mesa/st: support lowering multi-planar YUV

Support multi-planar YUV for external EGLImage's (currently just in the
dma-buf import path) by lowering to multiple texture fetch's for each
plane and CSC in shader.

There was some discussion of alternative approaches for tracking the
additional UV or U/V planes:

  https://lists.freedesktop.org/archives/mesa-dev/2016-September/127832.html

They all seemed worse than pipe_resource::next

Signed-off-by: Rob Clark <robdclark@gmail.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 85aeb1e..ee811ff 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -45,6 +45,7 @@
 #include "compiler/shader_enums.h"
 #include "main/formats.h"       /* MESA_FORMAT_COUNT */
 #include "compiler/glsl/list.h"
+#include "util/bitscan.h"
 
 
 #ifdef __cplusplus
@@ -1929,6 +1930,7 @@ struct gl_program
    GLbitfield TexturesUsed[MAX_COMBINED_TEXTURE_IMAGE_UNITS];  /**< TEXTURE_x_BIT bitmask */
    GLbitfield SamplersUsed;   /**< Bitfield of which samplers are used */
    GLbitfield ShadowSamplers; /**< Texture units used for shadow sampling. */
+   GLbitfield ExternalSamplersUsed; /**< Texture units used for samplerExternalOES */
 
    GLboolean UsesGather; /**< Does this program use gather4 at all? */
 
@@ -2460,6 +2462,20 @@ struct gl_linked_shader
    struct gl_shader_info info;
 };
 
+static inline GLbitfield gl_external_samplers(struct gl_linked_shader *shader)
+{
+   GLbitfield external_samplers = 0;
+   GLbitfield mask = shader->active_samplers;
+
+   while (mask) {
+      int idx = u_bit_scan(&mask);
+      if (shader->SamplerTargets[idx] == TEXTURE_EXTERNAL_INDEX)
+         external_samplers |= (1 << idx);
+   }
+
+   return external_samplers;
+}
+
 /**
  * A GLSL shader object.
  */