X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=bitstream.h;h=98937e89f2b98f126007d795f8070c0b33508598;hp=5875b0d090e6e8007d34766ee090950c819188dd;hb=04c16387cc13317ded03ce478b131d94558f585f;hpb=3fd8d0567ae654aed7e97e832568d3e1b98e20a2

diff --git a/bitstream.h b/bitstream.h
index 5875b0d0..98937e89 100644
--- a/bitstream.h
+++ b/bitstream.h
@@ -3,8 +3,7 @@
  *
  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
  *
- * Licensed under the GNU Lesser General Public License.
- * For licencing details see COPYING.LIB.
+ * Licensed under the GNU Lesser General Public License, see file COPYING.LIB.
  */
 
 /** \file bitstream.h Bitstream structures and inline functions. */
@@ -13,20 +12,18 @@
 struct getbit_context {
 	/** Start of the internal buffer. */
 	const uint8_t *buffer;
-	/** End of the internal buffer. */
-	const uint8_t *buffer_end;
+	/** Length of buffer in bits (always a multiple of 8). */
+	uint32_t num_bits;
 	/** Bit counter. */
 	int index;
 };
 
-#define VLC_TYPE int16_t
-
 /** A variable length code table. */
 struct vlc {
 	/** Number of bits of the table. */
 	int bits;
 	/** The code and the bits table. */
-	VLC_TYPE(*table)[2];
+	int16_t (*table)[2];
 	/** The size of the table. */
 	int table_size;
 	/** Amount of memory allocated so far. */
@@ -36,8 +33,12 @@ struct vlc {
 static inline uint32_t show_bits(struct getbit_context *gbc, int num)
 {
 	int idx = gbc->index;
-	const uint8_t *p = gbc->buffer + (idx >> 3);
-	uint32_t x = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
+	const char *p;
+	uint32_t x;
+
+	assert(idx + num <= gbc->num_bits);
+	p = (const char *)gbc->buffer + (idx >> 3);
+	x = read_u32_be(p);
 	return (x << (idx & 7)) >> (32 - num);
 }
 
@@ -48,12 +49,13 @@ static inline int get_bits_count(struct getbit_context *gbc)
 
 static inline void skip_bits(struct getbit_context *gbc, int n)
 {
+	assert(gbc->index + n <= gbc->num_bits);
 	gbc->index += n;
 }
 
 static inline unsigned int get_bits(struct getbit_context *gbc, int n)
 {
-	unsigned int ret = show_bits(gbc, n);
+	unsigned int ret = show_bits(gbc, n); /* checks n */
 	skip_bits(gbc, n);
 	return ret;
 }
@@ -61,8 +63,13 @@ static inline unsigned int get_bits(struct getbit_context *gbc, int n)
 /* This is rather hot, we can do better than get_bits(gbc, 1). */
 static inline unsigned int get_bit(struct getbit_context *gbc)
 {
-	int idx = gbc->index++;
-	uint8_t tmp = gbc->buffer[idx >> 3], mask = 1 << (7 - (idx & 7));
+	int idx;
+	uint8_t tmp, mask;
+
+	assert(gbc->index < gbc->num_bits);
+	idx = gbc->index++;
+	tmp = gbc->buffer[idx >> 3];
+	mask = 1 << (7 - (idx & 7));
 	return !!(tmp & mask);
 }
 
@@ -81,11 +88,11 @@ static inline void init_get_bits(struct getbit_context *gbc,
 		const uint8_t *buffer, int size)
 {
 	gbc->buffer = buffer;
-	gbc->buffer_end = buffer + size;
+	gbc->num_bits = size * 8;
 	gbc->index = 0;
 }
 
 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);
-int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2], int bits);
+int get_vlc(struct getbit_context *gbc, const struct vlc *vlc);