avcodec/put_bits: Always check buffer end before writing
authorMichael Niedermayer <michael@niedermayer.cc>
Fri, 1 Jan 2016 01:41:06 +0000 (02:41 +0100)
committerMichael Niedermayer <michael@niedermayer.cc>
Sat, 2 Jan 2016 18:23:10 +0000 (19:23 +0100)
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@niedermayer.cc>
libavcodec/put_bits.h

index 5b1bc8b..0db8a03 100644 (file)
@@ -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;
     }