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authorRonald S. Bultje <rsbultje@gmail.com>2012-07-22 20:46:10 -0700
committerLuca Barbato <lu_zero@gentoo.org>2012-07-23 16:27:53 +0200
commit58db34aa1e6c4cb1d876d0abc497c5e902da857e (patch)
treee767c1f38d5b3615eb0088b30caa035b7cd2d81c
parent08cd95e8a37674401ed24e5e6f4f7402edb7fdeb (diff)
downloadffmpeg-58db34aa1e6c4cb1d876d0abc497c5e902da857e.tar.gz
h264: refactor NAL decode loop
Write out the NAL decoding loops in full so that they are easier to parse for a preprocessor without it having to be aware of macros or other such things in C code. This also makes the code more readable. Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
-rw-r--r--libavcodec/h264.c42
1 files changed, 25 insertions, 17 deletions
diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index a4afcc870e..dcb9e00c43 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -175,42 +175,50 @@ const uint8_t *ff_h264_decode_nal(H264Context *h, const uint8_t *src,
src++;
length--;
+#define STARTCODE_TEST \
+ if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) { \
+ if (src[i + 2] != 3) { \
+ /* startcode, so we must be past the end */ \
+ length = i; \
+ } \
+ break; \
+ }
#if HAVE_FAST_UNALIGNED
+#define FIND_FIRST_ZERO \
+ if (i > 0 && !src[i]) \
+ i--; \
+ while (src[i]) \
+ i++
#if HAVE_FAST_64BIT
-#define RS 7
for (i = 0; i + 1 < length; i += 9) {
if (!((~AV_RN64A(src + i) &
(AV_RN64A(src + i) - 0x0100010001000101ULL)) &
0x8000800080008080ULL))
+ continue;
+ FIND_FIRST_ZERO;
+ STARTCODE_TEST;
+ i -= 7;
+ }
#else
-#define RS 3
for (i = 0; i + 1 < length; i += 5) {
if (!((~AV_RN32A(src + i) &
(AV_RN32A(src + i) - 0x01000101U)) &
0x80008080U))
-#endif
continue;
- if (i > 0 && !src[i])
- i--;
- while (src[i])
- i++;
+ FIND_FIRST_ZERO;
+ STARTCODE_TEST;
+ i -= 3;
+ }
+#endif
#else
-#define RS 0
for (i = 0; i + 1 < length; i += 2) {
if (src[i])
continue;
if (i > 0 && src[i - 1] == 0)
i--;
-#endif
- if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) {
- if (src[i + 2] != 3) {
- /* startcode, so we must be past the end */
- length = i;
- }
- break;
- }
- i -= RS;
+ STARTCODE_TEST;
}
+#endif
if (i >= length - 1) { // no escaped 0
*dst_length = length;