[gegl] operations: fix abyss handling of svg blend ops

[Daniel Sabo <daniels src gnome org>]

commit 75930e53e434e79b7f7460877ab4e549862f7c07
Author: Daniel Sabo <DanielSabo gmail com>
Date:   Mon Oct 7 01:41:37 2013 -0700

    operations: fix abyss handling of svg blend ops
    
    Always process abyss pixels of svg:dst, svg:dst-over,
    svg:dst-out, and svg:src-atop.

 operations/generated/clear.c               |   42 ++++++-----
 operations/generated/dst-atop.c            |   42 ++++++-----
 operations/generated/dst-in.c              |   42 ++++++-----
 operations/generated/dst-out.c             |   66 +++++++++++-----
 operations/generated/dst-over.c            |   66 +++++++++++-----
 operations/generated/dst.c                 |   66 +++++++++++-----
 operations/generated/src-atop.c            |   66 +++++++++++-----
 operations/generated/src-in.c              |    2 +-
 operations/generated/src-out.c             |   42 ++++++-----
 operations/generated/src.c                 |   42 ++++++-----
 operations/generated/svg-12-porter-duff.rb |  112 ++++++++++++++++++++--------
 operations/generated/xor.c                 |   66 +++++++++++-----
 12 files changed, 416 insertions(+), 238 deletions(-)
---
diff --git a/operations/generated/clear.c b/operations/generated/clear.c
index be84688..e0daae3 100644
--- a/operations/generated/clear.c
+++ b/operations/generated/clear.c
@@ -66,30 +66,32 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
+  if (!aux)
     return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  else
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = 0.0f;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = 0.0f;
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = 0.0f;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = 0.0f;
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/dst-atop.c b/operations/generated/dst-atop.c
index 145d41c..99fd762 100644
--- a/operations/generated/dst-atop.c
+++ b/operations/generated/dst-atop.c
@@ -66,30 +66,32 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
+  if (!aux)
     return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  else
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aA;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cB * aA + cA * (1.0f - aB);
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aA;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cB * aA + cA * (1.0f - aB);
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/dst-in.c b/operations/generated/dst-in.c
index 22508d9..98135bc 100644
--- a/operations/generated/dst-in.c
+++ b/operations/generated/dst-in.c
@@ -66,30 +66,32 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
+  if (!aux)
     return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  else
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aA * aB;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cB * aA;
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aA * aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cB * aA;
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/dst-out.c b/operations/generated/dst-out.c
index 76ce7a1..94e9c22 100644
--- a/operations/generated/dst-out.c
+++ b/operations/generated/dst-out.c
@@ -66,30 +66,54 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
-    return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  if (!aux)
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aB * (1.0f - aA);
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cB * (1.0f - aA);
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = 0.0f;
+          aD = aB * (1.0f - aA);
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = 0.0f;
+              out[j] = cB * (1.0f - aA);
+            }
+          out[3] = aD;
+          in  += 4;
+          out += 4;
+        }
+    }
+  else
+    {
+      for (i = 0; i < n_pixels; i++)
+        {
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aB * (1.0f - aA);
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cB * (1.0f - aA);
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/dst-over.c b/operations/generated/dst-over.c
index 9f12711..37399a1 100644
--- a/operations/generated/dst-over.c
+++ b/operations/generated/dst-over.c
@@ -66,30 +66,54 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
-    return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  if (!aux)
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aA + aB - aA * aB;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cB + cA * (1.0f - aB);
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = 0.0f;
+          aD = aA + aB - aA * aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = 0.0f;
+              out[j] = cB + cA * (1.0f - aB);
+            }
+          out[3] = aD;
+          in  += 4;
+          out += 4;
+        }
+    }
+  else
+    {
+      for (i = 0; i < n_pixels; i++)
+        {
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aA + aB - aA * aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cB + cA * (1.0f - aB);
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/dst.c b/operations/generated/dst.c
index c858ccf..8ec7d5d 100644
--- a/operations/generated/dst.c
+++ b/operations/generated/dst.c
@@ -66,30 +66,54 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
-    return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  if (!aux)
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aB;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cB;
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = 0.0f;
+          aD = aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = 0.0f;
+              out[j] = cB;
+            }
+          out[3] = aD;
+          in  += 4;
+          out += 4;
+        }
+    }
+  else
+    {
+      for (i = 0; i < n_pixels; i++)
+        {
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cB;
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/src-atop.c b/operations/generated/src-atop.c
index ff625fa..87b9f55 100644
--- a/operations/generated/src-atop.c
+++ b/operations/generated/src-atop.c
@@ -66,30 +66,54 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
-    return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  if (!aux)
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aB;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cA * aB + cB * (1.0f - aA);
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = 0.0f;
+          aD = aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = 0.0f;
+              out[j] = cA * aB + cB * (1.0f - aA);
+            }
+          out[3] = aD;
+          in  += 4;
+          out += 4;
+        }
+    }
+  else
+    {
+      for (i = 0; i < n_pixels; i++)
+        {
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cA * aB + cB * (1.0f - aA);
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/src-in.c b/operations/generated/src-in.c
index 7fff470..f082820 100644
--- a/operations/generated/src-in.c
+++ b/operations/generated/src-in.c
@@ -66,7 +66,7 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
+  if (!aux)
     return TRUE;
 
