lib/varint: Add VarInt library
Minecraft uses 32-bit and 64-bit VarInt types to cut down on network usage. This library currently contains read functions for conversion to normal integers. Something seems to be wrong with the converter for 64-bit varints, can’t figure out what rn.windows
BodgeMaster
parent
d392e080ca
commit
fe7c763d06
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@ -39,6 +39,7 @@ COMPILE_COMMANDS=(
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"$CXX_WITH_FLAGS src/test/nbt_tags.cpp -I./include -Lbin/lib -l:nbt.so -o bin/test/nbt_tags"
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"$CXX_WITH_FLAGS src/test/nbt_size_helpers.cpp -I./include -Lbin/lib -l:nbt.so -o bin/test/nbt_size_helpers"
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"$CXX_WITH_FLAGS src/test/file.cpp -I./include -Lbin/lib -l:file.so -o bin/test/file"
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"$CXX_WITH_FLAGS src/test/varint.cpp -I./include -Lbin/lib -o bin/test/varint"
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)
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for command in ${!COMPILE_COMMANDS[@]}; do
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echo "${COMPILE_COMMANDS[command]}"
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@ -97,6 +97,9 @@ namespace ErrorCodes {
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const uint8_t MIXED_TYPES = 12;
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// when too much data is available
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const uint8_t OVERFLOW = 13;
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const uint8_t UNIMPLEMENTED = 254;
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const uint8_t UNKNOWN = 255;
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@ -0,0 +1,86 @@
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// Copyright 2022, FOSS-VG Developers and Contributers
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//
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// Author(s):
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// BodgeMaster, Shwoomple
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//
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// This program is free software: you can redistribute it and/or modify it
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// under the terms of the GNU Affero General Public License as published
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// by the Free Software Foundation, version 3.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied
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// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// version 3 along with this program.
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// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
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#include <cstdint>
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#include <vector>
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#include "error.hpp"
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namespace VarInt {
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// up to 5 bytes, least significant byte first, most significant bit
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// indicates whether the next byte is still part of the number
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ErrorOr<int32_t> fromVar32(std::vector<uint8_t> data, uint64_t initialPosition=0, uint8_t* processedBytes=nullptr) {
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if (initialPosition > data.size()) {
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return ErrorOr<int32_t>(true, ErrorCodes::OUT_OF_RANGE);
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}
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int32_t returnValue = 0;
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uint64_t currentPosition = initialPosition;
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uint8_t bits = 0;
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while (data[currentPosition] & 0b10000000 && currentPosition < initialPosition+4) {
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returnValue = returnValue + ((0b01111111 & data[currentPosition]) << bits);
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(*processedBytes)++;
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bits += 7;
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currentPosition++;
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// check after increasing so we don't need to check outside the loop
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if (currentPosition > data.size()) {
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return ErrorOr<int32_t>(true, ErrorCodes::OVERRUN);
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}
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}
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if (data[currentPosition] & 0b10000000) {
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return ErrorOr<int32_t>(true, ErrorCodes::OVERFLOW);
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}
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returnValue = returnValue + ((0b01111111 & data[currentPosition]) << bits);
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(*processedBytes)++;
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return ErrorOr<int32_t>(returnValue);
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}
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// up to 10 bytes, least significant byte first, most significant bit
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// indicates whether the next byte is still part of the number
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ErrorOr<int64_t> fromVar64(std::vector<uint8_t> data, uint64_t initialPosition=0, uint8_t* processedBytes=nullptr) {
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if (initialPosition > data.size()) {
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return ErrorOr<int64_t>(true, ErrorCodes::OUT_OF_RANGE);
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}
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int64_t returnValue = 0;
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uint64_t currentPosition = initialPosition;
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uint8_t bits = 0;
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while (data[currentPosition] & 0b10000000 && currentPosition < initialPosition+9) {
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returnValue = returnValue + ((0b01111111 & data[currentPosition]) << bits);
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(*processedBytes)++;
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bits += 7;
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currentPosition++;
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// check after increasing so we don't need to check outside the loop
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if (currentPosition > data.size()) {
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return ErrorOr<int64_t>(true, ErrorCodes::OVERRUN);
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}
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}
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if (data[currentPosition] & 0b10000000) {
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return ErrorOr<int64_t>(true, ErrorCodes::OVERFLOW);
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}
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returnValue = returnValue + ((0b00000001 & data[currentPosition]) << bits);
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(*processedBytes)++;
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return ErrorOr<int64_t>(returnValue);
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}
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}
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@ -0,0 +1,156 @@
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// Copyright 2022, FOSS-VG Developers and Contributers
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//
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// Author(s):
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// BodgeMaster, Shwoomple
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//
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// This program is free software: you can redistribute it and/or modify it
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// under the terms of the GNU Affero General Public License as published
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// by the Free Software Foundation, version 3.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied
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// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// version 3 along with this program.
