[Pixman] [PATCH v10 06/15] 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

Signed-off-by: Bill Spitzak <spitzak at gmail.com>

Reviewed-by: Oded Gabbay <oded.gabbay at gmail.com>
---
 pixman/pixman-filter.c | 59 ++++++++++++++++++++++----------------------------
 1 file changed, 26 insertions(+), 33 deletions(-)

diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
index acfb110..6c077b6 100644
--- a/pixman/pixman-filter.c
+++ b/pixman/pixman-filter.c
@@ -217,23 +217,17 @@ integral (pixman_kernel_t reconstruct, 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           size,
-		  int              n_phases)
+		  int              n_phases,
+		  pixman_fixed_t *p)
 {
-    pixman_fixed_t *params, *p;
     double step;
     int i;
 
-    *width = ceil (size * filters[sample].width + filters[reconstruct].width);
-
-    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)
@@ -248,8 +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)
@@ -277,7 +271,7 @@ create_1d_filter (int             *width,
         }
 
 	/* Normalize */
-	p -= *width;
+	p -= width;
         total = 1 / total;
         new_total = 0;
 	for (x = x1; x < x2; ++x)
@@ -289,10 +283,8 @@ 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;
 }
 
 #ifdef PIXMAN_GNUPLOT
@@ -336,6 +328,14 @@ gnuplot_filter(int width, int samples, const pixman_fixed_t* p)
 }
 #endif
 
+/* Besides calculating the width, this can modify the scale and subsample_bits */
+static int
+filter_width(pixman_kernel_t reconstruct, pixman_kernel_t sample,
+	     double* size, int* subsample_bits)
+{
+    return ceil (filters[reconstruct].width + *size * filters[sample].width);
+}
+
 /* Create the parameter list for a SEPARABLE_CONVOLUTION filter
  * with the given kernels and size parameters
  */
@@ -352,42 +352,35 @@ pixman_filter_create_separable_convolution (int             *n_values,
 {
     double sx = fabs (pixman_fixed_to_double (size_x));
     double sy = fabs (pixman_fixed_to_double (size_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_bits_x);
     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_bits_y);
+    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));
+    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);
 #endif
 
-out:
-    free (horz);
-    free (vert);
-
     return params;
 }
-- 
1.9.1