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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file contains the implementation of IdAllocator.
#include "../client/id_allocator.h"
#include "../common/logging.h"
namespace gpu {
IdAllocator::IdAllocator() : bitmap_(1) { bitmap_[0] = 0; }
static const unsigned int kBitsPerUint32 = sizeof(Uint32) * 8; // NOLINT
// Looks for the first non-full entry, and return the first free bit in that
// entry. If all the entries are full, it will return the first bit of an entry
// that would be appended, but doesn't actually append that entry to the vector.
unsigned int IdAllocator::FindFirstFree() const {
size_t size = bitmap_.size();
for (unsigned int i = 0; i < size; ++i) {
Uint32 value = bitmap_[i];
if (value != 0xffffffffU) {
for (unsigned int j = 0; j < kBitsPerUint32; ++j) {
if (!(value & (1 << j))) return i * kBitsPerUint32 + j;
}
DLOG(FATAL) << "Code should not reach here.";
}
}
return size*kBitsPerUint32;
}
// Sets the correct bit in the proper entry, resizing the vector if needed.
void IdAllocator::SetBit(unsigned int bit, bool value) {
size_t size = bitmap_.size();
if (bit >= size * kBitsPerUint32) {
size_t newsize = bit / kBitsPerUint32 + 1;
bitmap_.resize(newsize);
for (size_t i = size; i < newsize; ++i) bitmap_[i] = 0;
}
Uint32 mask = 1U << (bit % kBitsPerUint32);
if (value) {
bitmap_[bit / kBitsPerUint32] |= mask;
} else {
bitmap_[bit / kBitsPerUint32] &= ~mask;
}
}
// Gets the bit from the proper entry. This doesn't resize the vector, just
// returns false if the bit is beyond the last entry.
bool IdAllocator::GetBit(unsigned int bit) const {
size_t size = bitmap_.size();
if (bit / kBitsPerUint32 >= size) return false;
Uint32 mask = 1U << (bit % kBitsPerUint32);
return (bitmap_[bit / kBitsPerUint32] & mask) != 0;
}
} // namespace gpu
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