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[FFmpeg-devel,1/2] avcodec/put_bits: Parametrize bit buffer type

Message ID 20200717194120.8803-1-steinar+ffmpeg@gunderson.no
State Accepted
Headers show
Series [FFmpeg-devel,1/2] avcodec/put_bits: Parametrize bit buffer type
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Commit Message

Steinar H. Gunderson July 17, 2020, 7:41 p.m. UTC
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(-)

Comments

Michael Niedermayer July 18, 2020, 11:34 a.m. UTC | #1
On Fri, Jul 17, 2020 at 09:41:19PM +0200, Steinar H. Gunderson wrote:
> 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(-)
[...]

> @@ -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);

this from libavcodec/mpegvideo_enc.c 
            set_put_bits_buffer_size(&s->pb, FFMIN(s->thread_context[i]->pb.buf_end - s->pb.buf, INT_MAX/8-32));
needs to be updated too

[...]
Steinar H. Gunderson July 18, 2020, 2:52 p.m. UTC | #2
On Sat, Jul 18, 2020 at 01:34:55PM +0200, Michael Niedermayer wrote:
> this from libavcodec/mpegvideo_enc.c 
>             set_put_bits_buffer_size(&s->pb, FFMIN(s->thread_context[i]->pb.buf_end - s->pb.buf, INT_MAX/8-32));
> needs to be updated too

OK. Including in v3, sending shortly.

/* Steinar */
diff mbox series

Patch

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 */