Add optional suffix _generic to generic SDL_cond impl

Allows for runtime selectable implementation

src/thread/windows/SDL_syscond_srw.c

@@ -0,0 +1,102 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "../../SDL_internal.h"
+
+#include "SDL_hints.h"
+#include "SDL_thread.h"
+
+#include "../generic/SDL_syscond_c.h"
+
+typedef SDL_cond * (*pfnSDL_CreateCond)(void);
+typedef void (*pfnSDL_DestroyCond)(SDL_cond *);
+typedef int (*pfnSDL_CondSignal)(SDL_cond *);
+typedef int (*pfnSDL_CondBroadcast)(SDL_cond *);
+typedef int (*pfnSDL_CondWait)(SDL_cond *, SDL_mutex *);
+typedef int (*pfnSDL_CondWaitTimeout)(SDL_cond *, SDL_mutex *, Uint32);
+
+typedef struct SDL_cond_impl_t
+{
+    pfnSDL_CreateCond       Create;
+    pfnSDL_DestroyCond      Destroy;
+    pfnSDL_CondSignal       Signal;
+    pfnSDL_CondBroadcast    Broadcast;
+    pfnSDL_CondWait         Wait;
+    pfnSDL_CondWaitTimeout  WaitTimeout;
+} SDL_cond_impl_t;
+
+/* Implementation will be chosen at runtime based on available Kernel features */
+static SDL_cond_impl_t SDL_cond_impl_active = {0};
+
+/**
+ * Generic Condition Variable implementation using SDL_mutex and SDL_sem
+ */
+
+static const SDL_cond_impl_t SDL_cond_impl_generic =
+{
+    &SDL_CreateCond_generic,
+    &SDL_DestroyCond_generic,
+    &SDL_CondSignal_generic,
+    &SDL_CondBroadcast_generic,
+    &SDL_CondWait_generic,
+    &SDL_CondWaitTimeout_generic,
+};
+
+
+SDL_cond *
+SDL_CreateCond(void)
+{
+    if (SDL_cond_impl_active.Create == NULL) {
+        SDL_memcpy(&SDL_cond_impl_active, &SDL_cond_impl_generic, sizeof(SDL_cond_impl_active));
+    }
+    return SDL_cond_impl_active.Create();
+}
+
+void
+SDL_DestroyCond(SDL_cond * cond)
+{
+    SDL_cond_impl_active.Destroy(cond);
+}
+
+int
+SDL_CondSignal(SDL_cond * cond)
+{
+    return SDL_cond_impl_active.Signal(cond);
+}
+
+int
+SDL_CondBroadcast(SDL_cond * cond)
+{
+    return SDL_cond_impl_active.Broadcast(cond);
+}
+
+int
+SDL_CondWaitTimeout(SDL_cond * cond, SDL_mutex * mutex, Uint32 ms)
+{
+    return SDL_cond_impl_active.WaitTimeout(cond, mutex, ms);
+}
+
+int
+SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex)
+{
+    return SDL_cond_impl_active.Wait(cond, mutex);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */