soft-trigger: Add support for pre-triggering.

[libsigrok.git] / src / soft-trigger.c

diff --git a/src/soft-trigger.c b/src/soft-trigger.c
index 386f8cc662ac4481ca4188f555ac09db78c45168..107e6219c58071597debddcc666c760577c622e6 100644 (file)
--- a/src/soft-trigger.c
+++ b/src/soft-trigger.c
@@ -26,7 +26,8 @@
 /* @endcond */
 
 SR_PRIV struct soft_trigger_logic *soft_trigger_logic_new(
-               const struct sr_dev_inst *sdi, struct sr_trigger *trigger)
+               const struct sr_dev_inst *sdi, struct sr_trigger *trigger,
+               int pre_trigger_samples)
 {
        struct soft_trigger_logic *stl;
 
@@ -35,16 +36,83 @@ SR_PRIV struct soft_trigger_logic *soft_trigger_logic_new(
        stl->trigger = trigger;
        stl->unitsize = (g_slist_length(sdi->channels) + 7) / 8;
        stl->prev_sample = g_malloc0(stl->unitsize);
+       stl->pre_trigger_size = stl->unitsize * pre_trigger_samples;
+       stl->pre_trigger_buffer = g_malloc(stl->pre_trigger_size);
+       stl->pre_trigger_head = stl->pre_trigger_buffer;
+
+       if (stl->pre_trigger_size > 0 && stl->pre_trigger_buffer == NULL) {
+               soft_trigger_logic_free(stl);
+               return NULL;
+       }
 
        return stl;
 }
 
 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
 {
+       g_free(stl->pre_trigger_buffer);
        g_free(stl->prev_sample);
        g_free(stl);
 }
 
+static void pre_trigger_append(struct soft_trigger_logic *stl,
+               uint8_t *buf, int len)
+{
+       /* Avoid uselessly copying more than the pre-trigger size. */
+       if (len > stl->pre_trigger_size) {
+               buf += len - stl->pre_trigger_size;
+               len = stl->pre_trigger_size;
+       }
+
+       /* Update the filling level of the pre-trigger circular buffer. */
+       stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
+                                   stl->pre_trigger_size);
+
+       /* Actually copy data to the pre-trigger circular buffer. */
+       while (len > 0) {
+               size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
+                                 - stl->pre_trigger_head, len);
+               memcpy(stl->pre_trigger_head, buf, size);
+               stl->pre_trigger_head += size;
+               if (stl->pre_trigger_head >= stl->pre_trigger_buffer
+                                            + stl->pre_trigger_size)
+                       stl->pre_trigger_head = stl->pre_trigger_buffer;
+               buf += size;
+               len -= size;
+       }
+}
+
+static void pre_trigger_send(struct soft_trigger_logic *stl,
+               int *pre_trigger_samples)
+{
+       struct sr_datafeed_packet packet;
+       struct sr_datafeed_logic logic;
+
+       packet.type = SR_DF_LOGIC;
+       packet.payload = &logic;
+       logic.unitsize = stl->unitsize;
+
+       if (pre_trigger_samples)
+               *pre_trigger_samples = 0;
+
+       /* If pre-trigger buffer not full, rewind head to the first valid sample. */
+       if (stl->pre_trigger_fill < stl->pre_trigger_size)
+               stl->pre_trigger_head = stl->pre_trigger_buffer;
+
+       /* Send logic packets for the pre-trigger circular buffer content. */
+       while (stl->pre_trigger_fill > 0) {
+               size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
+                                 - stl->pre_trigger_head, stl->pre_trigger_fill);
+               logic.length = size;
+               logic.data = stl->pre_trigger_head;
+               sr_session_send(stl->sdi, &packet);
+               stl->pre_trigger_head = stl->pre_trigger_buffer;
+               stl->pre_trigger_fill -= size;
+               if (pre_trigger_samples)
+                       *pre_trigger_samples += size / stl->unitsize;
+       }
+}
+
 static gboolean logic_check_match(struct soft_trigger_logic *stl,
                uint8_t *sample, struct sr_trigger_match *match)
 {
@@ -80,7 +148,7 @@ static gboolean logic_check_match(struct soft_trigger_logic *stl,
 /* Returns the offset (in samples) within buf of where the trigger
  * occurred, or -1 if not triggered. */
 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
-               uint8_t *buf, int len)
+               uint8_t *buf, int len, int *pre_trigger_samples)
 {
        struct sr_datafeed_packet packet;
        struct sr_trigger_stage *stage;
@@ -116,7 +184,11 @@ SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
                                /* Advance to next stage. */
                                stl->cur_stage++;
                        } else {
-                               /* Matched on last stage, fire trigger. */
+                               /* Matched on last stage, send pre-trigger data. */
+                               pre_trigger_append(stl, buf, i);
+                               pre_trigger_send(stl, pre_trigger_samples);
+
+                               /* Fire trigger. */
                                offset = i / stl->unitsize;
 
                                packet.type = SR_DF_TRIGGER;
@@ -142,6 +214,9 @@ SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
                }
        }
 
+       if (offset == -1)
+               pre_trigger_append(stl, buf, len);
+
        return offset;
 }