106 lines
3.3 KiB
C++
106 lines
3.3 KiB
C++
// Copyright 2017 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.
|
|
|
|
#include "components/zucchini/buffer_source.h"
|
|
|
|
#include <algorithm>
|
|
|
|
#include "components/zucchini/algorithm.h"
|
|
|
|
namespace zucchini {
|
|
|
|
BufferSource::BufferSource(ConstBufferView buffer) : ConstBufferView(buffer) {}
|
|
|
|
BufferSource& BufferSource::Skip(size_type n) {
|
|
remove_prefix(std::min(n, Remaining()));
|
|
return *this;
|
|
}
|
|
|
|
bool BufferSource::CheckNextBytes(std::initializer_list<uint8_t> bytes) const {
|
|
if (Remaining() < bytes.size())
|
|
return false;
|
|
return std::mismatch(bytes.begin(), bytes.end(), begin()).first ==
|
|
bytes.end();
|
|
}
|
|
|
|
bool BufferSource::ConsumeBytes(std::initializer_list<uint8_t> bytes) {
|
|
if (!CheckNextBytes(bytes))
|
|
return false;
|
|
remove_prefix(bytes.size());
|
|
return true;
|
|
}
|
|
|
|
bool BufferSource::GetRegion(size_type count, ConstBufferView* buffer) {
|
|
DCHECK_NE(begin(), nullptr);
|
|
if (Remaining() < count)
|
|
return false;
|
|
*buffer = ConstBufferView(begin(), count);
|
|
remove_prefix(count);
|
|
return true;
|
|
}
|
|
|
|
// [0aaaaaaa] => 00000000'00000000'00000000'0aaaaaaa
|
|
// [1aaaaaaa 0bbbbbbb] => 00000000'00000000'00bbbbbb'baaaaaaa
|
|
// [1aaaaaaa 1bbbbbbb 0ccccccc] => 00000000'000ccccc'ccbbbbbb'baaaaaaa
|
|
// [1aaaaaaa 1bbbbbbb 1ccccccc 0ddddddd] => 0000dddd'dddccccc'ccbbbbbb'baaaaaaa
|
|
// [1aaaaaaa 1bbbbbbb 1ccccccc 1ddddddd 0???eeee]
|
|
// => eeeedddd'dddccccc'ccbbbbbb'baaaaaaa
|
|
// Note that "???" is discarded. Meanwhile, 1???eeee is invalid.
|
|
bool BufferSource::GetUleb128(uint32_t* ret) {
|
|
int shift_lim =
|
|
static_cast<int>(std::min<size_type>(kMaxLeb128Size, size())) * 7;
|
|
const_iterator cur = cbegin();
|
|
uint32_t value = 0U;
|
|
for (int shift = 0; shift < shift_lim; shift += 7, ++cur) {
|
|
uint32_t b = *cur;
|
|
// When |shift == 28|, |(b & 0x7F) << shift| discards the "???" bits.
|
|
value |= static_cast<uint32_t>(b & 0x7F) << shift;
|
|
if (!(b & 0x80)) {
|
|
*ret = value;
|
|
seek(cur + 1);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// [0Saaaaaa] => SSSSSSSS'SSSSSSSS'SSSSSSSS'SSaaaaaa
|
|
// [1aaaaaaa 0Sbbbbbb] => SSSSSSSS'SSSSSSSS'SSSbbbbb'baaaaaaa
|
|
// [1aaaaaaa 1bbbbbbb 0Scccccc] => SSSSSSSS'SSSScccc'ccbbbbbb'baaaaaaa
|
|
// [1aaaaaaa 1bbbbbbb 1ccccccc 0Sdddddd] => SSSSSddd'dddccccc'ccbbbbbb'baaaaaaa
|
|
// [1aaaaaaa 1bbbbbbb 1ccccccc 1ddddddd 0???Seee]
|
|
// => Seeedddd'dddccccc'ccbbbbbb'baaaaaaa
|
|
// Note that "???" is discarded. Meanwhile, 1???eeee is invalid.
|
|
bool BufferSource::GetSleb128(int32_t* ret) {
|
|
int shift_lim =
|
|
static_cast<int>(std::min<size_type>(kMaxLeb128Size, size())) * 7;
|
|
const_iterator cur = cbegin();
|
|
int32_t value = 0;
|
|
for (int shift = 0; shift < shift_lim; shift += 7, ++cur) {
|
|
uint32_t b = *cur;
|
|
// When |shift == 28|, |(b & 0x7F) << shift| discards the "???" bits.
|
|
value |= static_cast<int32_t>(static_cast<uint32_t>(b & 0x7F) << shift);
|
|
if (!(b & 0x80)) {
|
|
*ret = (shift == 28) ? value : SignExtend(shift + 6, value);
|
|
seek(cur + 1);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool BufferSource::SkipLeb128() {
|
|
int lim = static_cast<int>(std::min<size_type>(kMaxLeb128Size, size()));
|
|
const_iterator cur = cbegin();
|
|
for (int i = 0; i < lim; ++i, ++cur) {
|
|
if (!(*cur & 0x80)) {
|
|
seek(cur + 1);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
} // namespace zucchini
|