[Pixman] [PATCH 09/15] pixman-filter: reduce amount of malloc/free/memcpy to generate filter

[spitzak at gmail.com]

From: Bill Spitzak <spitzak at gmail.com>

Rearranged so that the entire block of memory for the filter pair
is allocated first, and then filled in. Previous version allocated
and freed two temporary buffers for each filter and did an extra
memcpy.

v8: small refactor to remove the filter_width function

v10: Restored filter_width function but with arguments changed to
     match later patches

v11: Removed unused arg and pointer from filter_width function
     Whitespace fixes.

Signed-off-by: Bill Spitzak <spitzak at gmail.com>
Reviewed-by: Oded Gabbay <oded.gabbay at gmail.com>
Acked-by: Søren Sandmann <soren.sandmann at gmail.com>
---
 pixman/pixman-filter.c | 56 +++++++++++++++++++++-----------------------------
 1 file changed, 23 insertions(+), 33 deletions(-)

diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
index aa7bb80..c018a67 100644
--- a/pixman/pixman-filter.c
+++ b/pixman/pixman-filter.c
@@ -217,25 +217,17 @@ integral (pixman_kernel_t kernel1, double x1,
     }
 }
 
-static pixman_fixed_t *
-create_1d_filter (int             *width,
+static void
+create_1d_filter (int              width,
 		  pixman_kernel_t  reconstruct,
 		  pixman_kernel_t  sample,
 		  double           scale,
-		  int              n_phases)
+		  int              n_phases,
+		  pixman_fixed_t *p)
 {
-    pixman_fixed_t *params, *p;
     double step;
-    double size;
     int i;
 
-    size = scale * filters[sample].width + filters[reconstruct].width;
-    *width = ceil (size);
-
-    p = params = malloc (*width * n_phases * sizeof (pixman_fixed_t));
-    if (!params)
-        return NULL;
-
     step = 1.0 / n_phases;
 
     for (i = 0; i < n_phases; ++i)
@@ -250,8 +242,8 @@ create_1d_filter (int             *width,
 	 * and sample positions.
 	 */
 
-	x1 = ceil (frac - *width / 2.0 - 0.5);
-        x2 = x1 + *width;
+	x1 = ceil (frac - width / 2.0 - 0.5);
+	x2 = x1 + width;
 
 	total = 0;
         for (x = x1; x < x2; ++x)
@@ -279,7 +271,7 @@ create_1d_filter (int             *width,
         }
 
 	/* Normalize */
-	p -= *width;
+	p -= width;
         total = 1 / total;
         new_total = 0;
 	for (x = x1; x < x2; ++x)
@@ -291,10 +283,15 @@ create_1d_filter (int             *width,
 	}
 
 	if (new_total != pixman_fixed_1)
-	    *(p - *width / 2) += (pixman_fixed_1 - new_total);
+	    *(p - width / 2) += (pixman_fixed_1 - new_total);
     }
+}
 
-    return params;
+
+static int
+filter_width (pixman_kernel_t reconstruct, pixman_kernel_t sample, double size)
+{
+    return ceil (filters[reconstruct].width + size * filters[sample].width);
 }
 
 #ifdef PIXMAN_GNUPLOT
@@ -426,38 +423,31 @@ pixman_filter_create_separable_convolution (int             *n_values,
 {
     double sx = fabs (pixman_fixed_to_double (scale_x));
     double sy = fabs (pixman_fixed_to_double (scale_y));
-    pixman_fixed_t *horz = NULL, *vert = NULL, *params = NULL;
+    pixman_fixed_t *params;
     int subsample_x, subsample_y;
     int width, height;
 
+    width = filter_width (reconstruct_x, sample_x, sx);
     subsample_x = (1 << subsample_bits_x);
-    subsample_y = (1 << subsample_bits_y);
 
-    horz = create_1d_filter (&width, reconstruct_x, sample_x, sx, subsample_x);
-    vert = create_1d_filter (&height, reconstruct_y, sample_y, sy, subsample_y);
+    height = filter_width (reconstruct_y, sample_y, sy);
+    subsample_y = (1 << subsample_bits_y);
 
-    if (!horz || !vert)
-        goto out;
-    
     *n_values = 4 + width * subsample_x + height * subsample_y;
     
     params = malloc (*n_values * sizeof (pixman_fixed_t));
     if (!params)
-        goto out;
+	return NULL;
 
     params[0] = pixman_int_to_fixed (width);
     params[1] = pixman_int_to_fixed (height);
     params[2] = pixman_int_to_fixed (subsample_bits_x);
     params[3] = pixman_int_to_fixed (subsample_bits_y);
 
-    memcpy (params + 4, horz,
-	    width * subsample_x * sizeof (pixman_fixed_t));
-    memcpy (params + 4 + width * subsample_x, vert,
-	    height * subsample_y * sizeof (pixman_fixed_t));
-
-out:
-    free (horz);
-    free (vert);
+    create_1d_filter (width, reconstruct_x, sample_x, sx, subsample_x,
+		      params + 4);
+    create_1d_filter (height, reconstruct_y, sample_y, sy, subsample_y,
+		      params + 4 + width * subsample_x);
 
 #ifdef PIXMAN_GNUPLOT
     gnuplot_filter(width, subsample_x, params + 4);
-- 
1.9.1