avutil: Move av_rint64_clip_* to internal.h

The function is renamed to ff_rint64_clip()

This should avoid build failures on VS2012
Feel free to changes this to a different solution

Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 37 insertions, 0 deletions

diff --git a/libavutil/internal.h b/libavutil/internal.h
index 5c2cd99dcc..8d2d8759bf 100644
--- a/libavutil/internal.h
+++ b/libavutil/internal.h
@@ -257,6 +257,43 @@ void avpriv_request_sample(void *avc,
 #endif
 
 /**
+ * Clip and convert a double value into the long long amin-amax range.
+ * This function is needed because conversion of floating point to integers when
+ * it does not fit in the integer's representation does not necessarily saturate
+ * correctly (usually converted to a cvttsd2si on x86) which saturates numbers
+ * > INT64_MAX to INT64_MIN. The standard marks such conversions as undefined
+ * behavior, allowing this sort of mathematically bogus conversions. This provides
+ * a safe alternative that is slower obviously but assures safety and better
+ * mathematical behavior.
+ * @param a value to clip
+ * @param amin minimum value of the clip range
+ * @param amax maximum value of the clip range
+ * @return clipped value
+ */
+static av_always_inline av_const int64_t ff_rint64_clip(double a, int64_t amin, int64_t amax)
+{
+    int64_t res;
+#if defined(HAVE_AV_CONFIG_H) && defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
+    if (amin > amax) abort();
+#endif
+    // INT64_MAX+1,INT64_MIN are exactly representable as IEEE doubles
+    // do range checks first
+    if (a >=  9223372036854775808.0)
+        return amax;
+    if (a <= -9223372036854775808.0)
+       return amin;
+
+    // safe to call llrint and clip accordingly
+    res = llrint(a);
+    if (res > amax)
+        return amax;
+    if (res < amin)
+        return amin;
+    return res;
+}
+
+
+/**
  * A wrapper for open() setting O_CLOEXEC.
  */
 av_warn_unused_result