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package main
import (
"context"
bin "encoding/binary"
"fmt"
"math"
"strings"
"time"
"go.einride.tech/can"
"go.einride.tech/can/pkg/socketcan"
)
const (
tblCtrlId uint32 = 0x1272000
sigCtrlId uint32 = 0x1272100
stdMask = 0x7FF
extMask = 0x1FFFFFFF
timeout = 1 * time.Second
)
// Transmit a signal's encoding in a Signal Control frame so the Interface can store it in its EEPROM.
func sendEncoding(def SignalDef, sig int, tx *socketcan.Transmitter) error {
// Serialize DATA FIELD
var data [8]byte
if err := serializeEncodingData(def, &data); err != nil {
return err
}
fmt.Println(data)
// Construct ID and send frame
frame := can.Frame{
ID: sigCtrlId | uint32(sig&0xF),
Length: 7,
Data: data,
IsExtended: true,
}
ctx, _ := context.WithTimeout(context.Background(), timeout)
return transmit(tx, frame, ctx)
}
// Serialize the DATA FIELD of a Signal Control frame.
func serializeEncodingData(def SignalDef, data *[8]byte) error {
// SigId field
if _, err := bin.Encode(data[0:4], bin.BigEndian, uint32(def.id)&extMask); err != nil {
return err
}
if def.id.IsExtended() {
data[0] |= 0x80 // EXIDE
}
// Start field
if def.start > math.MaxUint8 {
return fmt.Errorf("%s: start bit out of range: %d>%d", def.name, def.start, math.MaxUint8)
}
data[4] = uint8(def.start)
// Size field
if def.size > math.MaxUint8 {
return fmt.Errorf("%s: size out of range: %d>%d", def.name, def.size, math.MaxUint8)
}
data[5] = uint8(def.size)
// Order and sign flag bits
if !def.isBigEndian {
data[6] |= 0x80
}
if def.isSigned {
data[6] |= 0x40
}
fmt.Println(data)
return nil
}
// Transmit a table in Table Control frames so the Interface can store it in its EEPROM.
func sendTable(tx *socketcan.Transmitter, tbl Table, sig int) error {
// Send populated rows
var i int
for i = 0; i < len(tbl.keys); i++ {
err := sendRow(tx, tbl.keys[i], tbl.vals[i], sig, i)
if err != nil {
return err
}
}
// Fill rest of table with last row
for ; i < tabRows; i++ {
err := sendRow(tx, tbl.keys[len(tbl.keys)-1], tbl.vals[len(tbl.keys)-1], sig, i)
if err != nil {
return err
}
}
return nil
}
// Transmit a Table Control frame containing one row of a table.
func sendRow(tx *socketcan.Transmitter, key int32, val uint16, sig int, row int) error {
// Serialize DATA FIELD
var data [8]byte
if _, err := bin.Encode(data[0:4], bin.BigEndian, key); err != nil {
return err
}
if _, err := bin.Encode(data[4:6], bin.BigEndian, val); err != nil {
return err
}
// Construct ID and send frame
frame := can.Frame{
ID: uint32(tblCtrlId) | uint32((sig<<5)&0xE0) | uint32(row&0x1F),
Length: 6,
Data: data,
IsExtended: true,
}
ctx, _ := context.WithTimeout(context.Background(), timeout)
return transmit(tx, frame, ctx)
}
// Transmit a CAN frame to the bus, retrying if the buffer is full.
func transmit(tx *socketcan.Transmitter, frame can.Frame, ctx context.Context) error {
for {
err := tx.TransmitFrame(ctx, frame)
if err == nil {
return nil // success
} else if strings.HasSuffix(err.Error(), "no buffer space available") {
continue // retry
} else {
return err // error, abort
}
}
}
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