Sigma: Use software trigger to pinpoint exact sample.

diff --git a/hardware/asix-sigma/asix-sigma.c b/hardware/asix-sigma/asix-sigma.c
index fe57d857c7dc7d7ad073c5e17cf54e82bc4663b9..18664829eb4645a80b3ff4c26f7520fb538c6b81 100644 (file)
--- a/hardware/asix-sigma/asix-sigma.c
+++ b/hardware/asix-sigma/asix-sigma.c
@@ -727,6 +727,37 @@ static int hw_set_configuration(int device_index, int capability, void *value)
        return ret;
 }
 
+/* Software trigger to determine exact trigger position. */
+static int get_trigger_offset(uint16_t *samples, uint16_t last_sample,
+                             struct sigma_trigger *t)
+{
+       int i;
+
+       for (i = 0; i < 8; ++i) {
+               if (i > 0)
+                       last_sample = samples[i-1];
+
+               /* Simple triggers. */
+               if ((samples[i] & t->simplemask) != t->simplevalue)
+                       continue;
+
+               /* Rising edge. */
+               if ((last_sample & t->risingmask) != 0 || (samples[i] &
+                   t->risingmask) != t->risingmask)
+                       continue;
+
+               /* Falling edge. */
+               if ((last_sample & t->fallingmask) != t->fallingmask || (samples[i] &
+                   t->fallingmask) != 0)
+                       continue;
+
+               break;
+       }
+
+       /* If we did not match, return original trigger pos. */
+       return i & 0x7;
+}
+
 /*
  * Decode chunk of 1024 bytes, 64 clusters, 7 events per cluster.
  * Each event is 20ns apart, and can contain multiple samples.
@@ -753,7 +784,7 @@ static int decode_chunk_ts(uint8_t *buf, uint16_t *lastts,
        /* Check if trigger is in this chunk. */
        if (triggerpos != -1) {
                if (cur_samplerate <= MHZ(50))
-                       triggerpos -= EVENTS_PER_CLUSTER;
+                       triggerpos -= EVENTS_PER_CLUSTER - 1;
                else
                        triggeroff = 3;
 
@@ -817,13 +848,12 @@ static int decode_chunk_ts(uint8_t *buf, uint16_t *lastts,
                sent = 0;
                if (i == triggerts) {
                        /*
-                        * Trigger is presumptively not accurate to sample.
-                        * However, it always trigger before the actual event,
-                        * so it would be possible to forward to correct position
-                        * here by manually checking for trigger condition.
+                        * Trigger is not always accurate to sample because of
+                        * pipeline delay. However, it always triggers before
+                        * the actual event. We therefore look at the next
+                        * samples to pinpoint the exact position of the trigger.
                         */
-
-                       tosend = (triggerpos % 7) - triggeroff;
+                       tosend = get_trigger_offset(samples, *lastsample, &trigger);
 
                        if (tosend > 0) {
                                packet.type = DF_LOGIC16;