[Mesa-dev] [PATCH 19/29] mesa: Use bitmask/ffs to iterate color material attributes.

[Mathias.Froehlich at gmx.net]

From: Mathias Fröhlich <mathias.froehlich at web.de>

Replaces an iterate and test bit in a bitmask loop by a
loop only iterating over the bits set in the bitmask.

Signed-off-by: Mathias Fröhlich <Mathias.Froehlich at web.de>
---
 src/mesa/main/light.c     | 12 +++++++-----
 src/mesa/tnl/t_vb_light.c | 11 +++++++----
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/mesa/main/light.c b/src/mesa/main/light.c
index 4773ed6..e6d71d7 100644
--- a/src/mesa/main/light.c
+++ b/src/mesa/main/light.c
@@ -711,13 +711,15 @@ _mesa_update_material( struct gl_context *ctx, GLuint bitmask )
 void
 _mesa_update_color_material( struct gl_context *ctx, const GLfloat color[4] )
 {
-   const GLbitfield bitmask = ctx->Light._ColorMaterialBitmask;
+   GLbitfield bitmask = ctx->Light._ColorMaterialBitmask;
    struct gl_material *mat = &ctx->Light.Material;
-   int i;
 
-   for (i = 0 ; i < MAT_ATTRIB_MAX ; i++) 
-      if (bitmask & (1<<i))
-	 COPY_4FV( mat->Attrib[i], color );
+   while (bitmask) {
+      int i = ffs(bitmask) - 1;
+      bitmask ^= 1u << i;
+
+      COPY_4FV( mat->Attrib[i], color );
+   }
 
    _mesa_update_material( ctx, bitmask );
 }
diff --git a/src/mesa/tnl/t_vb_light.c b/src/mesa/tnl/t_vb_light.c
index 0cdb925..40b95c3 100644
--- a/src/mesa/tnl/t_vb_light.c
+++ b/src/mesa/tnl/t_vb_light.c
@@ -231,10 +231,13 @@ prepare_materials(struct gl_context *ctx,
     * with the color pointer for each one.
     */
    if (ctx->Light.ColorMaterialEnabled) {
-      const GLuint bitmask = ctx->Light._ColorMaterialBitmask;
-      for (i = 0 ; i < MAT_ATTRIB_MAX ; i++)
-	 if (bitmask & (1<<i))
-	    VB->AttribPtr[_TNL_ATTRIB_MAT_FRONT_AMBIENT + i] = VB->AttribPtr[_TNL_ATTRIB_COLOR0];
+      GLbitfield bitmask = ctx->Light._ColorMaterialBitmask;
+      while (bitmask) {
+         int i = ffs(bitmask) - 1;
+         bitmask ^= 1u << i;
+         VB->AttribPtr[_TNL_ATTRIB_MAT_FRONT_AMBIENT + i] =
+            VB->AttribPtr[_TNL_ATTRIB_COLOR0];
+      }
    }
 
    /* Now, for each material attribute that's tracking vertex color, save
-- 
2.5.5