Martin Slachta
92 lines
2.6 KiB
C++
92 lines
2.6 KiB
C++
#pragma once
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#include <cstddef>
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#include <cstdint>
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#include <optional>
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#include <span>
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#include <vector>
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namespace tw::net::quicr {
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struct VarInt {
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uint64_t value = 0;
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// byte length of the number in the stream. Use to adjust offset.
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size_t bytes = 0;
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VarInt(uint64_t value) {
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if (value <= 63) {
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bytes = 1;
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} else if (value <= 16383) {
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bytes = 2;
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} else if (value <= 1073741823) {
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bytes = 4;
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}
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bytes = 8;
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this->value = value;
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}
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VarInt(uint64_t value, size_t bytes) {
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this->value = value;
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this->bytes = bytes;
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}
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static std::optional<VarInt> decode(std::span<const std::byte> in) {
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if (in.empty()) return std::nullopt;
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return VarInt(*(uint64_t*)in.data(), sizeof(uint64_t));
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// uint8_t b0 = std::to_integer<uint8_t>(in[0]);
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// uint8_t prefix = (b0 >> 6) & 0x03;
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// size_t len = size_t(1) << prefix; // 1, 2, 4, 8
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// if (in.size() < len) return std::nullopt;
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// uint64_t v = (uint64_t)(b0 & 0x3f);
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// for (size_t i = 1; i < len; ++i) {
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// v = (v << 8) | std::to_integer<uint8_t>(in[i]);
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// }
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// return VarInt(v, len);
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}
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size_t encode(std::vector<std::byte>& out) {
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// if (value <= 63) {
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// out.push_back(std::byte(value));
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// return 1;
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// }
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// if (value <= 16383) {
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// out.push_back(std::byte(0x40 | ((value >> 8) & 0x3f)));
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// out.push_back(std::byte(value & 0xff));
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// return 2;
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// }
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// if (value <= 1073741823) {
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// out.push_back(std::byte(0x80 | ((value >> 24) & 0x3f)));
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// out.push_back(std::byte((value >> 16) & 0xff));
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// out.push_back(std::byte((value >> 8) & 0xff));
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// out.push_back(std::byte(value & 0xff));
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// return 4;
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// }
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// 8-byte
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// out.push_back(std::byte(0xc0 | ((value >> 56) & 0x3f)));
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// out.push_back(std::byte((value >> 48) & 0xff));
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// out.push_back(std::byte((value >> 40) & 0xff));
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// out.push_back(std::byte((value >> 32) & 0xff));
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// out.push_back(std::byte((value >> 24) & 0xff));
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// out.push_back(std::byte((value >> 16) & 0xff));
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// out.push_back(std::byte((value >> 8) & 0xff));
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// out.push_back(std::byte(value & 0xff));
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// insert value into span
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for (int i = 0; i < 8; ++i) {
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out.push_back(std::byte((value >> (i * 8)) & 0xFF));
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}
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return 8;
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}
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};
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}
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