >>= 1) {
count += (x & 1);
}
return count;
}
// @@ This is even more lame. What was I thinking?
inline uint countSetBits(uint32 x, int bits) {
uint count = 0;
for(; x != 0 && bits != 0; x >>= 1, bits--) {
count += (x & 1);
}
return count;
}
// See "Conditionally set or clear bits without branching" at http://graphics.stanford.edu/~seander/bithacks.html
inline uint setBits(uint w, uint m, bool b) {
return (w & ~m) | (-int(b) & m);
}
// Simple bit array.
class BitArray
{
public:
BitArray() {}
BitArray(uint sz) {
resize(sz);
}
uint size() const { return m_size; }
void clear() { resize(0); }
void resize(uint new_size)
{
m_size = new_size;
m_wordArray.resize( (m_size + 31) >> 5 );
}
void resize(uint new_size, bool init)
{
//if (new_size == m_size) return;
uint old_size = m_size;
uint size_mod_32 = old_size & 31;
uint last_word_index = ((old_size + 31) >> 5) - 1;
uint mask = (1 << size_mod_32) - 1;
uint init_dword;
if (init) {
if (size_mod_32) m_wordArray[last_word_index] |= ~mask;
init_dword = ~0;
}
else {
if (size_mod_32) m_wordArray[last_word_index] &= mask;
init_dword = 0;
}
m_size = new_size;
m_wordArray.resize((new_size + 31) >> 5, init_dword);
// Make sure new bits are initialized correctly.
/*for (uint i = old_size; i < new_size; i++) {
nvCheck(bitAt(i) == init);
}*/
}
/// Get bit.
bool bitAt(uint b) const
{
nvDebugCheck( b < m_size );
return (m_wordArray[b >> 5] & (1 << (b & 31))) != 0;
}
// It may be useful to pack mulitple bit arrays together interleaving their bits.
uint bitsAt(uint idx, uint count) const
{
//nvDebugCheck(count == 2 || count == 4 || count == 8 || count == 16 || count == 32);
nvDebugCheck(count == 2); // @@ Hardcoded for two.
uint b = idx * count;
nvDebugCheck(b < m_size);
return (m_wordArray[b >> 5] & (0x3 << (b & 31))) >> (b & 31);
}
// It would be useful to have a function to set two bits simultaneously.
/*void setBitsAt(uint idx, uint count, uint bits) const
{
//nvDebugCheck(count == 2 || count == 4 || count == 8 || count == 16 || count == 32);
nvDebugCheck(count == 2); // @@ Hardcoded for two.
uint b = idx * count;
nvDebugCheck(b < m_size);
return (m_wordArray[b >> 5] & (0x3 << (b & 31))) >> (b & 31);
}*/
// Set a bit.
void setBitAt(uint idx)
{
nvDebugCheck(idx < m_size);
m_wordArray[idx >> 5] |= (1 << (idx & 31));
}
// Clear a bit.
void clearBitAt(uint idx)
{
nvDebugCheck(idx < m_size);
m_wordArray[idx >> 5] &= ~(1 << (idx & 31));
}
// Toggle a bit.
void toggleBitAt(uint idx)
{
nvDebugCheck(idx < m_size);
m_wordArray[idx >> 5] ^= (1 << (idx & 31));
}
// Set a bit to the given value. @@ Rename modifyBitAt?
void setBitAt(uint idx, bool b)
{
nvDebugCheck(idx < m_size);
m_wordArray[idx >> 5] = setBits(m_wordArray[idx >> 5], 1 << (idx & 31), b);
nvDebugCheck(bitAt(idx) == b);
}
void append(bool value)
{
resize(m_size + 1);
setBitAt(m_size - 1, value);
}
// Clear all the bits.
void clearAll()
{
memset(m_wordArray.buffer(), 0, m_wordArray.size() * sizeof(uint));
}
// Set all the bits.
void setAll()
{
memset(m_wordArray.buffer(), 0xFF, m_wordArray.size() * sizeof(uint));
}
// Toggle all the bits.
void toggleAll()
{
const uint wordCount = m_wordArray.count();
for(uint b = 0; b < wordCount; b++) {
m_wordArray[b] ^= 0xFFFFFFFF;
}
}
// Count the number of bits set.
uint countSetBits() const
{
const uint num = m_wordArray.size();
if( num == 0 ) {
return 0;
}
uint count = 0;
for(uint i = 0; i < num - 1; i++) {
count += nv::countSetBits(m_wordArray[i]);
}
count += nv::countSetBits(m_wordArray[num - 1], m_size & 31);
//piDebugCheck(count + countClearBits() == m_size);
return count;
}
// Count the number of bits clear.
uint countClearBits() const {
const uint num = m_wordArray.size();
if( num == 0 ) {
return 0;
}
uint count = 0;
for(uint i = 0; i < num - 1; i++) {
count += nv::countSetBits(~m_wordArray[i]);
}
count += nv::countSetBits(~m_wordArray[num - 1], m_size & 31);
//piDebugCheck(count + countSetBits() == m_size);
return count;
}
friend void swap(BitArray & a, BitArray & b)
{
swap(a.m_size, b.m_size);
swap(a.m_wordArray, b.m_wordArray);
}
void operator &= (const BitArray & other) {
if (other.m_size != m_size) {
resize(other.m_size);
}
const uint wordCount = m_wordArray.count();
for (uint i = 0; i < wordCount; i++) {
m_wordArray[i] &= other.m_wordArray[i];
}
}
void operator |= (const BitArray & other) {
if (other.m_size != m_size) {
resize(other.m_size);
}
const uint wordCount = m_wordArray.count();
for (uint i = 0; i < wordCount; i++) {
m_wordArray[i] |= other.m_wordArray[i];
}
}
private:
// Number of bits stored.
uint m_size;
// Array of bits.
Array<uint> m_wordArray;
};
} // nv namespace
#endif // NV_CORE_BITARRAY_H
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