X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=bitstream.h;h=553dd04a0737b0c0cac9c845be8a460a13a64ffd;hp=0a701d7c8636229f98b37f49dd16603a8b132a1b;hb=1301313c2eb8a9ce0ba8ce22062d1f87fc419aa2;hpb=226ce82aaccff7e74a6fadd028743b731a3744d2

diff --git a/bitstream.h b/bitstream.h
index 0a701d7c..553dd04a 100644
--- a/bitstream.h
+++ b/bitstream.h
@@ -14,19 +14,16 @@
                      (((const uint8_t*)(x))[2] <<  8) | \
                       ((const uint8_t*)(x))[3])
 
-# define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
-# define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
+#define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
 
-/**
- * Structure for bistream I/O.
- *
- * The buffer, buffer_end and size_in_bits fields must be present and are used
- * by every reader.
- */
+/** Structure for bistream I/O. */
 struct getbit_context {
-	const uint8_t *buffer, *buffer_end;
+	/* Start of the internal buffer. */
+	const uint8_t *buffer;
+	/* End of the internal buffer. */
+	const uint8_t *buffer_end;
+	/** Bit counter. */
 	int index;
-	int size_in_bits;
 };
 
 #define VLC_TYPE int16_t
@@ -37,8 +34,6 @@ struct vlc {
 	int table_size, table_allocated;
 };
 
-#define MIN_CACHE_BITS 25
-
 /** Load \a gb into local variables. */
 #define OPEN_READER(name, gb)\
 	int name##_index= (gb)->index;\
@@ -50,11 +45,9 @@ struct vlc {
 
 /**
  * Refill the internal cache from the bitstream.
- *
- * After this call at least MIN_CACHE_BITS will be available.
  */
 #define UPDATE_CACHE(name, gb)\
-	name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer) \
+	name##_cache= AV_RB32( ((gb)->buffer) \
 		+ (name##_index >> 3) ) << (name##_index & 0x07);\
 
 /**
@@ -68,25 +61,11 @@ struct vlc {
 /**
  * Increment the internal bit counter.
  *
- * \sa SKIP_CACHE, SKIP_BITS.
+ * \sa SKIP_CACHE.
  */
 #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)\
-	}\
-
-/** This is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER. */
-#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
-
 /** Return the next num bits. */
 #define SHOW_UBITS(name, gb, num)\
 	NEG_USR32(name##_cache, num)
@@ -96,14 +75,8 @@ static inline int get_bits_count(struct getbit_context *s)
 	return s->index;
 }
 
-static inline void skip_bits_long(struct getbit_context *s, int n)
-{
-	s->index += n;
-}
-
 /**
- * reads 1-17 bits.
- * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
+ * Read 1-17 bits.
  */
 static inline unsigned int get_bits(struct getbit_context *s, int n)
 {
@@ -111,34 +84,14 @@ static inline unsigned int get_bits(struct getbit_context *s, int n)
 	OPEN_READER(re, s)
 	UPDATE_CACHE(re, s)
 	tmp = SHOW_UBITS(re, s, n);
-	LAST_SKIP_BITS(re, s, n)
+	SKIP_COUNTER(re, s, n)
 	CLOSE_READER(re, s)
 	return tmp;
 }
 
-/**
- * Show 1-17 bits.
- *
- * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2
- * reader can't.
- */
-static inline unsigned int show_bits(struct getbit_context *s, int n)
-{
-	register int tmp;
-	OPEN_READER(re, s)
-	UPDATE_CACHE(re, s)
-	tmp = SHOW_UBITS(re, s, n);
-//    CLOSE_READER(re, s)
-	return tmp;
-}
-
 static inline void skip_bits(struct getbit_context *s, int n)
 {
-	/* gcc seems to optimize this to s->index+=n for the ALT_READER :)) */
-	OPEN_READER(re, s)
-	UPDATE_CACHE(re, s)
-	LAST_SKIP_BITS(re, s, n)
-	CLOSE_READER(re, s)
+	s->index += n;
 }
 
 static inline unsigned int get_bits1(struct getbit_context *s)
@@ -153,19 +106,6 @@ static inline unsigned int get_bits1(struct getbit_context *s)
 	return result;
 }
 
