Remove LAST_SKIP_BITS.

[paraslash.git] / bitstream.h

diff --git a/bitstream.h b/bitstream.h
index f8f1b49ba16fbea06d9d89f53f8d9222783a393e..f54ae62bc6b132c26c15312e117e69508557bb6c 100644 (file)
--- a/bitstream.h
+++ b/bitstream.h
@@ -14,18 +14,16 @@
                      (((const uint8_t*)(x))[2] <<  8) | \
                       ((const uint8_t*)(x))[3])
 
-# 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
@@ -79,9 +77,6 @@ struct vlc {
                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)
@@ -100,29 +95,17 @@ 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.
- */
-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);
-       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)
+       SKIP_COUNTER(re, s, n)
        CLOSE_READER(re, s)
 }
 
@@ -148,7 +131,7 @@ static inline unsigned int get_bits1(struct getbit_context *s)
  * \param bit_size The size of the buffer in bits.
  */
 static inline void init_get_bits(struct getbit_context *s,
-               const uint8_t * buffer, int bit_size)
+               const uint8_t *buffer, int bit_size)
 {
        int buffer_size = (bit_size + 7) >> 3;
        if (buffer_size < 0 || bit_size < 0) {
@@ -156,7 +139,6 @@ static inline void init_get_bits(struct getbit_context *s,
                buffer = NULL;
        }
        s->buffer = buffer;
-       s->size_in_bits = bit_size;
        s->buffer_end = buffer + buffer_size;
        s->index = 0;
 }
@@ -167,38 +149,41 @@ void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
 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_BITS(re, gb, n)
+       CLOSE_READER(re, gb)
+       return code;
 }