st/mesa: move utility functions, macros into new st_util.h file

To de-clutter st_context.h.

Clean up remaining function prototypes in st_context.h.

The st_vp_uses_current_values() helper is only used in st_context.c
so move it there.

The st_get_active_states() function is only used in st_context.c so
remove its prototype in st_context.h

Reviewed-by: Neha Bhende <bhenden@vmware.com>

src/mesa/state_tracker/st_util.h

@@ -0,0 +1,114 @@
+/**************************************************************************
+ *
+ * Copyright 2019 VMware, Inc.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+
+/*
+ * Miscellantous state tracker utility functions, macros.
+ */
+
+
+#ifndef ST_UTIL
+#define ST_UTIL
+
+
+#include "state_tracker/st_context.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/** For drawing quads for glClear, glDraw/CopyPixels, glBitmap, etc. */
+struct st_util_vertex
+{
+   float x, y, z;
+   float r, g, b, a;
+   float s, t;
+};
+
+
+
+/* Invalidate the readpixels cache to ensure we don't read stale data.
+ */
+static inline void
+st_invalidate_readpix_cache(struct st_context *st)
+{
+   if (unlikely(st->readpix_cache.src)) {
+      pipe_resource_reference(&st->readpix_cache.src, NULL);
+      pipe_resource_reference(&st->readpix_cache.cache, NULL);
+   }
+}
+
+
+#define Y_0_TOP 1
+#define Y_0_BOTTOM 2
+
+static inline GLuint
+st_fb_orientation(const struct gl_framebuffer *fb)
+{
+   if (fb && _mesa_is_winsys_fbo(fb)) {
+      /* Drawing into a window (on-screen buffer).
+       *
+       * Negate Y scale to flip image vertically.
+       * The NDC Y coords prior to viewport transformation are in the range
+       * [y=-1=bottom, y=1=top]
+       * Hardware window coords are in the range [y=0=top, y=H-1=bottom] where
+       * H is the window height.
+       * Use the viewport transformation to invert Y.
+       */
+      return Y_0_TOP;
+   }
+   else {
+      /* Drawing into user-created FBO (very likely a texture).
+       *
+       * For textures, T=0=Bottom, so by extension Y=0=Bottom for rendering.
+       */
+      return Y_0_BOTTOM;
+   }
+}
+
+
+static inline bool
+st_user_clip_planes_enabled(struct gl_context *ctx)
+{
+   return (ctx->API == API_OPENGL_COMPAT ||
+           ctx->API == API_OPENGLES) && /* only ES 1.x */
+          ctx->Transform.ClipPlanesEnabled;
+}
+
+
+/** clear-alloc a struct-sized object, with casting */
+#define ST_CALLOC_STRUCT(T)   (struct T *) calloc(1, sizeof(struct T))
+
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif /* ST_UTIL */