[Mesa-dev] [PATCH 04/29] intel/isl: Add a helper for composing swizzles

[Jason Ekstrand]

---
 src/intel/isl/isl.c | 35 +++++++++++++++++++++++++++++++++++
 src/intel/isl/isl.h |  3 +++
 2 files changed, 38 insertions(+)

diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
index 4133b53..a2d3ae6 100644
--- a/src/intel/isl/isl.c
+++ b/src/intel/isl/isl.c
@@ -2344,3 +2344,38 @@ isl_swizzle_supports_rendering(const struct gen_device_info *devinfo,
              swizzle.a == ISL_CHANNEL_SELECT_ALPHA;
    }
 }
+
+static enum isl_channel_select
+swizzle_select(enum isl_channel_select chan, struct isl_swizzle swizzle)
+{
+   switch (chan) {
+   case ISL_CHANNEL_SELECT_ZERO:
+   case ISL_CHANNEL_SELECT_ONE:
+      return chan;
+   case ISL_CHANNEL_SELECT_RED:
+      return swizzle.r;
+   case ISL_CHANNEL_SELECT_GREEN:
+      return swizzle.g;
+   case ISL_CHANNEL_SELECT_BLUE:
+      return swizzle.b;
+   case ISL_CHANNEL_SELECT_ALPHA:
+      return swizzle.a;
+   default:
+      unreachable("Invalid swizzle component");
+   }
+}
+
+/**
+ * Returns the single swizzle that is equivalent to applying the two given
+ * swizzles in sequence.
+ */
+struct isl_swizzle
+isl_swizzle_compose(struct isl_swizzle first, struct isl_swizzle second)
+{
+   return (struct isl_swizzle) {
+      .r = swizzle_select(first.r, second),
+      .g = swizzle_select(first.g, second),
+      .b = swizzle_select(first.b, second),
+      .a = swizzle_select(first.a, second),
+   };
+}
diff --git a/src/intel/isl/isl.h b/src/intel/isl/isl.h
index a15ba8a..da29baa 100644
--- a/src/intel/isl/isl.h
+++ b/src/intel/isl/isl.h
@@ -1684,6 +1684,9 @@ bool
 isl_swizzle_supports_rendering(const struct gen_device_info *devinfo,
                                struct isl_swizzle swizzle);
 
+struct isl_swizzle
+isl_swizzle_compose(struct isl_swizzle first, struct isl_swizzle second);
+
 #define isl_surf_init(dev, surf, ...) \
    isl_surf_init_s((dev), (surf), \
                    &(struct isl_surf_init_info) {  __VA_ARGS__ });
-- 
2.5.0.400.gff86faf