update sdl2 to release https://github.com/spurious/SDL-mirror/tree/release-2.0.14

Engine/lib/sdl/Xcode-iOS/Demos/src/common.c

@@ -0,0 +1,56 @@
+/*
+ *  common.c
+ *  written by Holmes Futrell
+ *  use however you want
+ */
+
+#include "common.h"
+#include "SDL.h"
+#include <stdlib.h>
+
+/*
+    Produces a random int x, min <= x <= max
+    following a uniform distribution
+*/
+int
+randomInt(int min, int max)
+{
+    return min + rand() % (max - min + 1);
+}
+
+/*
+    Produces a random float x, min <= x <= max
+    following a uniform distribution
+ */
+float
+randomFloat(float min, float max)
+{
+    return rand() / (float) RAND_MAX *(max - min) + min;
+}
+
+void
+fatalError(const char *string)
+{
+    printf("%s: %s\n", string, SDL_GetError());
+    SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, string, SDL_GetError(), NULL);
+    exit(1);
+}
+
+static Uint64 prevTime = 0;
+
+double
+updateDeltaTime(void)
+{
+    Uint64 curTime;
+    double deltaTime;
+
+    if (prevTime == 0) {
+        prevTime = SDL_GetPerformanceCounter();
+    }
+
+    curTime = SDL_GetPerformanceCounter();
+    deltaTime = (double) (curTime - prevTime) / (double) SDL_GetPerformanceFrequency();
+    prevTime = curTime;
+
+    return deltaTime;
+}