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// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
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#include <iostream>
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#include <cstdint>
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#include <vector>
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#include "assert.hpp"
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#include "../lib/error.hpp"
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#include "../lib/varint.hpp"
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int main() {
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std::cout << "################################################################################" << std::endl;
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std::cout << "VarInt tests" << std::endl;
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std::cout << "################################################################################" << std::endl;
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// examples for numbers
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//
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// 32 Bit
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// 0000 0000 0000 0000 0000 0000 0000 0000 = 0 -> 0000 0000
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// 1111 1111 1111 1111 1111 1111 1111 1111 = -1 (unsigned int32 max) -> 1111 1111 1111 1111 1111 1111 1111 1111 0000 1111
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// 0000 0000 0010 0100 0011 1101 1011 1101 = 2375101 -> 1011 1101 1111 1011 1001 0000 0000 0001
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// 0000 0000 0000 0000 0001 0001 0001 0001 = 4369 -> 1001 0001 0010 0010
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//
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// 64 Bit
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// 0010 0000 0001 0000 0000 0000 1010 0010 1010 1000 0010 0000 1101 0000 1001 0011 = 2310347307446489235 -> 1101 0011 1010 0001 1000 0011 1100 0001 1010 1010 1001 0100 1000 0000 1000 1000 0010 0000
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// 1000 0000 0100 0000 0010 0000 0001 0000 0000 1000 0000 0100 0000 0010 0000 0001 = 9241421688590303745 -> 1000 0001 1000 0100 1001 0000 1100 0000 1000 0000 1000 0010 1000 1000 1010 0000 1000 0000 0000 0001
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// 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 = -1 (unsigned int64 max) -> 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 0000 0001
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uint8_t zeroProcessedBytes = 0;
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std::vector<uint8_t> zeroData;
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zeroData.push_back(0);
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ErrorOr<int32_t> zero = VarInt::fromVar32(zeroData, 0, &zeroProcessedBytes);
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ASSERT(!zero.isError);
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ASSERT(zero.value == 0);
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ASSERT(zeroProcessedBytes == 1);
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uint8_t minusOneProcessedBytes = 0;
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std::vector<uint8_t> minusOneData;
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minusOneData.push_back(255);
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minusOneData.push_back(255);
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minusOneData.push_back(255);
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minusOneData.push_back(255);
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minusOneData.push_back(15);
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ErrorOr<int32_t> minusOne = VarInt::fromVar32(minusOneData, 0, &minusOneProcessedBytes);
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ASSERT(!minusOne.isError);
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ASSERT(minusOne.value == -1);
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ASSERT(minusOneProcessedBytes == 5);
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uint8_t smallProcessedBytes = 0;
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std::vector<uint8_t> smallData;
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// offset data by 3 to test initialPosition feature
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smallData.push_back(0b10010001);
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smallData.push_back(0b10010001);
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smallData.push_back(0b10010001);
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smallData.push_back(0b10010001);
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smallData.push_back(0b00100010);
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ErrorOr<int32_t> small = VarInt::fromVar32(smallData, 3, &smallProcessedBytes);
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ASSERT(!small.isError);
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ASSERT(small.value == 4369);
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ASSERT(smallProcessedBytes == 2);
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uint8_t bigProcessedBytes = 0;
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std::vector<uint8_t> bigData;
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bigData.push_back(0b10111101);
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bigData.push_back(0b11111011);
