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#include "stdafx.h"
#include "GraphicsId.h"
namespace gui {
const Nat full = 0xFFFFFFFF;
const Nat natBits = CHAR_BIT * sizeof(Nat);
IdMgr::IdMgr() : data(null), count(0) {}
IdMgr::~IdMgr() {
delete []data;
}
Nat IdMgr::alloc() {
if (!data) {
// Initial allocation.
count = 4;
data = new Nat[count];
memset(data, 0, sizeof(Nat) * count);
}
for (Nat i = 0; i < count; i++) {
if (data[i] != full)
return allocate(data[i]) + i*natBits + 1;
}
Nat oldCount = count;
grow();
return allocate(data[oldCount]) + oldCount*natBits + 1;
}
void IdMgr::free(Nat id) {
if (id == 0)
return;
id--;
Nat mask = Nat(1) << (id % natBits);
data[id / natBits] &= ~mask;
}
Nat IdMgr::allocate(Nat &in) {
// Note: This could probably be made more efficient, but it is not really worth it. This is not hot code.
for (Nat i = 0; i < natBits; i++) {
Nat mask = Nat(1) << i;
if ((in & mask) == 0) {
in |= mask;
return i;
}
}
// Should not happen, but to keep the compiler happy.
return 0;
}
void IdMgr::grow() {
// This rate should be more than enough.
Nat newCount = count + 4;
Nat *newData = new Nat[newCount];
// This is a bit wasteful, but does not matter, as we're dealing with very small amounts of data.
memset(newData, 0, sizeof(Nat) * newCount);
memcpy(newData, data, sizeof(Nat) * count);
delete[] data;
count = newCount;
data = newData;
}
}
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