include/SDL_cpuinfo.h
author David Ludwig <dludwig@pobox.com>
Sat, 29 Nov 2014 10:09:30 -0500
changeset 9247 eddb899239fe
parent 9003 446ed0fe0fc3
child 9619 b94b6d0bff0f
permissions -rw-r--r--
WinRT: bug and data-integrity fixes for SDL_GetPrefPath()

This change does a few things, all with regards to the WinRT implementation of
SDL_GetPrefPath():

1. it fixes a bug whereby SDL_GetPrefPath() did not create the directory it
returned. On other SDL platforms, SDL_GetPrefPath() will create separate
directories for its 'org' and 'app' folders. Without this, attempts to create
files in the pref-path would fail, unless those directories were first created
by the app, or by some other library the app used. This change makes sure
that these directories get created, before SDL_GetPrefPath() returns to its
caller(s).


2. it defaults to having SDL_GetPrefPath() return a WinRT 'Local' folder
on all platforms. Previously, for Windows Store apps, it would have used a
different, 'Roaming' folder. Files in Roaming folders can be automatically,
and synchronized across multiple devices by Windows. This synchronization can
happen while the app runs, with new files being copied into a running app's
pref-path. Unless an app is specifically designed to handle this scenario,
there is a chance that save-data could be overwritten in unwanted or
unexpected ways.

The default is now to use a Local folder, which does not get synchronized, and
which is arguably a bit safer to use. Apps that wish to use Roaming folders
can do so by setting SDL_HINT_WINRT_PREF_PATH_ROOT to "roaming", however it
is recommended that one first read Microsoft's documentation for Roaming
files, a link to which is provided in README-winrt.md.

To preserve older pref-path selection behavior (found in SDL 2.0.3, as well as
many pre-2.0.4 versions of SDL from hg.libsdl.org), which uses a Roaming path
in Windows Store apps, and a Local path in Windows Phone, set
SDL_HINT_WINRT_PREF_PATH_ROOT to "old".

Please note that Roaming paths are not supported on Windows Phone 8.0, due to
limitations in the OS itself. Attempts to use this will fail.
(Windows Phone 8.1 does not have this limitation, however.)


3. It makes SDL_GetPrefPath(), when on Windows Phone 8.0, and when
SDL_HINT_WINRT_PREF_PATH_ROOT is set to "roaming", return NULL, rather than
silently defaulting to a Local path (then switching to a Roaming path if and
when the user upgraded to Windows Phone 8.1).
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 
    22 /**
    23  *  \file SDL_cpuinfo.h
    24  *
    25  *  CPU feature detection for SDL.
    26  */
    27 
    28 #ifndef _SDL_cpuinfo_h
    29 #define _SDL_cpuinfo_h
    30 
    31 #include "SDL_stdinc.h"
    32 
    33 /* Need to do this here because intrin.h has C++ code in it */
    34 /* Visual Studio 2005 has a bug where intrin.h conflicts with winnt.h */
    35 #if defined(_MSC_VER) && (_MSC_VER >= 1500) && (defined(_M_IX86) || defined(_M_X64))
    36 #include <intrin.h>
    37 #ifndef _WIN64
    38 #define __MMX__
    39 #define __3dNOW__
    40 #endif
    41 #define __SSE__
    42 #define __SSE2__
    43 #elif defined(__MINGW64_VERSION_MAJOR)
    44 #include <intrin.h>
    45 #else
    46 #ifdef __ALTIVEC__
    47 #if HAVE_ALTIVEC_H && !defined(__APPLE_ALTIVEC__)
    48 #include <altivec.h>
    49 #undef pixel
    50 #endif
    51 #endif
    52 #ifdef __MMX__
    53 #include <mmintrin.h>
    54 #endif
    55 #ifdef __3dNOW__
    56 #include <mm3dnow.h>
    57 #endif
    58 #ifdef __SSE__
    59 #include <xmmintrin.h>
    60 #endif
    61 #ifdef __SSE2__
    62 #include <emmintrin.h>
    63 #endif
    64 #endif
    65 
    66 #include "begin_code.h"
    67 /* Set up for C function definitions, even when using C++ */
    68 #ifdef __cplusplus
    69 extern "C" {
    70 #endif
    71 
    72 /* This is a guess for the cacheline size used for padding.
    73  * Most x86 processors have a 64 byte cache line.
    74  * The 64-bit PowerPC processors have a 128 byte cache line.
    75  * We'll use the larger value to be generally safe.
    76  */
    77 #define SDL_CACHELINE_SIZE  128
    78 
    79 /**
    80  *  This function returns the number of CPU cores available.
    81  */
    82 extern DECLSPEC int SDLCALL SDL_GetCPUCount(void);
    83 
    84 /**
    85  *  This function returns the L1 cache line size of the CPU
    86  *
    87  *  This is useful for determining multi-threaded structure padding
    88  *  or SIMD prefetch sizes.
    89  */
    90 extern DECLSPEC int SDLCALL SDL_GetCPUCacheLineSize(void);
    91 
    92 /**
    93  *  This function returns true if the CPU has the RDTSC instruction.
    94  */
    95 extern DECLSPEC SDL_bool SDLCALL SDL_HasRDTSC(void);
    96 
    97 /**
    98  *  This function returns true if the CPU has AltiVec features.
    99  */
   100 extern DECLSPEC SDL_bool SDLCALL SDL_HasAltiVec(void);
   101 
   102 /**
   103  *  This function returns true if the CPU has MMX features.
   104  */
   105 extern DECLSPEC SDL_bool SDLCALL SDL_HasMMX(void);
   106 
   107 /**
   108  *  This function returns true if the CPU has 3DNow! features.
   109  */
   110 extern DECLSPEC SDL_bool SDLCALL SDL_Has3DNow(void);
   111 
   112 /**
   113  *  This function returns true if the CPU has SSE features.
   114  */
   115 extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE(void);
   116 
   117 /**
   118  *  This function returns true if the CPU has SSE2 features.
   119  */
   120 extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE2(void);
   121 
   122 /**
   123  *  This function returns true if the CPU has SSE3 features.
   124  */
   125 extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE3(void);
   126 
   127 /**
   128  *  This function returns true if the CPU has SSE4.1 features.
   129  */
   130 extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE41(void);
   131 
   132 /**
   133  *  This function returns true if the CPU has SSE4.2 features.
   134  */
   135 extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE42(void);
   136 
   137 /**
   138  *  This function returns true if the CPU has AVX features.
   139  */
   140 extern DECLSPEC SDL_bool SDLCALL SDL_HasAVX(void);
   141 
   142 /**
   143  *  This function returns true if the CPU has AVX2 features.
   144  */
   145 extern DECLSPEC SDL_bool SDLCALL SDL_HasAVX2(void);
   146 
   147 /**
   148  *  This function returns the amount of RAM configured in the system, in MB.
   149  */
   150 extern DECLSPEC int SDLCALL SDL_GetSystemRAM(void);
   151 
   152 
   153 /* Ends C function definitions when using C++ */
   154 #ifdef __cplusplus
   155 }
   156 #endif
   157 #include "close_code.h"
   158 
   159 #endif /* _SDL_cpuinfo_h */
   160 
   161 /* vi: set ts=4 sw=4 expandtab: */