mirror of
https://fuchsia.googlesource.com/third_party/pigweed.googlesource.com/pigweed/pigweed
synced 2024-09-21 14:16:26 +00:00
82d3cb35d3
This change adds a pw_varint module containing functions for encoding and decoding variable-length integers. Change-Id: I50bdf6d9d6762bffb93ee638683de53afed9c849
305 lines
9.8 KiB
C++
305 lines
9.8 KiB
C++
// Copyright 2019 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy
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// of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations
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// under the License.
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#include "pw_varint/varint.h"
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#include <cinttypes>
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#include <cstdint>
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#include <cstring>
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#include <limits>
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#include "gtest/gtest.h"
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namespace pw::varint {
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namespace {
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class Varint : public ::testing::Test {
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protected:
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Varint() : buffer_{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'} {}
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uint8_t buffer_[10];
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};
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TEST_F(Varint, EncodeSizeUnsigned32_SmallSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(0), buffer_));
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EXPECT_EQ(0u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(1), buffer_));
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EXPECT_EQ(1u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(2), buffer_));
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EXPECT_EQ(2u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeUnsigned32_LargeSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(63), buffer_));
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EXPECT_EQ(63u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(64), buffer_));
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EXPECT_EQ(64u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(126), buffer_));
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EXPECT_EQ(126u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT32_C(127), buffer_));
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EXPECT_EQ(127u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeUnsigned32_MultiByte) {
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ASSERT_EQ(2u, EncodeVarint(UINT32_C(128), buffer_));
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EXPECT_EQ(std::memcmp("\x80\x01", buffer_, 2), 0);
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ASSERT_EQ(2u, EncodeVarint(UINT32_C(129), buffer_));
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EXPECT_EQ(std::memcmp("\x81\x01", buffer_, 2), 0);
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ASSERT_EQ(5u,
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EncodeVarint(std::numeric_limits<uint32_t>::max() - 1, buffer_));
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EXPECT_EQ(std::memcmp("\xfe\xff\xff\xff\x0f", buffer_, 5), 0);
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ASSERT_EQ(5u, EncodeVarint(std::numeric_limits<uint32_t>::max(), buffer_));
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EXPECT_EQ(std::memcmp("\xff\xff\xff\xff\x0f", buffer_, 5), 0);
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}
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TEST_F(Varint, EncodeSizeSigned32_SmallSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(INT32_C(0), buffer_));
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EXPECT_EQ(0u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT32_C(-1), buffer_));
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EXPECT_EQ(1u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT32_C(1), buffer_));
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EXPECT_EQ(2u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT32_C(-2), buffer_));
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EXPECT_EQ(3u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT32_C(2), buffer_));
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EXPECT_EQ(4u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeSigned32_LargeSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(INT32_C(-63), buffer_));
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EXPECT_EQ(125u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT32_C(63), buffer_));
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EXPECT_EQ(126u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT32_C(-64), buffer_));
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EXPECT_EQ(127u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeSigned32_MultiByte) {
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ASSERT_EQ(2u, EncodeVarint(INT32_C(64), buffer_));
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EXPECT_EQ(std::memcmp("\x80\x01", buffer_, 2), 0);
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ASSERT_EQ(2u, EncodeVarint(INT32_C(-65), buffer_));
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EXPECT_EQ(std::memcmp("\x81\x01", buffer_, 2), 0);
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ASSERT_EQ(2u, EncodeVarint(INT32_C(65), buffer_));
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EXPECT_EQ(std::memcmp("\x82\x01", buffer_, 2), 0);
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ASSERT_EQ(5u, EncodeVarint(std::numeric_limits<int32_t>::min(), buffer_));
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EXPECT_EQ(std::memcmp("\xff\xff\xff\xff\x0f", buffer_, 5), 0);
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ASSERT_EQ(5u, EncodeVarint(std::numeric_limits<int32_t>::max(), buffer_));
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EXPECT_EQ(std::memcmp("\xfe\xff\xff\xff\x0f", buffer_, 5), 0);
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}
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TEST_F(Varint, EncodeSizeUnsigned64_SmallSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(0), buffer_));
