From 29da72a76d5e043a181f66e8758c4d511c3ef814 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Fri, 7 Nov 2025 17:09:38 -0500
Subject: cal: refactor

---
 sw/cal/dbc.go | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 sw/cal/dbc.go

(limited to 'sw/cal/dbc.go')

diff --git a/sw/cal/dbc.go b/sw/cal/dbc.go
new file mode 100644
index 0000000..53ca852
--- /dev/null
+++ b/sw/cal/dbc.go
@@ -0,0 +1,81 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"slices"
+
+	"go.einride.tech/can/pkg/dbc"
+)
+
+// Extract signals from the DBC file.
+func parseSignals(filename string, names []string) ([]dbc.SignalDef, error) {
+	// Parse DBC file
+	msgDefs, err := parseDbcFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	// Search for signals
+	sigPtrs := make([]*dbc.SignalDef, len(names))
+	for _, msg := range msgDefs {
+		for i := range names {
+			j := slices.IndexFunc(msg.Signals, func(sig dbc.SignalDef) bool { return sig.Name == dbc.Identifier(names[i]) })
+			if j < 0 {
+				continue
+			}
+			if sigPtrs[i] != nil {
+				return nil, ErrDupSig{msg.Signals[j]}
+			}
+			sigPtrs[i] = &msg.Signals[j]
+		}
+	}
+
+	// Check all signals are present
+	if i := slices.IndexFunc(sigPtrs, func(sp *dbc.SignalDef) bool { return sp == nil }); i >= 0 {
+		return nil, ErrNoSig{filename, names[i]}
+	}
+
+	// Dereference
+	signals := make([]dbc.SignalDef, len(sigPtrs))
+	for i := range sigPtrs {
+		signals[i] = *sigPtrs[i]
+	}
+
+	return signals, nil
+}
+
+func parseDbcFile(filename string) ([]*dbc.MessageDef, error) {
+	// Read file
+	buf, err := os.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	// Parse file
+	parser := dbc.NewParser(filename, buf)
+	if err := parser.Parse(); err != nil {
+		return nil, err
+	}
+
+	// Filter message definitions
+	defs := parser.Defs()
+	msgDefs := make([]*dbc.MessageDef, 0, len(defs))
+	for _, def := range defs {
+		if msg, ok := def.(*dbc.MessageDef); ok {
+			msgDefs = append(msgDefs, msg)
+		}
+	}
+	return msgDefs, nil
+}
+
+func tryAssignSignal(dst **dbc.SignalDef, sig dbc.SignalDef, targetName string) error {
+	if targetName != "" && string(sig.Name) == targetName {
+		if *dst != nil {
+			return fmt.Errorf("%v: duplicate signal '%s'", sig.Pos, sig.Name)
+		}
+		*dst = &sig
+	}
+	return nil
+
+}
-- 
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