swr: Windows-related changes

- Handle dynamic library loading for windows
- Implement swap for gdi
- fix prototypes
- update include paths on configure-based build for swr_loader.cpp

v2: split to multiple patches
v3: split and reshuffle some more; renamed title
v4: move Makefile.am changes to other commit. Modify header files

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/gallium/drivers/swr/swr_loader.cpp

@@ -25,14 +25,16 @@
 #include "util/u_dl.h"
 #include "swr_public.h"
 
+#include "pipe/p_screen.h"
+
 #include <stdio.h>
-#include <dlfcn.h>
 
 typedef pipe_screen *(*screen_create_proc)(struct sw_winsys *winsys);
 
 struct pipe_screen *
 swr_create_screen(struct sw_winsys *winsys)
 {
+   char filename[256];
    fprintf(stderr, "SWR detected ");
 
    util_dl_library *pLibrary = nullptr;
@@ -40,14 +42,15 @@ swr_create_screen(struct sw_winsys *winsys)
    util_cpu_detect();
    if (util_cpu_caps.has_avx2) {
       fprintf(stderr, "AVX2\n");
-      pLibrary = util_dl_open("libswrAVX2.so");
+      sprintf(filename, "%s%s%s", UTIL_DL_PREFIX, "swrAVX2", UTIL_DL_EXT);
    } else if (util_cpu_caps.has_avx) {
       fprintf(stderr, "AVX\n");
-      pLibrary = util_dl_open("libswrAVX.so");
+      sprintf(filename, "%s%s%s", UTIL_DL_PREFIX, "swrAVX", UTIL_DL_EXT);
    } else {
       fprintf(stderr, "no AVX/AVX2 support.  Aborting!\n");
       exit(-1);
    }
+   pLibrary = util_dl_open(filename);
 
    if (!pLibrary) {
       fprintf(stderr, "SWR library load failure: %s\n", util_dl_error());
@@ -65,3 +68,21 @@ swr_create_screen(struct sw_winsys *winsys)
 
    return pScreenCreate(winsys);
 }
+
+
+#ifdef _WIN32
+// swap function called from libl_gdi.c
+
+void
+swr_gdi_swap(struct pipe_screen *screen,
+             struct pipe_resource *res,
+             void *hDC)
+{
+   screen->flush_frontbuffer(screen,
+                             res,
+                             0, 0,
+                             hDC,
+                             NULL);
+}
+
+#endif /* _WIN32 */

src/gallium/drivers/swr/swr_public.h

@@ -38,10 +38,11 @@ struct pipe_screen *swr_create_screen(struct sw_winsys *winsys);
 // arch-specific dll entry point
 PUBLIC struct pipe_screen *swr_create_screen_internal(struct sw_winsys *winsys);
 
-struct sw_winsys *swr_get_winsys(struct pipe_screen *pipe);
-
-struct sw_displaytarget *swr_get_displaytarget(struct pipe_resource *resource);
-
+#ifdef _WIN32
+void swr_gdi_swap(struct pipe_screen *screen,
+                  struct pipe_resource *res,
+                  void *hDC);
+#endif /* _WIN32 */
 
 #ifdef __cplusplus
 }