scpi: Query current time just once, use microseconds for timeout

g_get_monotonic_time() returns current time in microseconds, use the same
granularity for storing the read timeout.
There is also no need to check the timeout if data has just been read.

diff --git a/src/scpi.h b/src/scpi.h
index e9e7084ba0876293a572a1a17327de221f4b69bd..1c2c20d7b40008a207f33082e3592987097c9720 100644 (file)
--- a/src/scpi.h
+++ b/src/scpi.h
@@ -94,7 +94,7 @@ struct sr_scpi_dev_inst {
        int (*read_complete)(void *priv);
        int (*close)(struct sr_scpi_dev_inst *scpi);
        void (*free)(void *priv);
-       unsigned int read_timeout_ms;
+       unsigned int read_timeout_us;
        void *priv;
        /* Only used for quirk workarounds, notably the Rigol DS1000 series. */
        uint64_t firmware_version;

diff --git a/src/scpi/scpi.c b/src/scpi/scpi.c
index adb3e75117a21126a22760e0422331fa9e7530f3..f6865c37dc846d809a016b0627cb4fb44630813d 100644 (file)
--- a/src/scpi/scpi.c
+++ b/src/scpi/scpi.c
@@ -190,7 +190,7 @@ SR_PRIV struct sr_scpi_dev_inst *scpi_dev_inst_new(struct drv_context *drvc,
                        scpi = g_malloc(sizeof(*scpi));
                        *scpi = *scpi_dev;
                        scpi->priv = g_malloc0(scpi->priv_size);
-                       scpi->read_timeout_ms = 1000;
+                       scpi->read_timeout_us = 1000 * 1000;
                        params = g_strsplit(resource, "/", 0);
                        if (scpi->dev_inst_new(scpi->priv, drvc, resource,
                                               params, serialcomm) != SR_OK) {
@@ -417,8 +417,7 @@ SR_PRIV int sr_scpi_get_data(struct sr_scpi_dev_inst *scpi,
 {
        int len;
        GString *response;
-       gint64 laststart;
-       unsigned int elapsed_ms;
+       gint64 laststart, now;
        unsigned int offset;
        int space;
 
@@ -451,16 +450,18 @@ SR_PRIV int sr_scpi_get_data(struct sr_scpi_dev_inst *scpi,
                if (len < 0) {
                        sr_err("Incompletely read SCPI response.");
                        return SR_ERR;
-               } else if (len > 0) {
-                       laststart = g_get_monotonic_time();
+               }
+
+               now = g_get_monotonic_time();
+
+               if (len > 0) {
+                       laststart = now;
                        offset += len;
                        g_string_set_size(response, offset);
-               }
-               /* Quit reading after a period of time without receive data. */
-               elapsed_ms = (g_get_monotonic_time() - laststart) / 1000;
-               if (elapsed_ms >= scpi->read_timeout_ms) {
+               } else if ((now - laststart) >= scpi->read_timeout_us) {
+                       /* Quit reading after a period of time without receiving data. */
                        sr_err("Timed out waiting for SCPI response.");
-                       return SR_ERR;
+                       return SR_ERR_TIMEOUT;
                }
        }