asix-sigma: re-enable software check for exact trigger position

The hardware provided trigger match location is inaccurate. Do check
sample values against the initial trigger condition spec for a short
range of the retrieved sample data, to refine the trigger marker's
position which is sent to the session feed.

Temporarily ignore the optional sample count limit for trigger-using
acquisitions, to reduce the diff size and simplify review. Since the
hardware transparently compresses sample data, we cannot reliably
determine where to start the download and interpretation of sample data,
and the submission to the session feed. Starting early in the sample
memory content, and sticking with the strict sample count limit, could
clip submission before the actual trigger position.

This implementation provides _at least_ the requested amount of data,
and does cover the spot of interest (the trigger position). This, and
the trigger support's having become operational again, is considered an
important improvement. The inaccuracy is considered acceptable for now.
Trigger-less acquisition does enforce the exact sample count limit.

diff --git a/src/hardware/asix-sigma/protocol.c b/src/hardware/asix-sigma/protocol.c
index 8491d7431af8213616506634cba4f0fed159d2c3..2c00d74dd266612e0d4fcf882f7efc4c81af8164 100644 (file)
--- a/src/hardware/asix-sigma/protocol.c
+++ b/src/hardware/asix-sigma/protocol.c
@@ -1255,7 +1255,7 @@ static int addto_submit_buffer(struct dev_context *devc,
 
        buffer = devc->buffer;
        limits = &devc->limit.submit;
-       if (sr_sw_limits_check(limits))
+       if (!devc->use_triggers && sr_sw_limits_check(limits))
                count = 0;
 
        /*
@@ -1272,7 +1272,7 @@ static int addto_submit_buffer(struct dev_context *devc,
                                return ret;
                }
                sr_sw_limits_update_samples_read(limits, 1);
-               if (sr_sw_limits_check(limits))
+               if (!devc->use_triggers && sr_sw_limits_check(limits))
                        break;
        }
 
@@ -1423,6 +1423,7 @@ static int alloc_sample_buffer(struct dev_context *devc,
         * location. The "4 clusters" distance is an arbitrary choice.
         */
        rewind_trig_arm_pos(devc, 4 * EVENTS_PER_CLUSTER);
+       memset(&interp->trig_chk, 0, sizeof(interp->trig_chk));
 
        /* Determine which DRAM lines to fetch from the device. */
        memset(&interp->fetch, 0, sizeof(interp->fetch));
@@ -1585,61 +1586,44 @@ SR_PRIV int sigma_convert_trigger(const struct sr_dev_inst *sdi)
        return SR_OK;
 }
 
-/* Software trigger to determine exact trigger position. */
-static int get_trigger_offset(uint8_t *samples, uint16_t last_sample,
-       struct sigma_trigger *t)
-{
-       const uint8_t *rdptr;
-       size_t i;
-       uint16_t sample;
-
-       rdptr = samples;
-       sample = 0;
-       for (i = 0; i < 8; i++) {
-               if (i > 0)
-                       last_sample = sample;
-               sample = read_u16le_inc(&rdptr);
-
-               /* Simple triggers. */
-               if ((sample & t->simplemask) != t->simplevalue)
-                       continue;
-
-               /* Rising edge. */
-               if (((last_sample & t->risingmask) != 0) ||
-                   ((sample & t->risingmask) != t->risingmask))
-                       continue;
-
-               /* Falling edge. */
-               if ((last_sample & t->fallingmask) != t->fallingmask ||
-                   (sample & t->fallingmask) != 0)
-                       continue;
-
-               break;
-       }
-
-       /* If we did not match, return original trigger pos. */
-       return i & 0x7;
-}
-
 static gboolean sample_matches_trigger(struct dev_context *devc, uint16_t sample)
 {
-       /* TODO
-        * Check whether the combination of this very sample and the
-        * previous state match the configured trigger condition. This
-        * improves the resolution of the trigger marker's position.
-        * The hardware provided position is coarse, and may point to
-        * a position before the actual match.
-        *
-        * See the previous get_trigger_offset() implementation. This
-        * code needs to get re-used here.
+       struct sigma_sample_interp *interp;
+       uint16_t last_sample;
+       struct sigma_trigger *t;
+       gboolean simple_match, rising_match, falling_match;
+       gboolean matched;
+
+       /*
+        * This logic is about improving the precision of the hardware
+        * provided trigger match position. Software checks are only
+        * required for a short range of samples, and only when a user
+        * specified trigger condition was involved during acquisition.
         */
+       if (!devc)
+               return FALSE;
        if (!devc->use_triggers)
                return FALSE;
+       interp = &devc->interp;
+       if (!interp->trig_chk.armed)
+               return FALSE;
 
