[FFmpeg-cvslog] avcodec/put_bits: Implement put_bits32() in a single pass instead of 2 passes writing 16bits each

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Tue Jun 13 03:18:21 2017 +0200| [4f9e958b04c69b1cebdc682b752cf6add75a0693] | committer: Michael Niedermayer

avcodec/put_bits: Implement put_bits32() in a single pass instead of 2 passes writing 16bits each

820 cpu cycles -> 660 cpu cycles for 100 put_bits32()

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4f9e958b04c69b1cebdc682b752cf6add75a0693
---

 libavcodec/put_bits.h | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index 68ed391195..9bd45cd8ba 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -209,15 +209,37 @@ static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
  */
 static void av_unused put_bits32(PutBitContext *s, uint32_t value)
 {
-    int lo = value & 0xffff;
-    int hi = value >> 16;
+    unsigned int bit_buf;
+    int bit_left;
+
+    bit_buf  = s->bit_buf;
+    bit_left = s->bit_left;
+
 #ifdef BITSTREAM_WRITER_LE
-    put_bits(s, 16, lo);
-    put_bits(s, 16, hi);
+    bit_buf |= value << (32 - bit_left);
+    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     = (uint64_t)value >> bit_left;
 #else
-    put_bits(s, 16, hi);
-    put_bits(s, 16, lo);
+    bit_buf     = (uint64_t)bit_buf << bit_left;
+    bit_buf    |= value >> (32 - bit_left);
+    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_buf     = value;
 #endif
+
+    s->bit_buf  = bit_buf;
+    s->bit_left = bit_left;
 }
 
 /**