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package communication
import (
"log"
)
const (
SLIP_END = 0xC0
SLIP_ESC = 0xDB
SLIP_ESC_END = 0xDC
SLIP_ESC_ESC = 0xDD
SLIP_MAX_PAYLOAD = 1500
)
type dataLink struct {
rx chan []byte
}
func newDataLink() dataLink {
dl := dataLink{}
dl.rx = make(chan []byte)
return dl
}
func (dl *dataLink) start(source chan byte) {
go dl.receive(source)
}
func (dl *dataLink) receive(source chan byte) {
for {
frame := unslip(source)
dl.rx <- frame
}
}
func unslip(source chan byte) []byte {
buffer := make([]byte, 0)
for {
octet := <-source
switch octet {
case SLIP_ESC:
escaped := <-source
switch escaped {
case SLIP_ESC_END:
buffer = append(buffer, SLIP_END)
case SLIP_ESC_ESC:
buffer = append(buffer, SLIP_ESC)
default:
log.Printf("SLIP: Invalid 0x%x followed an escape byte", escaped)
}
case SLIP_END:
return buffer
default:
buffer = append(buffer, octet)
}
}
}
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