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authorPeter Meerwald <pmeerw@pmeerw.net>2015-02-20 01:35:33 +0100
committerLuca Barbato <lu_zero@gentoo.org>2015-02-21 00:54:40 +0100
commitbf07d813f6c88b5a76980f321cf7272d799c4216 (patch)
tree66ce339793e2f781c08155fb45c44c4e6ac5d896
parent3fe26bb60858951710a42065c8183cce100d632a (diff)
downloadffmpeg-bf07d813f6c88b5a76980f321cf7272d799c4216.tar.gz
libavutil: Add av_clip_intp2
there already is a function, av_clip_uintp2() that clips a signed integer to an unsigned power-of-two range, i.e. 0,2^p-1 this patch adds a function av_clip_intp2() that clips a signed integer to a signed power-of-two range, i.e. -(2^p),(2^p-1) the new function can be used as a special case for av_clip(), e.g. av_clip(x, -8192, 8191) can be rewritten as av_clip_intp2(x, 13) there are ARM instructions, usat and ssat resp., which map nicely to these functions (see next patch) Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net> Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
-rw-r--r--libavutil/common.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/libavutil/common.h b/libavutil/common.h
index eb40e12990..3265f9cca4 100644
--- a/libavutil/common.h
+++ b/libavutil/common.h
@@ -153,6 +153,20 @@ static av_always_inline av_const int32_t av_clipl_int32_c(int64_t a)
}
/**
+ * Clip a signed integer into the -(2^p),(2^p-1) range.
+ * @param a value to clip
+ * @param p bit position to clip at
+ * @return clipped value
+ */
+static av_always_inline av_const int av_clip_intp2_c(int a, int p)
+{
+ if ((a + (1 << p)) & ~((1 << (p + 1)) - 1))
+ return (a >> 31) ^ ((1 << p) - 1);
+ else
+ return a;
+}
+
+/**
* Clip a signed integer to an unsigned power of two range.
* @param a value to clip
* @param p bit position to clip at
@@ -386,6 +400,9 @@ static av_always_inline av_const int av_popcount64_c(uint64_t x)
#ifndef av_clipl_int32
# define av_clipl_int32 av_clipl_int32_c
#endif
+#ifndef av_clip_intp2
+# define av_clip_intp2 av_clip_intp2_c
+#endif
#ifndef av_clip_uintp2
# define av_clip_uintp2 av_clip_uintp2_c
#endif