102 lines
2 KiB
Go
102 lines
2 KiB
Go
package skylab
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import (
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"encoding/binary"
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"encoding/json"
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"math"
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)
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/*
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This file provides helpers used for serializing and deserializing skylab packets.
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It contains common code and interfaces.
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*/
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// float32ToBytes is an internal function used to encode a float value to bytes
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func float32ToBytes(b []byte, f float32, bigEndian bool) {
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bits := math.Float32bits(f)
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if bigEndian {
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binary.BigEndian.PutUint32(b, bits)
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} else {
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binary.LittleEndian.PutUint32(b, bits)
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}
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}
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// float32FromBytes is an internal function used to decode float value from bytes
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func float32FromBytes(b []byte, bigEndian bool) (f float32) {
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var bits uint32
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if bigEndian {
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binary.BigEndian.Uint32(b)
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} else {
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binary.LittleEndian.Uint32(b)
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}
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return math.Float32frombits(bits)
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}
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// Packet is any Skylab-generated packet.
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type Packet interface {
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MarshalPacket() ([]byte, error)
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UnmarshalPacket(p []byte) error
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Id() (uint32, error)
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Size() uint
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}
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// Marshaler is a packet that can be marshalled into bytes.
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type Marshaler interface {
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MarshalPacket() ([]byte, error)
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}
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// Unmarshaler is a packet that can be unmarshalled from bytes.
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type Unmarshaler interface {
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UnmarshalPacket(p []byte) error
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}
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// Ider is a packet that can get its ID, based on the index of the packet, if any.
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type Ider interface {
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Id() (uint32, error)
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}
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// Sizer allows for fast allocation.
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type Sizer interface {
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Size() uint
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}
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// CanSend takes a packet and makes CAN framing data.
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func CanSend(p Packet) (id uint32, data []byte, err error) {
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id, err = p.Id()
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if err != nil {
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return
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}
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data, err = p.MarshalPacket()
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return
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}
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// ---- JSON encoding business ----
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type JSONPacket struct {
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Id uint32
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Data json.RawMessage
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}
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func ToJson(p Packet) (*JSONPacket, error) {
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d, err := json.Marshal(p)
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if err != nil {
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return nil, err
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}
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id, err := p.Id()
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if err != nil {
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return nil, err
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}
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jp := &JSONPacket{Id: id, Data: d}
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return jp, nil
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}
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// we need to be able to parse the JSON as well.
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// this is done using the generator since we can use the switch/case thing
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// since it's the fastest
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