-/**
- * reads 0-32 bits.
- */
-static inline unsigned int get_bits_long(struct getbit_context *s, int n)
-{
-	if (n <= 17)
-		return get_bits(s, n);
-	else {
-		int ret = get_bits(s, 16) << (n - 16);
-		return ret | get_bits(s, n - 16);
-	}
-}
-
 /**
  * Initialize a getbit_context structure.
  *
@@ -173,61 +113,58 @@ static inline unsigned int get_bits_long(struct getbit_context *s, int n)
  * bytes larger then the actual read bits * because some optimized bitstream
  * readers read 32 or 64 bit at once and could read over the end.
  *
- * \param bit_size The size of the buffer in bits.
+ * \param bit_size The size of the buffer in bytes.
  */
 static inline void init_get_bits(struct getbit_context *s,
-		const uint8_t * buffer, int bit_size)
+		const uint8_t *buffer, int size)
 {
-	int buffer_size = (bit_size + 7) >> 3;
-	if (buffer_size < 0 || bit_size < 0) {
-		buffer_size = bit_size = 0;
-		buffer = NULL;
-	}
 	s->buffer = buffer;
-	s->size_in_bits = bit_size;
-	s->buffer_end = buffer + buffer_size;
+	s->buffer_end = buffer + size;
 	s->index = 0;
 }
 
-int init_vlc(struct vlc *vlc, int nb_bits, int nb_codes,
-	const void *bits, int bits_wrap, int bits_size,
-	const void *codes, int codes_wrap, int codes_size);
+void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
+		const void *codes, int codes_size);
 
 void free_vlc(struct vlc *vlc);
 
 /**
+ * Parse a vlc code.
+ *
+ * \param bits The number of bits which will be read at once, must be
+ * identical to nb_bits in init_vlc()
  *
- * if the vlc code is invalid and max_depth=1 than no bits will be removed
- * if the vlc code is invalid and max_depth>1 than the number of bits removed
- * is undefined
+ * \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.
  */
-#define GET_VLC(code, name, gb, table, bits, max_depth)\
-{\
-    int n, index, nb_bits;\
-\
-    index= SHOW_UBITS(name, gb, bits);\
-    code = table[index][0];\
-    n    = table[index][1];\
-\
-    if(max_depth > 1 && n < 0){\
-        LAST_SKIP_BITS(name, gb, bits)\
-        UPDATE_CACHE(name, gb)\
-\
-        nb_bits = -n;\
-\
-        index= SHOW_UBITS(name, gb, nb_bits) + code;\
-        code = table[index][0];\
-        n    = table[index][1];\
-        if(max_depth > 2 && n < 0){\
-            LAST_SKIP_BITS(name, gb, nb_bits)\
-            UPDATE_CACHE(name, gb)\
-\
-            nb_bits = -n;\
-\
-            index= SHOW_UBITS(name, gb, nb_bits) + code;\
-            code = table[index][0];\
-            n    = table[index][1];\
-        }\
-    }\
-    SKIP_BITS(name, gb, n)\
+static inline int get_vlc(struct getbit_context *gb, 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);
+	code = table[idx][0];
+	n = table[idx][1];
+	if (max_depth > 1 && n < 0) {
+		SKIP_COUNTER(re, gb, bits)
+		UPDATE_CACHE(re, gb)
+		nb_bits = -n;
+		idx = SHOW_UBITS(re, gb, 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)
+			nb_bits = -n;
+			idx = SHOW_UBITS(re, gb, nb_bits) + code;
+			code = table[idx][0];
+			n = table[idx][1];
+		}
+	}
+	SKIP_CACHE(re, gb, n)
+	SKIP_COUNTER(re, gb, n)
+	CLOSE_READER(re, gb)
+	return code;
 }