From 3b20367381bcd955e604c40d05f489f2221c036a Mon Sep 17 00:00:00 2001 From: Alexandru Gagniuc Date: Sat, 1 Dec 2012 18:07:10 -0600 Subject: [PATCH] demo: Do not use a separate thread for generating data We already have an event-based mechanism in place. Using a thread just adds unneeded complexity, especially for a driver designed not for performance, but for providing a testbed to frontends. Generate the data in the event handler, not in a separate thread. Signed-off-by: Alexandru Gagniuc --- hardware/demo/demo.c | 128 +++++++++++++++---------------------------- 1 file changed, 44 insertions(+), 84 deletions(-) diff --git a/hardware/demo/demo.c b/hardware/demo/demo.c index cf8cef6f..9c7b2b4f 100644 --- a/hardware/demo/demo.c +++ b/hardware/demo/demo.c @@ -78,10 +78,9 @@ struct dev_context { int pipe_fds[2]; GIOChannel *channels[2]; uint8_t sample_generator; - uint8_t thread_running; uint64_t samples_counter; void *session_dev_id; - GTimer *timer; + int64_t starttime; }; static const int hwcaps[] = { @@ -144,8 +143,6 @@ static uint64_t cur_samplerate = SR_KHZ(200); static uint64_t limit_samples = 0; static uint64_t limit_msec = 0; static int default_pattern = PATTERN_SIGROK; -static GThread *my_thread; -static int thread_running; static int hw_dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data); @@ -308,10 +305,10 @@ static int hw_dev_config_set(const struct sr_dev_inst *sdi, int hwcap, return ret; } -static void samples_generator(uint8_t *buf, uint64_t size, void *data) +static void samples_generator(uint8_t *buf, uint64_t size, + struct dev_context *devc) { static uint64_t p = 0; - struct dev_context *devc = data; uint64_t i; /* TODO: Needed? */ @@ -345,83 +342,49 @@ static void samples_generator(uint8_t *buf, uint64_t size, void *data) } } -/* Thread function */ -static void thread_func(void *data) -{ - struct dev_context *devc = data; - uint8_t buf[BUFSIZE]; - uint64_t nb_to_send = 0; - int bytes_written; - double time_cur, time_last, time_diff; - - time_last = g_timer_elapsed(devc->timer, NULL); - - while (thread_running) { - /* Rate control */ - time_cur = g_timer_elapsed(devc->timer, NULL); - - time_diff = time_cur - time_last; - time_last = time_cur; - - nb_to_send = cur_samplerate * time_diff; - - if (limit_samples) { - nb_to_send = MIN(nb_to_send, - limit_samples - devc->samples_counter); - } - - /* Make sure we don't overflow. */ - nb_to_send = MIN(nb_to_send, BUFSIZE); - - if (nb_to_send) { - samples_generator(buf, nb_to_send, data); - devc->samples_counter += nb_to_send; - - g_io_channel_write_chars(devc->channels[1], (gchar *)&buf, - nb_to_send, (gsize *)&bytes_written, NULL); - } - - /* Check if we're done. */ - if ((limit_msec && time_cur * 1000 > limit_msec) || - (limit_samples && devc->samples_counter >= limit_samples)) - { - close(devc->pipe_fds[1]); - thread_running = 0; - } - - g_usleep(10); - } -} - /* Callback handling data */ static int receive_data(int fd, int revents, void *cb_data) { struct dev_context *devc = cb_data; struct sr_datafeed_packet packet; struct sr_datafeed_logic logic; - static uint64_t samples_received = 0; - unsigned char c[BUFSIZE]; - gsize z; + uint8_t buf[BUFSIZE]; + static uint64_t samples_to_send, expected_samplenum, sending_now; + int64_t time, elapsed; (void)fd; (void)revents; - do { - g_io_channel_read_chars(devc->channels[0], - (gchar *)&c, BUFSIZE, &z, NULL); + /* How many "virtual" samples should we have collected by now? */ + time = g_get_monotonic_time(); + elapsed = time - devc->starttime; + expected_samplenum = elapsed * cur_samplerate / 1000000; + /* Of those, how many do we still have to send? */ + samples_to_send = expected_samplenum - devc->samples_counter; - if (z > 0) { - packet.type = SR_DF_LOGIC; - packet.payload = &logic; - logic.length = z; - logic.unitsize = 1; - logic.data = c; - sr_session_send(devc->session_dev_id, &packet); - samples_received += z; - } - } while (z > 0); + if (limit_samples) { + samples_to_send = MIN(samples_to_send, + limit_samples - devc->samples_counter); + } - if (!thread_running && z <= 0) { + while (samples_to_send > 0) { + sending_now = MIN(samples_to_send, sizeof(buf)); + samples_to_send -= sending_now; + samples_generator(buf, sending_now, devc); + + packet.type = SR_DF_LOGIC; + packet.payload = &logic; + logic.length = sending_now; + logic.unitsize = 1; + logic.data = buf; + sr_session_send(devc->session_dev_id, &packet); + devc->samples_counter += sending_now; + } + + + if (devc->samples_counter >= limit_samples) { + sr_spew("We sent a total of %" PRIu64 " samples.", + devc->samples_counter); /* Make sure we don't receive more packets. */ hw_dev_acquisition_stop(NULL, cb_data); return TRUE; @@ -452,6 +415,13 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi, devc->session_dev_id = cb_data; devc->samples_counter = 0; + /* + * Setting two channels connected by a pipe is a remnant from when the + * demo driver generated data in a thread, and collected and sent the + * data in the main program loop. + * They are kept here because it provides a convenient way of setting + * up a timeout-based polling mechanism. + */ if (pipe(devc->pipe_fds)) { /* TODO: Better error message. */ sr_err("%s: pipe() failed", __func__); @@ -474,16 +444,6 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi, sr_session_source_add_channel(devc->channels[0], G_IO_IN | G_IO_ERR, 40, receive_data, devc); - /* Run the demo thread. */ - devc->timer = g_timer_new(); - thread_running = 1; - my_thread = g_thread_try_new("sigrok demo generator", - (GThreadFunc)thread_func, devc, NULL); - if (!my_thread) { - sr_err("%s: g_thread_try_new failed", __func__); - return SR_ERR; /* TODO */ - } - if (!(packet = g_try_malloc(sizeof(struct sr_datafeed_packet)))) { sr_err("%s: packet malloc failed", __func__); return SR_ERR_MALLOC; @@ -507,6 +467,9 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi, meta.num_probes = NUM_PROBES; sr_session_send(devc->session_dev_id, packet); + /* We use this timestamp to decide how many more samples to send. */ + devc->starttime = g_get_monotonic_time(); + g_free(header); g_free(packet); @@ -524,9 +487,6 @@ static int hw_dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data) sr_dbg("Stopping aquisition."); - /* Stop generate thread. */ - thread_running = 0; - sr_session_source_remove_channel(devc->channels[0]); g_io_channel_shutdown(devc->channels[0], FALSE, NULL);