glx/dri2: use uint64_t instead of double to represent time for FPS calculation

Wine or a windows app changes fpucw to 0x7f, causing doubles to be equivalent
to floats, which broke the calculation of FPS.
We should be very careful about using doubles in Mesa.

Henri Verbeet adds:
  For reference, this is done by for example d3d9 when a D3D device is
  created without D3DCREATE_FPU_PRESERVE set. In the general case
  applications can do all kinds of terrible things to the FPU control
  word of course.

1 files changed, 6 insertions, 5 deletions

diff --git a/src/glx/dri2_glx.c b/src/glx/dri2_glx.c
index f2fc187329..4ff0b9ed73 100644
--- a/src/glx/dri2_glx.c
+++ b/src/glx/dri2_glx.c
@@ -112,7 +112,7 @@ struct dri2_drawable
    int have_fake_front;
    int swap_interval;
 
-   double previous_time;
+   uint64_t previous_time;
    unsigned frames;
 };
 
@@ -676,17 +676,18 @@ unsigned dri2GetSwapEventType(Display* dpy, XID drawable)
 static void show_fps(struct dri2_drawable *draw)
 {
    struct timeval tv;
-   double current_time;
+   uint64_t current_time;
 
    gettimeofday(&tv, 0);
-   current_time = (double)tv.tv_sec + (double)tv.tv_usec * 0.000001;
+   current_time = (uint64_t)tv.tv_sec*1000000 + (uint64_t)tv.tv_usec;
 
    draw->frames++;
 
-   if (draw->previous_time + 1 < current_time) {
+   if (draw->previous_time + 1000000 <= current_time) {
       if (draw->previous_time) {
          fprintf(stderr, "libGL: FPS = %.1f\n",
-                 draw->frames / (current_time - draw->previous_time));
+                 ((uint64_t)draw->frames * 1000000) /
+                 (double)(current_time - draw->previous_time));
       }
       draw->frames = 0;
       draw->previous_time = current_time;