lavc: move exp2fi to ff_exp2fi in internal.h

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index 445b45ad91..afcf00d013 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -242,6 +242,25 @@ static av_always_inline int64_t ff_samples_to_time_base(AVCodecContext *avctx,
 }
 
 /**
+ * 2^(x) for integer x
+ * @return correctly rounded float
+ */
+static av_always_inline float ff_exp2fi(int x) {
+    /* Normal range */
+    if (-126 <= x && x <= 128)
+        return av_int2float(x+127 << 23);
+    /* Too large */
+    else if (x > 128)
+        return INFINITY;
+    /* Subnormal numbers */
+    else if (x > -150)
+        return av_int2float(1 << (x+149));
+    /* Negligibly small */
+    else
+        return 0;
+}
+
+/**
  * Get a buffer for a frame. This is a wrapper around
  * AVCodecContext.get_buffer() and should be used instead calling get_buffer()
  * directly.