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Ethernet: Encode preemption enabled flag

pull/32/head
Paul Hollinsky 2020-09-22 19:19:22 -04:00
parent 1f4358af4b
commit 2c55584962
1 changed files with 14 additions and 5 deletions
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19
communication/packet/ethernetpacket.cpp
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@ -56,11 +56,21 @@ std::shared_ptr<EthernetMessage> HardwareEthernetPacket::DecodeToMessage(const s
bool HardwareEthernetPacket::EncodeFromMessage(const EthernetMessage& message, std::vector<uint8_t>& bytestream, const device_eventhandler_t&) {
const size_t unpaddedSize = message.data.size();
size_t paddedSize = unpaddedSize;
uint16_t description = message.description;
if(!message.noPadding && unpaddedSize < 60)
paddedSize = 60; // Pad out short messages
size_t sizeWithHeader = paddedSize + 5; // DescriptionID and Premption Flags
size_t sizeWithHeader = paddedSize + 4; // DescriptionID and Padded Count
// Description ID Most Significant bit is used to identify preemption frames
if(description & 0x8000)
return false;
if(message.preemptionEnabled) {
sizeWithHeader++; // Make space for the preemption flags
description |= 0x8000;
}
bytestream.reserve(sizeWithHeader + 8); // Also reserve space for the bytes we'll use later on
bytestream.resize(sizeWithHeader);
@ -71,11 +81,10 @@ bool HardwareEthernetPacket::EncodeFromMessage(const EthernetMessage& message, s
bytestream[index++] = uint8_t(paddedSize >> 8);
// Description ID, big endian
bytestream[index++] = uint8_t(message.description >> 8);
bytestream[index++] = uint8_t(message.description);
bytestream[index++] = uint8_t(description >> 8);
bytestream[index++] = uint8_t(description);
// Yes, we reserved and allocated space for the preemption flags even if we're not putting them there
// And yes, the data is intended to move over one byte
// The header is one byte larger if preemption is enabled, shifting the data
if(message.preemptionEnabled)
bytestream[index++] = message.preemptionFlags;