[FFmpeg-devel] [PATCH 1/2] avcodec/put_bits: Parametrize bit buffer type
Steinar H. Gunderson
steinar+ffmpeg at gunderson.no
Fri Jul 17 22:41:19 EEST 2020
Preparatory patch for making the bit buffer different size on different
platforms; make a typedef and make all the hardcoded sizes into expressions
deriving from this size.
No functional change; generated assembler is near-identical.
---
libavcodec/put_bits.h | 95 +++++++++++++++++++++++--------------------
1 file changed, 52 insertions(+), 43 deletions(-)
diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index 7d11a3576a..c6a8f3ac14 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -32,8 +32,14 @@
#include "libavutil/intreadwrite.h"
#include "libavutil/avassert.h"
+typedef uint32_t BitBuf;
+#define AV_WBBUF AV_WB32
+#define AV_WLBUF AV_WL32
+
+static const int BUF_BITS = 8 * sizeof(BitBuf);
+
typedef struct PutBitContext {
- uint32_t bit_buf;
+ BitBuf bit_buf;
int bit_left;
uint8_t *buf, *buf_ptr, *buf_end;
int size_in_bits;
@@ -57,7 +63,7 @@ static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
s->buf = buffer;
s->buf_end = s->buf + buffer_size;
s->buf_ptr = s->buf;
- s->bit_left = 32;
+ s->bit_left = BUF_BITS;
s->bit_buf = 0;
}
@@ -66,7 +72,7 @@ static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
*/
static inline int put_bits_count(PutBitContext *s)
{
- return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
+ return (s->buf_ptr - s->buf) * 8 + BUF_BITS - s->bit_left;
}
/**
@@ -92,7 +98,7 @@ static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer,
*/
static inline int put_bits_left(PutBitContext* s)
{
- return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
+ return (s->buf_end - s->buf_ptr) * 8 - BUF_BITS + s->bit_left;
}
/**
@@ -101,33 +107,33 @@ static inline int put_bits_left(PutBitContext* s)
static inline void flush_put_bits(PutBitContext *s)
{
#ifndef BITSTREAM_WRITER_LE
- if (s->bit_left < 32)
+ if (s->bit_left < BUF_BITS)
s->bit_buf <<= s->bit_left;
#endif
- while (s->bit_left < 32) {
+ while (s->bit_left < BUF_BITS) {
av_assert0(s->buf_ptr < s->buf_end);
#ifdef BITSTREAM_WRITER_LE
*s->buf_ptr++ = s->bit_buf;
s->bit_buf >>= 8;
#else
- *s->buf_ptr++ = s->bit_buf >> 24;
+ *s->buf_ptr++ = s->bit_buf >> (BUF_BITS - 8);
s->bit_buf <<= 8;
#endif
s->bit_left += 8;
}
- s->bit_left = 32;
+ s->bit_left = BUF_BITS;
s->bit_buf = 0;
}
static inline void flush_put_bits_le(PutBitContext *s)
{
- while (s->bit_left < 32) {
+ while (s->bit_left < BUF_BITS) {
av_assert0(s->buf_ptr < s->buf_end);
*s->buf_ptr++ = s->bit_buf;
s->bit_buf >>= 8;
s->bit_left += 8;
}
- s->bit_left = 32;
+ s->bit_left = BUF_BITS;
s->bit_buf = 0;
}
@@ -161,29 +167,29 @@ void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
* Write up to 31 bits into a bitstream.
* Use put_bits32 to write 32 bits.
