Introduce a new compositor architecture

Having spent the last dev cycle looking at how we could specialize the
compositors for various backends, we once again look for the
commonalities in order to reduce the duplication. In part this is
motivated by the idea that spans is a good interface for both the
existent GL backend and pixman, and so they deserve a dedicated
compositor. xcb/xlib target an identical rendering system and so they
should be using the same compositor, and it should be possible to run
that same compositor locally against pixman to generate reference tests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

P.S. This brings massive upheaval (read breakage) I've tried delaying in
order to fix as many things as possible but now this one patch does far,
far, far too much. Apologies in advance for breaking your favourite
backend, but trust me in that the end result will be much better. :)

1 files changed, 33 insertions, 33 deletions

diff --git a/perf/cairo-stats.c b/perf/cairo-stats.c
index e088e198..c422d6cc 100644
--- a/perf/cairo-stats.c
+++ b/perf/cairo-stats.c
@@ -25,16 +25,25 @@
 
 #include "cairo-stats.h"
 
+#include <assert.h>
+
 void
 _cairo_stats_compute (cairo_stats_t *stats,
 		      cairo_time_t  *values,
 		      int	     num_values)
 {
-    int i;
-    cairo_time_t sumtime;
-    double sum, mean, delta, q1, q3, iqr;
-    double outlier_min, outlier_max;
-    int min_valid, num_valid;
+    cairo_time_t sum, mean, delta, q1, q3, iqr;
+    cairo_time_t outlier_min, outlier_max;
+    int i, min_valid, num_valid;
+
+    assert (num_values > 0);
+
+    if (num_values == 1) {
+	stats->min_ticks = stats->median_ticks = values[0];
+	stats->std_dev = 0;
+	stats->iterations = 1;
+	return;
+    }
 
     /* First, identify any outliers, using the definition of "mild
      * outliers" from:
@@ -48,44 +57,35 @@ _cairo_stats_compute (cairo_stats_t *stats,
      */
     qsort (values, num_values, sizeof (cairo_time_t), _cairo_time_cmp);
 
-    q1 = _cairo_time_to_s (values[(1*num_values)/4]);
-    q3 = _cairo_time_to_s (values[(3*num_values)/4]);
+    q1 = values[1*num_values/4];
+    q3 = values[3*num_values/4];
 
+    /* XXX assumes we have native uint64_t */
     iqr = q3 - q1;
+    outlier_min = q1 - 3 * iqr / 2;
+    outlier_max = q3 + 3 * iqr / 2;
 
-    outlier_min = _cairo_time_from_s (q1 - 1.5 * iqr);
-    outlier_max = _cairo_time_from_s (q3 + 1.5 * iqr);
-
-    min_valid = 0;
-    while (min_valid < num_values &&
-	   _cairo_time_to_s (values[min_valid]) < outlier_min)
-    {
-	min_valid++;
-    }
+    for (i = 0; i < num_values && values[i] < outlier_min; i++)
+	;
+    min_valid = i;
 
-    i = min_valid;
-    num_valid = 0;
-    while (i + num_valid < num_values &&
-	   _cairo_time_to_s (values[i+num_valid]) <= outlier_max)
-    {
-	num_valid++;
-    }
+    for (i = 0; i < num_values && values[i] <= outlier_max; i++)
+	;
+    num_valid = i - min_valid;
+    assert(num_valid);
 
     stats->iterations = num_valid;
     stats->min_ticks = values[min_valid];
-
-    sumtime = _cairo_time_from_s (0);
-    for (i = min_valid; i < min_valid + num_valid; i++) {
-	sumtime = _cairo_time_add (sumtime, values[i]);
-	stats->min_ticks = _cairo_time_min (stats->min_ticks, values[i]);
-    }
-
-    mean = _cairo_time_to_s (sumtime) / num_valid;
     stats->median_ticks = values[min_valid + num_valid / 2];
 
-    sum = 0.0;
+    sum = 0;
+    for (i = min_valid; i < min_valid + num_valid; i++)
+	sum = _cairo_time_add (sum, values[i]);
+    mean = sum / num_valid;
+
+    sum = 0;
     for (i = min_valid; i < min_valid + num_valid; i++) {
-	delta = _cairo_time_to_s (values[i]) - mean;
+	delta = values[i] - mean;
 	sum += delta * delta;
     }