Flush IQ buffer on FFT reconfig

cmd/sdrd/main.go

@@ -436,6 +436,10 @@ func runDSP(ctx context.Context, src sdr.Source, cfg config.Config, det *detecto
 			dcEnabled = upd.dcBlock
 			iqEnabled = upd.iqBalance
 			if cfg.FFTSize != prevFFT || cfg.UseGPUFFT != prevUseGPU {
+				if flushable, ok := src.(sdr.Flushable); ok {
+					flushable.Flush()
+				}
+				gotSamples = false
 				if gpuEngine != nil {
 					gpuEngine.Close()
 					gpuEngine = nil

internal/mock/source.go

@@ -61,3 +61,5 @@ func (s *Source) ReadIQ(n int) ([]complex64, error) {
 func (s *Source) Stats() sdr.SourceStats {
 	return sdr.SourceStats{}
 }
+
+func (s *Source) Flush() {}

internal/sdr/source.go

@@ -22,4 +22,8 @@ type StatsProvider interface {
 	Stats() SourceStats
 }
 
+type Flushable interface {
+	Flush()
+}
+
 var ErrNotImplemented = errors.New("sdrplay support not built; build with -tags sdrplay or use --mock")

internal/sdrplay/sdrplay.go

@@ -287,6 +287,16 @@ func (s *Source) Stats() sdr.SourceStats {
 	return sdr.SourceStats{BufferSamples: s.size, Dropped: s.dropped, Resets: s.resets}
 }
 
+func (s *Source) Flush() {
+	s.mu.Lock()
+	s.head = 0
+	s.size = 0
+	s.mu.Unlock()
+	if s.cond != nil {
+		s.cond.Broadcast()
+	}
+}
+
 func min(a, b int) int {
 	if a < b {
 		return a