+// Some GPUs use very inaccurate fixed-function circuits for rounding
+// floating-point values to 8-bit outputs, leading to absurdities like
+// the roundoff point between 128 and 129 being 128.62 instead of 128.6.
+// We test, for every integer, x+0.48 and x+0.52 and check that they
+// round the right way (giving some leeway, but not a lot); the number
+// of errors are stored here.
+//
+// If this value is above 0, the extension GL_EXT_gpu_shader4 is available
+// (giving round()) and you have enabled dithering, we will round off
+// explicitly at the very end of the shader.
+//
+// Note: I don't know of any cards that round off wrong (well, outside
+// our tolerance) and do not have this extension.
+extern int movit_num_wrongly_rounded;
+extern bool movit_shader_rounding_supported;
+