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

[Michael Niedermayer]

From: Michael Niedermayer <mich...@niedermayer.cc>

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

Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc>
---
 libavcodec/put_bits.h |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index 5b1bc8b..69a3049 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -163,9 +163,11 @@ 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_assert0(0);
         bit_buf     = value >> bit_left;
         bit_left   += 32;
     }
@@ -177,9 +179,11 @@ 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_assert0(0);
         bit_left   += 32 - n;
         bit_buf     = value;
     }
-- 
1.7.9.5

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