From: Gerhard Sittig <redacted>
Date: Sun, 26 Mar 2017 15:56:36 +0000 (+0100)
Subject: serial: determine timeout from most recent set_params() values
X-Git-Url: https://sigrok.org/gitweb/?p=libsigrok.git;a=commitdiff_plain;h=639c6f61c32e508e2d8e2330a7f21cb15e29c294;hp=dca683ef9903f6b932f104fe256a8893759dafaa;ds=sidebyside

serial: determine timeout from most recent set_params() values

Store the most recent successfully applied set of parameters for serial
communication. Re-use these values as a fallback to calculate timeouts,
when the underlying transport fails to provide the current settings.
---

diff --git a/src/libsigrok-internal.h b/src/libsigrok-internal.h
index 053ee4df..812cf3ce 100644
--- a/src/libsigrok-internal.h
+++ b/src/libsigrok-internal.h
@@ -726,6 +726,12 @@ struct sr_serial_dev_inst {
 	char *port;
 	/** Comm params for serial_set_paramstr(). */
 	char *serialcomm;
+	struct {
+		int bit_rate;
+		int data_bits;
+		int parity_bits;
+		int stop_bits;
+	} comm_params;
 	/** libserialport port handle */
 	struct sp_port *sp_data;
 };
diff --git a/src/serial.c b/src/serial.c
index 37b61875..86009e9b 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -468,6 +468,15 @@ SR_PRIV int serial_set_params(struct sr_serial_dev_inst *serial, int baudrate,
 		return SR_ERR;
 	}
 
+	serial->comm_params.bit_rate = baudrate;
+	serial->comm_params.data_bits = bits;
+	serial->comm_params.parity_bits = parity ? 1 : 0;
+	serial->comm_params.stop_bits = stopbits;
+	sr_dbg("DBG: %s() rate %d, %d%s%d", __func__,
+			baudrate, bits,
+			(parity == 0) ? "n" : "x",
+			stopbits);
+
 	return SR_OK;
 }
 
@@ -980,6 +989,7 @@ SR_PRIV int serial_timeout(struct sr_serial_dev_inst *port, int num_bytes)
 	if (sp_new_config(&config) < 0)
 		return timeout_ms;
 
+	/* Get the bitrate and frame length. */
 	bits = baud = 0;
 	do {
 		if (sp_get_config(port->sp_data, config) < 0)
@@ -997,7 +1007,14 @@ SR_PRIV int serial_timeout(struct sr_serial_dev_inst *port, int num_bytes)
 			break;
 		baud = tmp;
 	} while (FALSE);
+	if (!bits || !baud) {
+		baud = port->comm_params.bit_rate;
+		bits = 1 + port->comm_params.data_bits +
+			port->comm_params.parity_bits +
+			port->comm_params.stop_bits;
+	}
 
+	/* Derive the timeout. */
 	if (bits && baud) {
 		/* Throw in 10ms for misc OS overhead. */
 		timeout_ms = 10;