Send two B-channel frames when first frame is received

The size of both frames match the receive size.

src/pstn/pstn.c

@@ -723,18 +723,9 @@ static void bchannel_rx_tx(pstn_t *pstn, uint8_t *data, int len)
 		}
 	}
 
-	uint8_t init_data[len * 2];
-	int offset = 0;
-	if (!pstn->b_transmitting) {
-		PDEBUG(DTEL, DEBUG_DEBUG, "First received b-channel data, filling FIFO with double data of %d bytes.\n", len * 2);
-		memset(init_data, 0xff, len);
-		data = init_data;
-		offset = len;
-	}
-
 	/* load from TX jitter buffer and optionally overload with tones an with caller ID */
-	jitter_load(&pstn->tx_dejitter, data + offset, len);
-	isdn_tone_copy(&pstn->isdn_tone, data + offset, len);
+	jitter_load(&pstn->tx_dejitter, data, len);
+	isdn_tone_copy(&pstn->isdn_tone, data, len);
 
 	switch (pstn->callerid_state) {
 	case PSTN_CID_STATE_OFF:
@@ -766,7 +757,7 @@ static void bchannel_rx_tx(pstn_t *pstn, uint8_t *data, int len)
 				g711_encode_alaw_flipped((uint8_t *)spl, rc * 2, &data_cid, &len_cid, NULL);
 			else
 				g711_encode_ulaw_flipped((uint8_t *)spl, rc * 2, &data_cid, &len_cid, NULL);
-			memcpy(data + offset, data_cid, len_cid);
+			memcpy(data, data_cid, len_cid);
 			free(data_cid);
 		}
 		if (rc < len) {
@@ -798,10 +789,18 @@ static void bchannel_rx_tx(pstn_t *pstn, uint8_t *data, int len)
 		break;
 	}
 
+	if (!pstn->b_transmitting) {
+		uint8_t init_data[len];
+		PDEBUG(DTEL, DEBUG_DEBUG, "First received b-channel data, sending two frames, to preload FIFO with %d extra bytes.\n", len);
+		memset(init_data, 0xff, len);
+		/* forward to interface */
+		ph_socket_tx_msg(&pstn->ph_socket, 1, PH_PRIM_DATA_REQ, init_data, len);
+		pstn->b_transmitting = 1;
+	}
+
 	/* forward to interface */
-	ph_socket_tx_msg(&pstn->ph_socket, 1, PH_PRIM_DATA_REQ, data, len + offset);
+	ph_socket_tx_msg(&pstn->ph_socket, 1, PH_PRIM_DATA_REQ, data, len);
 
-	pstn->b_transmitting = 1;
 }
 
 /*