   for (i = 0; i < n_pixels; i++)
diff --git a/operations/generated/src-out.c b/operations/generated/src-out.c
index bb2359e..c188d17 100644
--- a/operations/generated/src-out.c
+++ b/operations/generated/src-out.c
@@ -66,30 +66,32 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
+  if (!aux)
     return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  else
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aA * (1.0f - aB);
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cA * (1.0f - aB);
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aA * (1.0f - aB);
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cA * (1.0f - aB);
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/src.c b/operations/generated/src.c
index d8c8179..c23946b 100644
--- a/operations/generated/src.c
+++ b/operations/generated/src.c
@@ -66,30 +66,32 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
+  if (!aux)
     return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  else
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aA;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cA;
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aA;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cA;
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
diff --git a/operations/generated/svg-12-porter-duff.rb b/operations/generated/svg-12-porter-duff.rb
index 762c937..22de28b 100755
--- a/operations/generated/svg-12-porter-duff.rb
+++ b/operations/generated/svg-12-porter-duff.rb
@@ -34,28 +34,39 @@ copyright = '
 
 a = [
       ['clear',         '0.0f',
-                        '0.0f'],
+                        '0.0f',
+       false],
       ['src',           'cA',
-                        'aA'],
+                        'aA',
+       false],
       ['dst',           'cB',
-                        'aB'],
+                        'aB',
+       true],
 #      ['src_over',      'cA + cB * (1.0f - aA)',
-#                        'aA + aB - aA * aB'],
+#                        'aA + aB - aA * aB',
+#       false],
       ['dst_over',      'cB + cA * (1.0f - aB)',
-                        'aA + aB - aA * aB'],
+                        'aA + aB - aA * aB',
+       true],
       ['dst_in',        'cB * aA', # <- XXX: typo?
-                        'aA * aB'],
+                        'aA * aB',
+       false],
       ['src_out',       'cA * (1.0f - aB)',
-                        'aA * (1.0f - aB)'],
+                        'aA * (1.0f - aB)',
+       false],
       ['dst_out',       'cB * (1.0f - aA)',
-                        'aB * (1.0f - aA)'],
+                        'aB * (1.0f - aA)',
+       true],
       ['src_atop',      'cA * aB + cB * (1.0f - aA)',
-                        'aB'],
+                        'aB',
+       true],
 
       ['dst_atop',      'cB * aA + cA * (1.0f - aB)',
-                        'aA'],
+                        'aA',
+       false],
       ['xor',           'cA * (1.0f - aB)+ cB * (1.0f - aA)',
-                        'aA + aB - 2.0f * aA * aB'],
+                        'aA + aB - 2.0f * aA * aB',
+       true],
     ]
 
 b = [ ['src_in',        'cA * aB',  # the bounding box of this mode is the
@@ -96,9 +107,6 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED in = in_buf;
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
-
-  if (aux==NULL)
-    return TRUE;
 '
 
 file_tail1 = '
@@ -148,28 +156,65 @@ a.each do
 #include \"gegl-chant.h\"
 "
     file.write file_head2
-    file.write "
-  for (i = 0; i < n_pixels; i++)
-    {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
 
-      aB = in[3];
-      aA = aux[3];
-      aD = #{a_formula};
-
-      for (j = 0; j < 3; j++)
+    if item[3]
+      file.write "
+  if (!aux)
+    {
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = 0.0f;
+          aD = #{a_formula};
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = 0.0f;
+              out[j] = #{c_formula};
+            }
+          out[3] = aD;
+          in  += 4;
+          out += 4;
+        }
+    }
+  else"
+    else
+      file.write "
+  if (!aux)
+    return TRUE;
+  else"
+    end
 
-          cB = in[j];
-          cA = aux[j];
-          out[j] = #{c_formula};
+    file.write "
+    {
+      for (i = 0; i < n_pixels; i++)
+        {
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = #{a_formula};
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = #{c_formula};
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }
@@ -217,6 +262,9 @@ b.each do
 "
     file.write file_head2
     file.write "
+  if (!aux)
+    return TRUE;
+
   for (i = 0; i < n_pixels; i++)
     {
       gint   j;
diff --git a/operations/generated/xor.c b/operations/generated/xor.c
index 6c93d1d..c079de5 100644
--- a/operations/generated/xor.c
+++ b/operations/generated/xor.c
@@ -66,30 +66,54 @@ process (GeglOperation        *op,
   gfloat * GEGL_ALIGNED aux = aux_buf;
   gfloat * GEGL_ALIGNED out = out_buf;
 
-  if (aux==NULL)
-    return TRUE;
-
-  for (i = 0; i < n_pixels; i++)
+  if (!aux)
     {
-      gint   j;
-      gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
-
-      aB = in[3];
-      aA = aux[3];
-      aD = aA + aB - 2.0f * aA * aB;
-
-      for (j = 0; j < 3; j++)
+      for (i = 0; i < n_pixels; i++)
         {
-          gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
-
-          cB = in[j];
-          cA = aux[j];
-          out[j] = cA * (1.0f - aB)+ cB * (1.0f - aA);
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = 0.0f;
+          aD = aA + aB - 2.0f * aA * aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = 0.0f;
+              out[j] = cA * (1.0f - aB)+ cB * (1.0f - aA);
+            }
+          out[3] = aD;
+          in  += 4;
+          out += 4;
+        }
+    }
+  else
+    {
+      for (i = 0; i < n_pixels; i++)
+        {
+          gint   j;
+          gfloat aA G_GNUC_UNUSED, aB G_GNUC_UNUSED, aD G_GNUC_UNUSED;
+
+          aB = in[3];
+          aA = aux[3];
+          aD = aA + aB - 2.0f * aA * aB;
+
+          for (j = 0; j < 3; j++)
+            {
+              gfloat cA G_GNUC_UNUSED, cB G_GNUC_UNUSED;
+
+              cB = in[j];
+              cA = aux[j];
+              out[j] = cA * (1.0f - aB)+ cB * (1.0f - aA);
+            }
+          out[3] = aD;
+          in  += 4;
+          aux += 4;
+          out += 4;
         }
-      out[3] = aD;
-      in  += 4;
-      aux += 4;
-      out += 4;
     }
   return TRUE;
 }