stdlib: Add SDL_trunc and SDL_truncf

src/dynapi/SDL_dynapi_overrides.h

@@ -761,3 +761,5 @@
 #define SDL_UnlockSensors SDL_UnlockSensors_REAL
 #define SDL_Metal_GetLayer SDL_Metal_GetLayer_REAL
 #define SDL_Metal_GetDrawableSize SDL_Metal_GetDrawableSize_REAL
+#define SDL_trunc SDL_trunc_REAL
+#define SDL_truncf SDL_truncf_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -820,3 +820,5 @@ SDL_DYNAPI_PROC(void,SDL_LockSensors,(void),(),)
 SDL_DYNAPI_PROC(void,SDL_UnlockSensors,(void),(),)
 SDL_DYNAPI_PROC(void*,SDL_Metal_GetLayer,(SDL_MetalView a),(a),return)
 SDL_DYNAPI_PROC(void,SDL_Metal_GetDrawableSize,(SDL_Window *a, int *b, int *c),(a,b,c),)
+SDL_DYNAPI_PROC(double,SDL_trunc,(double a),(a),return)
+SDL_DYNAPI_PROC(float,SDL_truncf,(float a),(a),return)

src/stdlib/SDL_stdlib.c

@@ -260,6 +260,27 @@ SDL_floorf(float x)
 #endif
 }
 
+double
+SDL_trunc(double x)
+{
+#if defined(HAVE_TRUNC)
+    return trunc(x);
+#else
+    /* !!! FIXME: there are more formal (correct!) ways to do this. */
+    return (double) ((Sint64) x);
+#endif
+}
+
+float
+SDL_truncf(float x)
+{
+#if defined(HAVE_TRUNCF)
+    return truncf(x);
+#else
+    return (float)SDL_trunc((double)x);
+#endif
+}
+
 double
 SDL_fmod(double x, double y)
 {