feat: use configured RDS PI code in encoder pipeline

internal/offline/generator.go

@@ -5,6 +5,8 @@ import (
 	"encoding/binary"
 	"fmt"
 	"path/filepath"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/jan/fm-rds-tx/internal/audio"
@@ -44,6 +46,20 @@ func (g *Generator) sourceFor(sampleRate float64) (frameSource, SourceInfo) {
 	return audio.NewConfiguredToneSource(sampleRate, g.cfg.Audio.ToneLeftHz, g.cfg.Audio.ToneRightHz, g.cfg.Audio.ToneAmplitude), SourceInfo{Kind: "tones", SampleRate: sampleRate, Detail: "generated"}
 }
 
+func parsePI(pi string) uint16 {
+	trimmed := strings.TrimSpace(pi)
+	if trimmed == "" {
+		return 0x1234
+	}
+	trimmed = strings.TrimPrefix(trimmed, "0x")
+	trimmed = strings.TrimPrefix(trimmed, "0X")
+	v, err := strconv.ParseUint(trimmed, 16, 16)
+	if err != nil {
+		return 0x1234
+	}
+	return uint16(v)
+}
+
 func (g *Generator) GenerateFrame(duration time.Duration) *output.CompositeFrame {
 	sampleRate := float64(g.cfg.FM.CompositeRateHz)
 	if sampleRate <= 0 {
@@ -80,7 +96,7 @@ func (g *Generator) GenerateFrame(duration time.Duration) *output.CompositeFrame
 
 	// RDS encoder (standards-grade group framing + CRC + diff encoding)
 	rdsEnc, _ := rds.NewEncoder(rds.RDSConfig{
-		PI:         0x1234,
+		PI:         parsePI(g.cfg.RDS.PI),
 		PS:         g.cfg.RDS.PS,
 		RT:         g.cfg.RDS.RadioText,
 		PTY:        uint8(g.cfg.RDS.PTY),

internal/offline/generator_test.go

@@ -126,3 +126,31 @@ func TestLimiterPreventsClipping(t *testing.T) {
 		}
 	}
 }
+
+func TestParsePI(t *testing.T) {
+	tests := []struct {
+		name string
+		in   string
+		want uint16
+	}{
+		{name: "plain hex", in: "1234", want: 0x1234},
+		{name: "0x prefix", in: "0xBEEF", want: 0xBEEF},
+		{name: "uppercase prefix", in: "0XCAFE", want: 0xCAFE},
+		{name: "whitespace", in: " 0x2345 ", want: 0x2345},
+		{name: "empty fallback", in: "", want: 0x1234},
+		{name: "invalid fallback", in: "nope", want: 0x1234},
+	}
+	for _, tt := range tests {
+		if got := parsePI(tt.in); got != tt.want {
+			t.Fatalf("%s: got 0x%04X want 0x%04X", tt.name, got, tt.want)
+		}
+	}
+}
+
+func TestGeneratorUsesConfiguredPI(t *testing.T) {
+	cfg := cfgpkg.Default()
+	cfg.RDS.PI = "BEEF"
+	if got := parsePI(cfg.RDS.PI); got != 0xBEEF {
+		t.Fatalf("configured PI was not parsed as expected: got 0x%04X", got)
+	}
+}

internal/rds/encoder_test.go

@@ -53,6 +53,17 @@ func TestBuildGroup2ABlockCount(t *testing.T) {
 	}
 }
 
+func TestBuildGroupUsesConfiguredPI(t *testing.T) {
+	g0 := buildGroup0A(0xBEEF, 0, false, false, 0, "TESTFM")
+	if g0[0] != 0xBEEF {
+		t.Fatalf("group0A block A not configured PI: %x", g0[0])
+	}
+	g2 := buildGroup2A(0xCAFE, 0, false, false, 0, "Hello World")
+	if g2[0] != 0xCAFE {
+		t.Fatalf("group2A block A not configured PI: %x", g2[0])
+	}
+}
+
 func TestEncoderGenerate(t *testing.T) {
 	cfg := DefaultConfig()
 	cfg.SampleRate = 228000