-       (void)sample;
-       (void)get_trigger_offset;
-
-       return FALSE;
+       /*
+        * Check if the current sample and its most recent transition
+        * match the initially provided trigger condition. The data
+        * must not fail either of the individual checks. Unused
+        * trigger features remain neutral in the summary expression.
+        */
+       last_sample = interp->last.sample;
+       t = &devc->trigger;
+       simple_match = (sample & t->simplemask) == t->simplevalue;
+       rising_match = ((last_sample & t->risingmask) == 0) &&
+                       ((sample & t->risingmask) == t->risingmask);
+       falling_match = ((last_sample & t->fallingmask) == t->fallingmask) &&
+                       ((sample & t->fallingmask) == 0);
+       matched = simple_match && rising_match && falling_match;
+
+       return matched;
 }
 
 static int send_trigger_marker(struct dev_context *devc)
@@ -1657,21 +1641,16 @@ static int send_trigger_marker(struct dev_context *devc)
 }
 
 static int check_and_submit_sample(struct dev_context *devc,
-       uint16_t sample, size_t count, gboolean check_trigger)
+       uint16_t sample, size_t count)
 {
        gboolean triggered;
        int ret;
 
-       /*
-        * Ignore the condition provided by the "inner loop" logic of
-        * sample memory iteration. Instead use device context status
-        * for the period with software trigger match checks.
-        */
-       check_trigger = devc->interp.trig_chk.armed;
-
-       triggered = check_trigger && sample_matches_trigger(devc, sample);
-       if (triggered)
+       triggered = sample_matches_trigger(devc, sample);
+       if (triggered) {
                send_trigger_marker(devc);
+               devc->interp.trig_chk.matched = TRUE;
+       }
 
        ret = addto_submit_buffer(devc, sample, count);
        if (ret != SR_OK)
@@ -1802,7 +1781,7 @@ static void sigma_decode_dram_cluster(struct dev_context *devc,
        if (tsdiff > 0) {
                sample = devc->interp.last.sample;
                count = tsdiff * devc->interp.samples_per_event;
-               (void)check_and_submit_sample(devc, sample, count, FALSE);
+               (void)check_and_submit_sample(devc, sample, count);
        }
        devc->interp.last.ts = ts + EVENTS_PER_CLUSTER;
 
@@ -1818,27 +1797,27 @@ static void sigma_decode_dram_cluster(struct dev_context *devc,
                item16 = sigma_dram_cluster_data(dram_cluster, evt);
                if (devc->interp.samples_per_event == 4) {
                        sample = sigma_deinterlace_data_4x4(item16, 0);
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                        sample = sigma_deinterlace_data_4x4(item16, 1);
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                        sample = sigma_deinterlace_data_4x4(item16, 2);
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                        sample = sigma_deinterlace_data_4x4(item16, 3);
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                } else if (devc->interp.samples_per_event == 2) {
                        sample = sigma_deinterlace_data_2x8(item16, 0);
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                        sample = sigma_deinterlace_data_2x8(item16, 1);
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                } else {
                        sample = item16;
-                       check_and_submit_sample(devc, sample, 1, triggered);
+                       check_and_submit_sample(devc, sample, 1);
                        devc->interp.last.sample = sample;
                }
                sigma_location_increment(&devc->interp.iter);