Don't clobber refcounting in SDL_Init.

       - Fixes bug 1712 by not overwriting SDL_SubsystemRefCount in SDL_Init.
       - Removes the SDL_initialized variable, and makes SDL_SubsystemRefCount
         the canonical source of truth for whether or not a subsystem has been
         initialized.
       - Refactors SDL_InitSubSystem and SDL_QuitSubSystem to use helper
         functions to manage refcount.
       - Adds automated tests for SDL_Init/Quit*.
       - Adds SDL_bits.h which contains SDL_MostSignificantBitIndex.

1 files changed, 102 insertions, 0 deletions

diff --git a/include/SDL_bits.h b/include/SDL_bits.h
new file mode 100644
index 000000000..2b1118dbb
--- /dev/null
+++ b/include/SDL_bits.h
@@ -0,0 +1,102 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2013 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.
+*/
+
+/**
+ *  \file SDL_bits.h
+ *
+ *  Functions for fiddling with bits and bitmasks.
+ */
+
+#ifndef _SDL_bits_h
+#define _SDL_bits_h
+
+#include "SDL_stdinc.h"
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+/* *INDENT-OFF* */
+extern "C" {
+/* *INDENT-ON* */
+#endif
+
+/**
+ *  \file SDL_bits.h
+ *
+ *  Uses inline functions for compilers that support them, and static
+ *  functions for those that do not.  Because these functions become
+ *  static for compilers that do not support inline functions, this
+ *  header should only be included in files that actually use them.
+ */
+
+/**
+ *  Get the index of the most significant bit. Result is undefined when called
+ *  with 0. This operation can also be stated as "count leading zeroes" and
+ *  "log base 2".
+ *
+ *  \return Index of the most significant bit.
+ */
+static __inline__ Sint8
+SDL_MostSignificantBitIndex32(Uint32 x)
+{
+#if defined(__GNUC__)
+    /* Count Leading Zeroes builtin in GCC.
+     * http://gcc.gnu.org/onlinedocs/gcc-4.3.4/gcc/Other-Builtins.html
+     */
+    return 31 - __builtin_clz(x);
+#else
+    /* Based off of Bit Twiddling Hacks by Sean Eron Anderson
+     * <seander@cs.stanford.edu>, released in the public domain.
+     * http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogLookup
+     */
+    static const Sint8 LogTable256[256] =
+    {
+    #define LT(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n
+        -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
+        LT(4), LT(5), LT(5), LT(6), LT(6), LT(6), LT(6),
+        LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7)
+    #undef LT
+    };
+
+    register unsigned int t, tt;
+
+    if (tt = x >> 16)
+    {
+      return ((t = tt >> 8) ? 24 + LogTable256[t] : 16 + LogTable256[tt]);
+    }
+    else
+    {
+      return ((t = x >> 8) ? 8 + LogTable256[t] : LogTable256[x]);
+    }
+#endif
+}
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+/* *INDENT-OFF* */
+}
+/* *INDENT-ON* */
+#endif
+#include "close_code.h"
+
+#endif /* _SDL_bits_h */
+
+/* vi: set ts=4 sw=4 expandtab: */