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EXPECT_EQ(0u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(1), buffer_));
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EXPECT_EQ(1u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(2), buffer_));
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EXPECT_EQ(2u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeUnsigned64_LargeSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(63), buffer_));
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EXPECT_EQ(63u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(64), buffer_));
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EXPECT_EQ(64u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(126), buffer_));
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EXPECT_EQ(126u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(UINT64_C(127), buffer_));
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EXPECT_EQ(127u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeUnsigned64_MultiByte) {
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ASSERT_EQ(2u, EncodeVarint(UINT64_C(128), buffer_));
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EXPECT_EQ(std::memcmp("\x80\x01", buffer_, 2), 0);
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ASSERT_EQ(2u, EncodeVarint(UINT64_C(129), buffer_));
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EXPECT_EQ(std::memcmp("\x81\x01", buffer_, 2), 0);
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ASSERT_EQ(5u,
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EncodeVarint(std::numeric_limits<uint32_t>::max() - 1, buffer_));
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EXPECT_EQ(std::memcmp("\xfe\xff\xff\xff\x0f", buffer_, 5), 0);
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ASSERT_EQ(5u, EncodeVarint(std::numeric_limits<uint32_t>::max(), buffer_));
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EXPECT_EQ(std::memcmp("\xff\xff\xff\xff\x0f", buffer_, 5), 0);
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ASSERT_EQ(10u,
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EncodeVarint(std::numeric_limits<uint64_t>::max() - 1, buffer_));
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EXPECT_EQ(
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std::memcmp("\xfe\xff\xff\xff\xff\xff\xff\xff\xff\x01", buffer_, 10), 0);
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ASSERT_EQ(10u, EncodeVarint(std::numeric_limits<uint64_t>::max(), buffer_));
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EXPECT_EQ(
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std::memcmp("\xff\xff\xff\xff\xff\xff\xff\xff\xff\x01", buffer_, 10), 0);
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}
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TEST_F(Varint, EncodeSizeSigned64_SmallSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(INT64_C(0), buffer_));
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EXPECT_EQ(0u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT64_C(-1), buffer_));
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EXPECT_EQ(1u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT64_C(1), buffer_));
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EXPECT_EQ(2u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT64_C(-2), buffer_));
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EXPECT_EQ(3u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT64_C(2), buffer_));
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EXPECT_EQ(4u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeSigned64_LargeSingleByte) {
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ASSERT_EQ(1u, EncodeVarint(INT64_C(-63), buffer_));
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EXPECT_EQ(125u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT64_C(63), buffer_));
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EXPECT_EQ(126u, buffer_[0]);
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ASSERT_EQ(1u, EncodeVarint(INT64_C(-64), buffer_));
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EXPECT_EQ(127u, buffer_[0]);
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}
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TEST_F(Varint, EncodeSizeSigned64_MultiByte) {
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ASSERT_EQ(2u, EncodeVarint(INT64_C(64), buffer_));
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EXPECT_EQ(std::memcmp("\x80\x01", buffer_, 2), 0);
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ASSERT_EQ(2u, EncodeVarint(INT64_C(-65), buffer_));
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EXPECT_EQ(std::memcmp("\x81\x01", buffer_, 2), 0);
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ASSERT_EQ(2u, EncodeVarint(INT64_C(65), buffer_));
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EXPECT_EQ(std::memcmp("\x82\x01", buffer_, 2), 0);
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ASSERT_EQ(
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5u,
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EncodeVarint(static_cast<int64_t>(std::numeric_limits<int32_t>::min()),
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buffer_));
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EXPECT_EQ(std::memcmp("\xff\xff\xff\xff\x0f", buffer_, 5), 0);
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ASSERT_EQ(
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5u,
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EncodeVarint(static_cast<int64_t>(std::numeric_limits<int32_t>::max()),
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buffer_));
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EXPECT_EQ(std::memcmp("\xfe\xff\xff\xff\x0f", buffer_, 5), 0);
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ASSERT_EQ(10u, EncodeVarint(std::numeric_limits<int64_t>::min(), buffer_));
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EXPECT_EQ(
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std::memcmp("\xff\xff\xff\xff\xff\xff\xff\xff\xff\x01", buffer_, 10), 0);
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ASSERT_EQ(10u, EncodeVarint(std::numeric_limits<int64_t>::max(), buffer_));
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EXPECT_EQ(
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std::memcmp("\xfe\xff\xff\xff\xff\xff\xff\xff\xff\x01", buffer_, 10), 0);
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}
