serial: Add serial_timeout().

This calculates a proper timeout value for blocking writes on the
given serial port, for the given number of bytes. Timeout is based
on a fixed 10ms OS overhead, baud rate, data bits and stop bits.

diff --git a/src/libsigrok-internal.h b/src/libsigrok-internal.h
index ccf75598299c55d11b6a3956f33ae1ff27283b06..bed08e4c0cbb460fc6bd6b3bd7a69c776805fee2 100644 (file)
--- a/src/libsigrok-internal.h
+++ b/src/libsigrok-internal.h
@@ -656,6 +656,7 @@ SR_PRIV int serial_source_add(struct sr_session *session,
 SR_PRIV int serial_source_remove(struct sr_session *session,
                struct sr_serial_dev_inst *serial);
 SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id);
+SR_PRIV int serial_timeout(struct sr_serial_dev_inst *port, int num_bytes);
 #endif
 
 /*--- hardware/common/ezusb.c -----------------------------------------------*/

diff --git a/src/serial.c b/src/serial.c
index 63ffbe2211f332c645289f36a8a7a81af80a0273..37463573256f26c0c750d789ac931566968ecd69 100644 (file)
--- a/src/serial.c
+++ b/src/serial.c
@@ -798,3 +798,43 @@ SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id)
        sp_free_port_list(ports);
        return tty_devs;
 }
+
+SR_PRIV int serial_timeout(struct sr_serial_dev_inst *port, int num_bytes)
+{
+       struct sp_port_config *config;
+       int timeout_ms, bits, baud, tmp;
+
+       /* Default to 1s. */
+       timeout_ms = 1000;
+
+       if (sp_new_config(&config) < 0)
+               return timeout_ms;
+
+       bits = baud = 0;
+       do {
+               if (sp_get_config(port->data, config) < 0)
+                       break;
+
+               /* Start bit. */
+               bits = 1;
+               if (sp_get_config_bits(config, &tmp) < 0)
+                       break;
+               bits += tmp;
+               if (sp_get_config_stopbits(config, &tmp) < 0)
+                       break;
+               bits += tmp;
+               if (sp_get_config_baudrate(config, &tmp) < 0)
+                       break;
+               baud = tmp;
+       } while (FALSE);
+
+       if (bits && baud) {
+               /* Throw in 10ms for misc OS overhead. */
+               timeout_ms = 10;
+               timeout_ms += ((1000.0 / baud) * bits) * num_bytes;
+       }
+
+       sp_free_config(config);
+
+       return timeout_ms;
+}