X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=bitstream.h;h=d13ef4c2bd6946deff17e9104432052b1319b25e;hp=d052337c1a1825d29bc700c8a918177220dc4f74;hb=4163d3460d5dc61264636ebeb7b3fe8052b93568;hpb=ae9a1e8863223938de42debb38a20b2060e0c181

diff --git a/bitstream.h b/bitstream.h
index d052337c..d13ef4c2 100644
--- a/bitstream.h
+++ b/bitstream.h
@@ -14,8 +14,6 @@
                      (((const uint8_t*)(x))[2] <<  8) | \
                       ((const uint8_t*)(x))[3])
 
-#define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
-
 /** Structure for bistream I/O. */
 struct getbit_context {
 	/* Start of the internal buffer. */
@@ -34,91 +32,36 @@ struct vlc {
 	int table_size, table_allocated;
 };
 
-/** Load \a gb into local variables. */
-#define OPEN_READER(name, gb)\
-	int name##_index= (gb)->index;\
-	int name##_cache= 0;\
-
-/** Store local vars in gb. */
-#define CLOSE_READER(name, gb)\
-	(gb)->index= name##_index;\
-
-/**
- * Refill the internal cache from the bitstream.
- */
-#define UPDATE_CACHE(name, gb)\
-	name##_cache= AV_RB32( ((gb)->buffer) \
-		+ (name##_index >> 3) ) << (name##_index & 0x07);\
-
-/**
- * Remove the next num bits from the cache.
- *
- * SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER).
- */
-#define SKIP_CACHE(name, gb, num)\
-	name##_cache <<= (num);
-
-/**
- * Increment the internal bit counter.
- *
- * \sa SKIP_CACHE, SKIP_BITS.
- */
-#define SKIP_COUNTER(name, gb, num)\
-	name##_index += (num);\
-
-/**
- * Skip over the next num bits.
- *
- * This is equivalent to SKIP_CACHE; SKIP_COUNTER.
- */
-#define SKIP_BITS(name, gb, num)\
-	{\
-		SKIP_CACHE(name, gb, num)\
-		SKIP_COUNTER(name, gb, num)\
-	}\
-
-/** Return the next num bits. */
-#define SHOW_UBITS(name, gb, num)\
-	NEG_USR32(name##_cache, num)
-
-static inline int get_bits_count(struct getbit_context *s)
+static inline uint32_t show_bits(struct getbit_context *gbc, int num)
 {
-	return s->index;
+	int idx = gbc->index;
+	uint32_t x = AV_RB32(gbc->buffer + (idx >> 3)) << (idx & 7);
+	return x >> (32 - num);
 }
 
-/**
- * Read 1-17 bits.
- */
-static inline unsigned int get_bits(struct getbit_context *s, int n)
+static inline int get_bits_count(struct getbit_context *gbc)
 {
-	register int tmp;
-	OPEN_READER(re, s)
-	UPDATE_CACHE(re, s)
-	tmp = SHOW_UBITS(re, s, n);
-	SKIP_COUNTER(re, s, n)
-	CLOSE_READER(re, s)
-	return tmp;
+	return gbc->index;
 }
 
-static inline void skip_bits(struct getbit_context *s, int n)
+static inline void skip_bits(struct getbit_context *gbc, int n)
 {
-	/* gcc seems to optimize this to s->index+=n for the ALT_READER :)) */
-	OPEN_READER(re, s)
-	UPDATE_CACHE(re, s)
-	SKIP_COUNTER(re, s, n)
-	CLOSE_READER(re, s)
+	gbc->index += n;
 }
 
-static inline unsigned int get_bits1(struct getbit_context *s)
+static inline unsigned int get_bits(struct getbit_context *gbc, int n)
 {
-	int idx = s->index;
-	uint8_t result = s->buffer[idx >> 3];
+	unsigned int ret = show_bits(gbc, n);
+	skip_bits(gbc, n);
+	return ret;
+}
 
-	result <<= (idx & 0x07);
-	result >>= 8 - 1;
-	idx++;
-	s->index = idx;
-	return result;
+/* This is rather hot, we can do better than get_bits(gbc, 1). */
+static inline unsigned int get_bits1(struct getbit_context *gbc)
+{
+	int idx = gbc->index++;
+	uint8_t tmp = gbc->buffer[idx >> 3], mask = (1 << (7 - (idx & 7)));
+	return !!(tmp & mask);
 }
 
 /**
@@ -130,12 +73,12 @@ static inline unsigned int get_bits1(struct getbit_context *s)
  *
  * \param bit_size The size of the buffer in bytes.
  */
-static inline void init_get_bits(struct getbit_context *s,
+static inline void init_get_bits(struct getbit_context *gbc,
 		const uint8_t *buffer, int size)
 {
-	s->buffer = buffer;
-	s->buffer_end = buffer + size;
-	s->index = 0;
+	gbc->buffer = buffer;
+	gbc->buffer_end = buffer + size;
+	gbc->index = 0;
 }
 
 void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
@@ -152,33 +95,28 @@ void free_vlc(struct vlc *vlc);
  * \param max_depth The number of times bits bits must be read to completely
  * read the longest vlc code = (max_vlc_length + bits - 1) / bits.
  */
-static inline int get_vlc(struct getbit_context *gb, VLC_TYPE(*table)[2],
+static inline int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2],
 		int bits, int max_depth)
 {
 	int n, idx, nb_bits, code;
 
-	OPEN_READER(re, gb)
-	UPDATE_CACHE(re, gb)
-	idx = SHOW_UBITS(re, gb, bits);
+	idx = show_bits(gbc, bits);
 	code = table[idx][0];
 	n = table[idx][1];
 	if (max_depth > 1 && n < 0) {
-		SKIP_COUNTER(re, gb, bits)
-		UPDATE_CACHE(re, gb)
+		skip_bits(gbc, bits);
 		nb_bits = -n;
-		idx = SHOW_UBITS(re, gb, nb_bits) + code;
+		idx = show_bits(gbc, nb_bits) + code;
 		code = table[idx][0];
 		n = table[idx][1];
 		if (max_depth > 2 && n < 0) {
-			SKIP_COUNTER(re, gb, nb_bits)
-			UPDATE_CACHE(re, gb)
+			skip_bits(gbc, nb_bits);
 			nb_bits = -n;
-			idx = SHOW_UBITS(re, gb, nb_bits) + code;
+			idx = show_bits(gbc, nb_bits) + code;
 			code = table[idx][0];
 			n = table[idx][1];
 		}
 	}
-	SKIP_BITS(re, gb, n)
-	CLOSE_READER(re, gb)
+	skip_bits(gbc, n);
 	return code;
 }