Added a README file regarding WinRT support

To note, this file is currently formatted with CRLF line endings, rather than
LF, to allow the file to be viewed with Notepad.

src/timer/unix/SDL_systimer.c

@@ -0,0 +1,217 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2014 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"
+
+#ifdef SDL_TIMER_UNIX
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "SDL_timer.h"
+
+/* The clock_gettime provides monotonous time, so we should use it if
+   it's available. The clock_gettime function is behind ifdef
+   for __USE_POSIX199309
+   Tommi Kyntola (tommi.kyntola@ray.fi) 27/09/2005
+*/
+/* Reworked monotonic clock to not assume the current system has one
+   as not all linux kernels provide a monotonic clock (yeah recent ones
+   probably do)
+   Also added OS X Monotonic clock support
+   Based on work in https://github.com/ThomasHabets/monotonic_clock
+ */
+#if HAVE_NANOSLEEP || HAVE_CLOCK_GETTIME
+#include <time.h>
+#endif
+#ifdef __APPLE__
+#include <mach/mach_time.h>
+#endif
+
+/* The first ticks value of the application */
+#if HAVE_CLOCK_GETTIME
+static struct timespec start_ts;
+#elif defined(__APPLE__)
+static uint64_t start_mach;
+mach_timebase_info_data_t mach_base_info;
+#endif
+static SDL_bool has_monotonic_time = SDL_FALSE;
+static struct timeval start_tv;
+static SDL_bool ticks_started = SDL_FALSE;
+
+void
+SDL_TicksInit(void)
+{
+    if (ticks_started) {
+        return;
+    }
+    ticks_started = SDL_TRUE;
+
+    /* Set first ticks value */
+#if HAVE_CLOCK_GETTIME
+    if (clock_gettime(CLOCK_MONOTONIC, &start_ts) == 0) {
+        has_monotonic_time = SDL_TRUE;
+    } else
+#elif defined(__APPLE__)
+    kern_return_t ret = mach_timebase_info(&mach_base_info);
+    if (ret == 0) {
+        has_monotonic_time = SDL_TRUE;
+        start_mach = mach_absolute_time();
+    } else
+#endif
+    {
+        gettimeofday(&start_tv, NULL);
+    }
+}
+
+void
+SDL_TicksQuit(void)
+{
+    ticks_started = SDL_FALSE;
+}
+
+Uint32
+SDL_GetTicks(void)
+{
+    Uint32 ticks;
+    if (!ticks_started) {
+        SDL_TicksInit();
+    }
+
+    if (has_monotonic_time) {
+#if HAVE_CLOCK_GETTIME
+        struct timespec now;
+        clock_gettime(CLOCK_MONOTONIC, &now);
+        ticks = (now.tv_sec - start_ts.tv_sec) * 1000 + (now.tv_nsec -
+                                                 start_ts.tv_nsec) / 1000000;
+#elif defined(__APPLE__)
+        uint64_t now = mach_absolute_time();
+        ticks = (((now - start_mach) * mach_base_info.numer) / mach_base_info.denom) / 1000000;
+#endif
+    } else {
+        struct timeval now;
+
+        gettimeofday(&now, NULL);
+        ticks =
+            (now.tv_sec - start_tv.tv_sec) * 1000 + (now.tv_usec -
+                                                  start_tv.tv_usec) / 1000;
+    }
+    return (ticks);
+}
+
+Uint64
+SDL_GetPerformanceCounter(void)
+{
+    Uint64 ticks;
+    if (!ticks_started) {
+        SDL_TicksInit();
+    }
+
+    if (has_monotonic_time) {
+#if HAVE_CLOCK_GETTIME
+        struct timespec now;
+
+        clock_gettime(CLOCK_MONOTONIC, &now);
+        ticks = now.tv_sec;
+        ticks *= 1000000000;
+        ticks += now.tv_nsec;
+#elif defined(__APPLE__)
+        ticks = mach_absolute_time();
+#endif
+    } else {
+        struct timeval now;
+
+        gettimeofday(&now, NULL);
+        ticks = now.tv_sec;
+        ticks *= 1000000;
+        ticks += now.tv_usec;
+    }
+    return (ticks);
+}
+
+Uint64
+SDL_GetPerformanceFrequency(void)
+{
+    if (!ticks_started) {
+        SDL_TicksInit();
+    }
+
+    if (has_monotonic_time) {
+#if HAVE_CLOCK_GETTIME
+        return 1000000000;
+#elif defined(__APPLE__)
+        Uint64 freq = mach_base_info.denom;
+        freq *= 1000000000;
+        freq /= mach_base_info.numer;
+        return freq;
+#endif
+    } 
+        
+    return 1000000;
+}
+
+void
+SDL_Delay(Uint32 ms)
+{
+    int was_error;
+
+#if HAVE_NANOSLEEP
+    struct timespec elapsed, tv;
+#else
+    struct timeval tv;
+    Uint32 then, now, elapsed;
+#endif
+
+    /* Set the timeout interval */
+#if HAVE_NANOSLEEP
+    elapsed.tv_sec = ms / 1000;
+    elapsed.tv_nsec = (ms % 1000) * 1000000;
+#else
+    then = SDL_GetTicks();
+#endif
+    do {
+        errno = 0;
+
+#if HAVE_NANOSLEEP
+        tv.tv_sec = elapsed.tv_sec;
+        tv.tv_nsec = elapsed.tv_nsec;
+        was_error = nanosleep(&tv, &elapsed);
+#else
+        /* Calculate the time interval left (in case of interrupt) */
+        now = SDL_GetTicks();
+        elapsed = (now - then);
+        then = now;
+        if (elapsed >= ms) {
+            break;
+        }
+        ms -= elapsed;
+        tv.tv_sec = ms / 1000;
+        tv.tv_usec = (ms % 1000) * 1000;
+
+        was_error = select(0, NULL, NULL, NULL, &tv);
+#endif /* HAVE_NANOSLEEP */
+    } while (was_error && (errno == EINTR));
+}
+
+#endif /* SDL_TIMER_UNIX */
+
+/* vi: set ts=4 sw=4 expandtab: */