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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/jxl/base/padded_bytes.h"
namespace jxl {
void PaddedBytes::IncreaseCapacityTo(size_t capacity) {
JXL_ASSERT(capacity > capacity_);
size_t new_capacity = std::max(capacity, 3 * capacity_ / 2);
new_capacity = std::max<size_t>(64, new_capacity);
// BitWriter writes up to 7 bytes past the end.
CacheAlignedUniquePtr new_data = AllocateArray(new_capacity + 8);
if (new_data == nullptr) {
// Allocation failed, discard all data to ensure this is noticed.
size_ = capacity_ = 0;
return;
}
if (data_ == nullptr) {
// First allocation: ensure first byte is initialized (won't be copied).
new_data[0] = 0;
} else {
// Subsequent resize: copy existing data to new location.
memcpy(new_data.get(), data_.get(), size_);
// Ensure that the first new byte is initialized, to allow write_bits to
// safely append to the newly-resized PaddedBytes.
new_data[size_] = 0;
}
capacity_ = new_capacity;
std::swap(new_data, data_);
}
void PaddedBytes::assign(const uint8_t* new_begin, const uint8_t* new_end) {
JXL_DASSERT(new_begin <= new_end);
const size_t new_size = static_cast<size_t>(new_end - new_begin);
// memcpy requires non-overlapping ranges, and resizing might invalidate the
// new range. Neither happens if the new range is completely to the left or
// right of the _allocated_ range (irrespective of size_).
const uint8_t* allocated_end = begin() + capacity_;
const bool outside = new_end <= begin() || new_begin >= allocated_end;
if (outside) {
resize(new_size); // grow or shrink
memcpy(data(), new_begin, new_size);
return;
}
// There is overlap. The new size cannot be larger because we own the memory
// and the new range cannot include anything outside the allocated range.
JXL_ASSERT(new_size <= capacity_);
// memmove allows overlap and capacity_ is sufficient.
memmove(data(), new_begin, new_size);
size_ = new_size; // shrink
}
} // namespace jxl
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