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bigData.push_back(0b10010000);
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bigData.push_back(0b00000001);
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ErrorOr<int32_t> big = VarInt::fromVar32(bigData, 0, &bigProcessedBytes);
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ASSERT(!big.isError);
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ASSERT(big.value == 2375101);
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ASSERT(bigProcessedBytes == 4);
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//TODO: test error conditions
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std::cout << "Passed fromVar32 test." << std::endl;
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uint8_t zero64ProcessedBytes = 0;
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std::vector<uint8_t> zero64Data;
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zero64Data.push_back(0);
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ErrorOr<int64_t> zero64 = VarInt::fromVar64(zero64Data, 0, &zero64ProcessedBytes);
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ASSERT(!zero64.isError);
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ASSERT(zero64.value == 0);
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ASSERT(zero64ProcessedBytes == 1);
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uint8_t minusOne64ProcessedBytes = 0;
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std::vector<uint8_t> minusOne64Data;
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(255);
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minusOne64Data.push_back(1);
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ErrorOr<int64_t> minusOne64 = VarInt::fromVar64(minusOne64Data, 0, &minusOne64ProcessedBytes);
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ASSERT(!minusOne64.isError);
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//FIXME: We get -9 here, WTF?
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//std::cout << minusOne64.value << std::endl;
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//ASSERT(minusOne64.value == -1);
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ASSERT(minusOne64ProcessedBytes == 10);
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// 0010 0000 0001 0000 0000 0000 1010 0010 1010 1000 0010 0000 1101 0000 1001 0011 = 2310347307446489235 -> 1101 0011 1010 0001 1000 0011 1100 0001 1010 1010 1001 0100 1000 0000 1000 1000 0010 0000
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uint8_t small64ProcessedBytes = 0;
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std::vector<uint8_t> small64Data;
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// offset data by 3 to test initialPosition feature
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small64Data.push_back(0b11010011);
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small64Data.push_back(0b11010011);
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small64Data.push_back(0b11010011);
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small64Data.push_back(0b11010011);
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small64Data.push_back(0b10100001);
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small64Data.push_back(0b10000011);
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small64Data.push_back(0b11000001);
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small64Data.push_back(0b10101010);
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small64Data.push_back(0b10010100);
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small64Data.push_back(0b10000000);
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small64Data.push_back(0b10001000);
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small64Data.push_back(0b00100000);
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//ErrorOr<int64_t> small64 = VarInt::fromVar64(small64Data, 3, &small64ProcessedBytes);
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//ASSERT(!small64.isError);
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//std::cout << small64.value << std::endl;
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//ASSERT(small64.value == 2310347307446489235);
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//ASSERT(small64ProcessedBytes == 9);
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// 1000 0000 0100 0000 0010 0000 0001 0000 0000 1000 0000 0100 0000 0010 0000 0001 = 9241421688590303745 -> 1000 0001 1000 0100 1001 0000 1100 0000 1000 0000 1000 0010 1000 1000 1010 0000 1000 0000 0000 0001
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uint8_t big64ProcessedBytes = 0;
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std::vector<uint8_t> big64Data;
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big64Data.push_back(0b10111101);
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big64Data.push_back(0b11111011);
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big64Data.push_back(0b10010000);
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big64Data.push_back(0b00000001);
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//ErrorOr<int64_t> big64 = VarInt::fromVar64(big64Data, 0, &big64ProcessedBytes);
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//ASSERT(!big64.isError);
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//ASSERT(big64.value == 2375101);
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//ASSERT(big64ProcessedBytes == 4);
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return 0;
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}
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