[FFmpeg-cvslog] avcodec/put_bits: Always check buffer end before writing

[Michael Niedermayer]

ffmpeg | branch: release/2.7 | Michael Niedermayer <michael at niedermayer.cc> | Fri Jan  1 02:41:06 2016 +0100| [b65c06ee5efefe96f1dccf65c68174099ba26d7a] | committer: Michael Niedermayer

avcodec/put_bits: Always check buffer end before writing

This causes a overall slowdown of 0.1 % (tested with mpeg4 single thread encoding of matrixbench at QP=3)

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit cccb0ffccc3723acc7aab3a859b24743596dd9c0)

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b65c06ee5efefe96f1dccf65c68174099ba26d7a
---

 libavcodec/put_bits.h |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index 5b1bc8b..0db8a03 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -163,9 +163,13 @@ static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 #ifdef BITSTREAM_WRITER_LE
     bit_buf |= value << (32 - bit_left);
     if (n >= bit_left) {
-        av_assert2(s->buf_ptr+3<s->buf_end);
-        AV_WL32(s->buf_ptr, bit_buf);
-        s->buf_ptr += 4;
+        if (3 < s->buf_end - s->buf_ptr) {
+            AV_WL32(s->buf_ptr, bit_buf);
+            s->buf_ptr += 4;
+        } else {
+            av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
+            av_assert2(0);
+        }
         bit_buf     = value >> bit_left;
         bit_left   += 32;
     }
@@ -177,9 +181,13 @@ static inline void put_bits(PutBitContext *s, int n, unsigned int value)
     } else {
         bit_buf   <<= bit_left;
         bit_buf    |= value >> (n - bit_left);
-        av_assert2(s->buf_ptr+3<s->buf_end);
-        AV_WB32(s->buf_ptr, bit_buf);
-        s->buf_ptr += 4;
+        if (3 < s->buf_end - s->buf_ptr) {
+            AV_WB32(s->buf_ptr, bit_buf);
+            s->buf_ptr += 4;
+        } else {
+            av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
+            av_assert2(0);
+        }
         bit_left   += 32 - n;
         bit_buf     = value;
     }