capture: add frame type for defining and setting counters

We might want to add a CTRADD type later on, for relative values rather
than absolute. But this should get us started.

Simply define counters upfront, and then set them during the capture
process.

Obviously, we need to come up with a good way to visualize this
information in the UI.

lib/sp-capture-writer.c

@@ -176,6 +176,10 @@ static inline gboolean
 sp_capture_writer_ensure_space_for (SpCaptureWriter *self,
                                     gsize            len)
 {
+  /* Check for max frame size */
+  if (len > G_MAXUSHORT)
+    return FALSE;
+
   if ((self->len - self->pos) < len)
     {
       if (!sp_capture_writer_flush_data (self))
@@ -952,3 +956,124 @@ sp_capture_writer_stat (SpCaptureWriter *self,
 
   *stat = self->stat;
 }
+
+gboolean
+sp_capture_writer_define_counters (SpCaptureWriter        *self,
+                                   gint64                  time,
+                                   gint                    cpu,
+                                   GPid                    pid,
+                                   const SpCaptureCounter *counters,
+                                   guint                   n_counters)
+{
+  SpCaptureFrameCounterDefine *def;
+  gsize len;
+  guint i;
+
+  g_assert (self != NULL);
+  g_assert (counters != NULL);
+  g_assert ((self->pos % SP_CAPTURE_ALIGN) == 0);
+
+  if (n_counters == 0)
+    return TRUE;
+
+  len = sizeof *def + (sizeof *counters * n_counters);
+
+  sp_capture_writer_realign (&len);
+
+  if (!sp_capture_writer_ensure_space_for (self, len))
+    return FALSE;
+
+  g_assert ((self->pos % SP_CAPTURE_ALIGN) == 0);
+
+  def = (SpCaptureFrameCounterDefine *)&self->buf[self->pos];
+  def->frame.len = len;
+  def->frame.cpu = cpu;
+  def->frame.pid = pid;
+  def->frame.time = time;
+  def->frame.type = SP_CAPTURE_FRAME_CTRDEF;
+  def->frame.padding = 0;
+  def->padding = 0;
+  def->n_counters = n_counters;
+
+  for (i = 0; i < n_counters; i++)
+    def->counters[i] = counters[i];
+
+  self->pos += def->frame.len;
+
+  g_assert ((self->pos % SP_CAPTURE_ALIGN) == 0);
+
+  self->stat.frame_count[SP_CAPTURE_FRAME_CTRDEF]++;
+
+  return TRUE;
+}
+
+gboolean
+sp_capture_writer_set_counters (SpCaptureWriter *self,
+                                gint64           time,
+                                gint             cpu,
+                                GPid             pid,
+                                const guint     *counters_ids,
+                                const gint64    *values,
+                                guint            n_counters)
+{
+  SpCaptureFrameCounterSet *set;
+  gsize len;
+  guint n_groups;
+  guint group;
+  guint field;
+  guint i;
+
+  g_assert (self != NULL);
+  g_assert (counters_ids != NULL);
+  g_assert (values != NULL || !n_counters);
+  g_assert ((self->pos % SP_CAPTURE_ALIGN) == 0);
+
+  if (n_counters == 0)
+    return TRUE;
+
+  /* Determine how many value groups we need */
+  n_groups = n_counters / G_N_ELEMENTS (set->values[0].values);
+  if ((n_groups * G_N_ELEMENTS (set->values[0].values)) != n_counters)
+    n_groups++;
+
+  len = sizeof *set + (n_groups * sizeof (SpCaptureCounterValues));
+
+  sp_capture_writer_realign (&len);
+
+  if (!sp_capture_writer_ensure_space_for (self, len))
+    return FALSE;
+
+  g_assert ((self->pos % SP_CAPTURE_ALIGN) == 0);
+
+  set = (SpCaptureFrameCounterSet *)&self->buf[self->pos];
+  set->frame.len = len;
+  set->frame.cpu = cpu;
+  set->frame.pid = pid;
+  set->frame.time = time;
+  set->frame.type = SP_CAPTURE_FRAME_CTRSET;
+  set->frame.padding = 0;
+  set->padding = 0;
+  set->n_values = n_groups;
+
+  for (i = 0, group = 0, field = 0; i < n_counters; i++)
+    {
+      set->values[group].ids[field] = counters_ids[i];
+      set->values[group].values[field] = values[i];
+
+      field++;
+
+      if (field == G_N_ELEMENTS (set->values[0].values))
+        {
+          field = 0;
+          group++;
+        }
+    }
+
+  self->pos += set->frame.len;
+
+  g_assert ((self->pos % SP_CAPTURE_ALIGN) == 0);
+
+  self->stat.frame_count[SP_CAPTURE_FRAME_CTRSET]++;
+
+  return TRUE;
+}