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TEST_F(Varint, EncodeDecodeSigned32) {
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// Set the increment to 1 to test every number (this is slow)
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static constexpr int kIncrement = 1'000'009;
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int32_t i = std::numeric_limits<int32_t>::min();
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while (true) {
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size_t encoded = EncodeVarint(i, buffer_);
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int64_t result;
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size_t decoded = DecodeVarint(buffer_, &result);
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EXPECT_EQ(encoded, decoded);
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ASSERT_EQ(i, result);
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if (i > std::numeric_limits<int32_t>::max() - kIncrement) {
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break;
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}
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i += kIncrement;
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}
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}
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TEST_F(Varint, EncodeDecodeUnsigned32) {
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// Set the increment to 1 to test every number (this is slow)
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static constexpr int kIncrement = 1'000'009;
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uint32_t i = 0;
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while (true) {
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size_t encoded = EncodeVarint(i, buffer_);
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uint64_t result;
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size_t decoded = DecodeVarint(buffer_, &result);
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EXPECT_EQ(encoded, decoded);
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ASSERT_EQ(i, result);
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if (i > std::numeric_limits<uint32_t>::max() - kIncrement) {
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break;
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}
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i += kIncrement;
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}
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}
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template <size_t kStringSize>
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auto MakeBuffer(const char (&data)[kStringSize]) {
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constexpr size_t kSizeBytes = kStringSize - 1;
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static_assert(kSizeBytes <= 10, "Varint arrays never need be larger than 10");
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std::array<uint8_t, kSizeBytes> array;
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std::memcpy(array.data(), data, kSizeBytes);
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return array;
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}
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TEST(VarintDecode, DecodeSigned64_SingleByte) {
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int64_t value = -1234;
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x00"), &value), 1u);
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EXPECT_EQ(value, 0);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x01"), &value), 1u);
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EXPECT_EQ(value, -1);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x02"), &value), 1u);
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EXPECT_EQ(value, 1);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x03"), &value), 1u);
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EXPECT_EQ(value, -2);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x04"), &value), 1u);
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EXPECT_EQ(value, 2);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x04"), &value), 1u);
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EXPECT_EQ(value, 2);
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}
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TEST(VarintDecode, DecodeSigned64_MultiByte) {
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int64_t value = -1234;
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x80\x01"), &value), 2u);
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EXPECT_EQ(value, 64);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x81\x01"), &value), 2u);
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EXPECT_EQ(value, -65);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\x82\x01"), &value), 2u);
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EXPECT_EQ(value, 65);
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EXPECT_EQ(DecodeVarint(MakeBuffer("\xff\xff\xff\xff\x0f"), &value), 5u);
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EXPECT_EQ(value, std::numeric_limits<int32_t>::min());
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EXPECT_EQ(DecodeVarint(MakeBuffer("\xfe\xff\xff\xff\x0f"), &value), 5u);
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EXPECT_EQ(value, std::numeric_limits<int32_t>::max());
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EXPECT_EQ(DecodeVarint(MakeBuffer("\xff\xff\xff\xff\xff\xff\xff\xff\xff\x01"),
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&value),
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10u);
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EXPECT_EQ(value, std::numeric_limits<int64_t>::min());
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EXPECT_EQ(DecodeVarint(MakeBuffer("\xfe\xff\xff\xff\xff\xff\xff\xff\xff\x01"),
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&value),
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10u);
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EXPECT_EQ(value, std::numeric_limits<int64_t>::max());
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}
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} // namespace
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} // namespace pw::varint
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