*/
-static inline void put_bits(PutBitContext *s, int n, unsigned int value)
+static inline void put_bits(PutBitContext *s, int n, BitBuf value)
{
- unsigned int bit_buf;
+ BitBuf bit_buf;
int bit_left;
- av_assert2(n <= 31 && value < (1U << n));
+ av_assert2(n <= 31 && value < (1UL << n));
bit_buf = s->bit_buf;
bit_left = s->bit_left;
/* XXX: optimize */
#ifdef BITSTREAM_WRITER_LE
- bit_buf |= value << (32 - bit_left);
+ bit_buf |= value << (BUF_BITS - bit_left);
if (n >= bit_left) {
- if (3 < s->buf_end - s->buf_ptr) {
- AV_WL32(s->buf_ptr, bit_buf);
- s->buf_ptr += 4;
+ if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {
+ AV_WLBUF(s->buf_ptr, bit_buf);
+ s->buf_ptr += sizeof(BitBuf);
} 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;
+ bit_left += BUF_BITS;
}
bit_left -= n;
#else
@@ -193,14 +199,14 @@ static inline void put_bits(PutBitContext *s, int n, unsigned int value)
} else {
bit_buf <<= bit_left;
bit_buf |= value >> (n - bit_left);
- if (3 < s->buf_end - s->buf_ptr) {
- AV_WB32(s->buf_ptr, bit_buf);
- s->buf_ptr += 4;
+ if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {
+ AV_WBBUF(s->buf_ptr, bit_buf);
+ s->buf_ptr += sizeof(BitBuf);
} else {
av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
av_assert2(0);
}
- bit_left += 32 - n;
+ bit_left += BUF_BITS - n;
bit_buf = value;
}
#endif
@@ -209,27 +215,27 @@ static inline void put_bits(PutBitContext *s, int n, unsigned int value)
s->bit_left = bit_left;
}
-static inline void put_bits_le(PutBitContext *s, int n, unsigned int value)
+static inline void put_bits_le(PutBitContext *s, int n, BitBuf value)
{
- unsigned int bit_buf;
+ BitBuf bit_buf;
int bit_left;
- av_assert2(n <= 31 && value < (1U << n));
+ av_assert2(n <= 31 && value < (1UL << n));
bit_buf = s->bit_buf;
bit_left = s->bit_left;
- bit_buf |= value << (32 - bit_left);
+ bit_buf |= value << (BUF_BITS - bit_left);
if (n >= bit_left) {
- if (3 < s->buf_end - s->buf_ptr) {
- AV_WL32(s->buf_ptr, bit_buf);
- s->buf_ptr += 4;
+ if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {
+ AV_WLBUF(s->buf_ptr, bit_buf);
+ s->buf_ptr += sizeof(BitBuf);
} 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;
+ bit_left += BUF_BITS;
}
bit_left -= n;
@@ -249,17 +255,17 @@ static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
*/
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
{
- unsigned int bit_buf;
+ BitBuf bit_buf;
int bit_left;
bit_buf = s->bit_buf;
bit_left = s->bit_left;
#ifdef BITSTREAM_WRITER_LE
- 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;
+ bit_buf |= (BitBuf)value << (BUF_BITS - bit_left);
+ if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {
+ AV_WLBUF(s->buf_ptr, bit_buf);
+ s->buf_ptr += sizeof(BitBuf);
} else {
av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
av_assert2(0);
@@ -267,10 +273,10 @@ static void av_unused put_bits32(PutBitContext *s, uint32_t value)
bit_buf = (uint64_t)value >> bit_left;
#else
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;
+ bit_buf |= (BitBuf)value >> (BUF_BITS - bit_left);
+ if (s->buf_end - s->buf_ptr >= sizeof(BitBuf)) {
+ AV_WBBUF(s->buf_ptr, bit_buf);
+ s->buf_ptr += sizeof(BitBuf);
} else {
av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
av_assert2(0);
@@ -333,7 +339,7 @@ static inline uint8_t *put_bits_ptr(PutBitContext *s)
static inline void skip_put_bytes(PutBitContext *s, int n)
{
av_assert2((put_bits_count(s) & 7) == 0);
- av_assert2(s->bit_left == 32);
+ av_assert2(s->bit_left == BUF_BITS);
av_assert0(n <= s->buf_end - s->buf_ptr);
s->buf_ptr += n;
}
@@ -346,8 +352,8 @@ static inline void skip_put_bytes(PutBitContext *s, int n)
static inline void skip_put_bits(PutBitContext *s, int n)
{
s->bit_left -= n;
- s->buf_ptr -= 4 * (s->bit_left >> 5);
- s->bit_left &= 31;
+ s->buf_ptr -= sizeof(BitBuf) * ((unsigned)s->bit_left / BUF_BITS);
+ s->bit_left &= (BUF_BITS - 1);
}
/**
@@ -357,9 +363,12 @@ static inline void skip_put_bits(PutBitContext *s, int n)
*/
static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
{
- av_assert0(size <= INT_MAX/8 - 32);
+ av_assert0(size <= INT_MAX/8 - BUF_BITS);
s->buf_end = s->buf + size;
s->size_in_bits = 8*size;
}
+#undef AV_WBBUF
+#undef AV_WLBUF
+
#endif /* AVCODEC_PUT_BITS_H */
--
2.20.1
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