1 files changed, 155 insertions, 0 deletions
diff --git a/sw/cal/signal.go b/sw/cal/signal.go
new file mode 100644
index 0000000..6591c50
--- /dev/null
+++ b/sw/cal/signal.go
@@ -0,0 +1,155 @@
+package main
+
+import (
+	"context"
+	bin "encoding/binary"
+	"fmt"
+	"math"
+
+	"go.einride.tech/can"
+	"go.einride.tech/can/pkg/dbc"
+
+	"git.samanthony.xyz/can_gauge_interface/sw/cal/canbus"
+)
+
+const (
+	sigCtrlId   = 0x1272100
+	sigCtrlMask = 0x1FFFF00
+
+	exide = 1 << 31
+)
+
+type SignalDef struct {
+	index       uint8
+	id          uint32
+	isExtended  bool
+	name        string
+	start, size uint8
+	isBigEndian bool
+	isSigned    bool
+}
+
+func NewSignalDef(index uint8, msg *dbc.MessageDef, sig dbc.SignalDef) (SignalDef, error) {
+	if sig.StartBit > math.MaxUint8 {
+		return SignalDef{}, fmt.Errorf("%s: start bit out of range: %d", sig.Name, sig.StartBit)
+	}
+	if sig.Size > math.MaxUint8 {
+		return SignalDef{}, fmt.Errorf("%s: size out of range: %d", sig.Name, sig.Size)
+	}
+
+	return SignalDef{
+		index,
+		uint32(msg.MessageID) & extMask,
+		msg.MessageID.IsExtended(),
+		string(sig.Name),
+		uint8(sig.StartBit),
+		uint8(sig.Size),
+		sig.IsBigEndian,
+		sig.IsSigned,
+	}, nil
+}
+
+// Transmit a signal's encoding in a Signal Control frame so the Interface can store it in its EEPROM.
+func (sig SignalDef) SendEncoding(bus canbus.Bus) error {
+	frame, err := sig.MarshalFrame()
+	if err != nil {
+		return err
+	}
+
+	var retry int
+	for retry = 0; retry < maxRetries; retry++ {
+		// Write to EEPROM
+		ctx, _ := context.WithTimeout(context.Background(), timeout)
+		if err := bus.Send(ctx, frame); err != nil {
+			return err
+		}
+
+		// Read back
+		request := sigCtrlRequest(sig.index)
+		ctx, _ = context.WithTimeout(context.Background(), timeout)
+		if err := bus.Send(ctx, request); err != nil {
+			return err
+		}
+		ctx, _ = context.WithTimeout(context.Background(), timeout)
+		reply, err := bus.Receive(ctx)
+		if err != nil {
+			return err
+		}
+		var rsig SignalDef
+		err = rsig.UnmarshalFrame(reply)
+		if err == errWrongId {
+			fmt.Println("Wrong ID", reply, "; expected", sigCtrlId)
+			continue
+		} else if err != nil {
+			return err
+		}
+
+		// Verify
+		rsig.index = sig.index
+		rsig.name = sig.name
+		fmt.Println("Received signal encoding", rsig)
+		if rsig == sig {
+			fmt.Printf("Signal %d encoding OK\n", sig.index)
+			return nil // success
+		} else {
+			weprintf("Warning: signal %d verification failed; rewriting...\n", sig.index)
+			continue
+		}
+	}
+	// Max retries exceeded
+	return fmt.Errorf("signal %d verification failed", sig.index)
+}
+
+// Construct a Signal Control REMOTE REQUEST frame.
+func sigCtrlRequest(index uint8) can.Frame {
+	return can.Frame{
+		ID:         sigCtrlId | uint32(index&0xF),
+		IsRemote:   true,
+		IsExtended: true,
+	}
+}
+
+func (sig SignalDef) MarshalFrame() (can.Frame, error) {
+	var data [8]byte
+	if _, err := bin.Encode(data[0:4], bin.BigEndian, uint32(sig.id)&extMask); err != nil {
+		return can.Frame{}, err
+	}
+	if sig.isExtended {
+		data[0] |= 0x80 // EXIDE
+	}
+	data[4] = uint8(sig.start)
+	data[5] = uint8(sig.size)
+	if !sig.isBigEndian {
+		data[6] |= 0x80
+	}
+	if sig.isSigned {
+		data[6] |= 0x40
+	}
+	return can.Frame{
+		ID:         sigCtrlId | uint32(sig.index&0xF),
+		Length:     7,
+		Data:       data,
+		IsExtended: true,
+	}, nil
+}
+
+func (sig *SignalDef) UnmarshalFrame(frame can.Frame) error {
+	if !frame.IsExtended || frame.ID&sigCtrlMask != sigCtrlId {
+		return errWrongId
+	}
+	if frame.Length != 7 {
+		return fmt.Errorf("Signal Control frame has wrong DLC: %d", frame.Length)
+	}
+	sig.index = uint8(frame.ID & 0xF)
+	var id uint32
+	if _, err := bin.Decode(frame.Data[0:4], bin.BigEndian, &id); err != nil {
+		return err
+	}
+	sig.id = id & extMask
+	sig.isExtended = id&exide != 0
+	sig.start = frame.Data[4]
+	sig.size = frame.Data[5]
+	sig.isBigEndian = frame.Data[6]&0x80 == 0
+	sig.isSigned = frame.Data[6]&0x40 != 0
+	return nil
+}