[babl] extensions: speed up 8bit gray scale for GIMP

[Øyvind Kolås <ok src gnome org>]

commit 75429d2f0b63833a0fde3da1442aa08018ea8750
Author: Øyvind Kolås <pippin gimp org>
Date:   Fri Dec 9 14:26:31 2016 +0100

    extensions: speed up 8bit gray scale for GIMP

 extensions/gimp-8bit.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/extensions/gimp-8bit.c b/extensions/gimp-8bit.c
index d3e9522..55bd95c 100644
--- a/extensions/gimp-8bit.c
+++ b/extensions/gimp-8bit.c
@@ -229,6 +229,24 @@ conv_ga8_gamma_2_2_gaF_linear (unsigned char *src,
 }
 
 static INLINE long
+conv_ga8_gamma_2_2_rgba8_gamma_2_2 (unsigned char *src,
+                                    unsigned char *dst,
+                                    long           samples)
+{
+  long   n = samples;
+
+  while (n--)
+    {
+      *dst++ = *src;
+      *dst++ = *src;
+      *dst++ = *src++;
+      *dst++ = *src++;
+    }
+
+  return samples;
+}
+
+static INLINE long
 conv_ga8_linear_rgbaF_linear (unsigned char *src,
                               unsigned char *dst,
                               long           samples)
@@ -496,6 +514,8 @@ init (void)
   o (ga8_linear, rgbaF_linear);
   o (ga8_gamma_2_2, rgbaF_linear);
 
+  o (ga8_gamma_2_2, rgba8_gamma_2_2);
+
   o (g8_linear, gF_linear);
   o (g8_gamma_2_2, gF_linear);
   o (g8_linear, rgbaF_linear);