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tdlib-fork/td/telegram/files/FileBitmask.cpp
levlam 7ae4b6f220 Fix handling of negative offset.
GitOrigin-RevId: ba5a9bbbb5c7cbad6dbe363b84a499b03fe522ea
2018-12-27 03:59:17 +03:00

105 lines
2.5 KiB
C++

//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/telegram/files/FileBitmask.h"
#include "td/utils/common.h"
#include "td/utils/misc.h"
namespace td {
Bitmask::Bitmask(Decode, Slice data) : data_(zero_one_decode(data)) {
}
Bitmask::Bitmask(Ones, int64 count) : data_(narrow_cast<size_t>((count + 7) / 8), '\0') {
for (int64 i = 0; i < count; i++) {
set(i);
}
}
std::string Bitmask::encode() const {
// remove zeroes in the end to make encoding deterministic
td::Slice data(data_);
while (!data.empty() && data.back() == '\0') {
data.remove_suffix(1);
}
return zero_one_encode(data);
}
int64 Bitmask::get_ready_prefix_size(int64 offset, int64 part_size, int64 file_size) const {
if (offset < 0) {
return 0;
}
auto offset_part = offset / part_size;
auto ones = get_ready_parts(offset_part);
if (ones == 0) {
return 0;
}
auto ready_parts_end = (offset_part + ones) * part_size;
if (file_size != 0 && ready_parts_end > file_size) {
ready_parts_end = file_size;
if (offset > file_size) {
offset = file_size;
}
}
auto res = ready_parts_end - offset;
CHECK(res >= 0);
return res;
}
int64 Bitmask::get_total_size(int64 part_size) const {
int64 res = 0;
for (int64 i = 0; i < size(); i++) {
res += static_cast<int64>(get(i));
}
return res * part_size;
}
bool Bitmask::get(int64 offset_part) const {
if (offset_part < 0) {
return 0;
}
auto index = narrow_cast<size_t>(offset_part / 8);
if (index >= data_.size()) {
return 0;
}
return (static_cast<uint8>(data_[index]) & (1 << static_cast<int>(offset_part % 8))) != 0;
}
int64 Bitmask::get_ready_parts(int64 offset_part) const {
int64 res = 0;
while (get(offset_part + res)) {
res++;
}
return res;
}
std::vector<int32> Bitmask::as_vector() const {
std::vector<int32> res;
auto size = narrow_cast<int32>(data_.size() * 8);
for (int32 i = 0; i < size; i++) {
if (get(i)) {
res.push_back(i);
}
}
return res;
}
void Bitmask::set(int64 offset_part) {
CHECK(offset_part >= 0);
auto need_size = narrow_cast<size_t>(offset_part / 8 + 1);
if (need_size > data_.size()) {
data_.resize(need_size, '\0');
}
data_[need_size - 1] |= (1 << (offset_part % 8));
}
int64 Bitmask::size() const {
return static_cast<int64>(data_.size() * 8);
}
} // namespace td