+unsigned
+tesslevel_outer_components(GLenum tes_primitive_mode)
+{
+ switch (tes_primitive_mode) {
+ case GL_QUADS:
+ return 4;
+ case GL_TRIANGLES:
+ return 3;
+ case GL_ISOLINES:
+ return 2;
+ default:
+ unreachable("Bogus tessellation domain");
+ }
+ return 0;
+}
+
+unsigned
+tesslevel_inner_components(GLenum tes_primitive_mode)
+{
+ switch (tes_primitive_mode) {
+ case GL_QUADS:
+ return 2;
+ case GL_TRIANGLES:
+ return 1;
+ case GL_ISOLINES:
+ return 0;
+ default:
+ unreachable("Bogus tessellation domain");
+ }
+ return 0;
+}
+
+/**
+ * Given a normal .xyzw writemask, convert it to a writemask for a vector
+ * that's stored backwards, i.e. .wzyx.
+ */
+unsigned
+writemask_for_backwards_vector(unsigned mask)
+{
+ unsigned new_mask = 0;
+
+ for (int i = 0; i < 4; i++)
+ new_mask |= ((mask >> i) & 1) << (3 - i);
+
+ return new_mask;
+}
+