1 /* GStreamer
2 *
3 * Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
19 */
21 #ifndef __GST_BIT_READER_H__
22 #define __GST_BIT_READER_H__
24 #include <gst/gst.h>
26 /* FIXME: inline functions */
28 G_BEGIN_DECLS
30 #define GST_BIT_READER(reader) ((GstBitReader *) (reader))
32 /**
33 * GstBitReader:
34 * @data: Data from which the bit reader will read
35 * @size: Size of @data in bytes
36 * @byte: Current byte position
37 * @bit: Bit position in the current byte
38 *
39 * A bit reader instance.
40 */
41 typedef struct {
42 const guint8 *data;
43 guint size;
45 guint byte; /* Byte position */
46 guint bit; /* Bit position in the current byte */
47 } GstBitReader;
49 GstBitReader * gst_bit_reader_new (const guint8 *data, guint size) G_GNUC_MALLOC;
50 GstBitReader * gst_bit_reader_new_from_buffer (const GstBuffer *buffer) G_GNUC_MALLOC;
51 void gst_bit_reader_free (GstBitReader *reader);
53 void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
54 void gst_bit_reader_init_from_buffer (GstBitReader *reader, const GstBuffer *buffer);
56 gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
58 guint gst_bit_reader_get_pos (const GstBitReader *reader);
59 guint gst_bit_reader_get_remaining (const GstBitReader *reader);
61 guint gst_bit_reader_get_size (const GstBitReader *reader);
63 gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
64 gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
66 gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
67 gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
68 gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
69 gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
71 gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
72 gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
73 gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
74 gboolean gst_bit_reader_peek_bits_uint64 (const GstBitReader *reader, guint64 *val, guint nbits);
76 /**
77 * GST_BIT_READER_INIT:
78 * @data: Data from which the #GstBitReader should read
79 * @size: Size of @data in bytes
80 *
81 * A #GstBitReader must be initialized with this macro, before it can be
82 * used. This macro can used be to initialize a variable, but it cannot
83 * be assigned to a variable. In that case you have to use
84 * gst_bit_reader_init().
85 *
86 * Since: 0.10.22
87 */
88 #define GST_BIT_READER_INIT(data, size) {data, size, 0, 0}
90 /**
91 * GST_BIT_READER_INIT_FROM_BUFFER:
92 * @buffer: Buffer from which the #GstBitReader should read
93 *
94 * A #GstBitReader must be initialized with this macro, before it can be
95 * used. This macro can used be to initialize a variable, but it cannot
96 * be assigned to a variable. In that case you have to use
97 * gst_bit_reader_init().
98 *
99 * Since: 0.10.22
100 */
101 #define GST_BIT_READER_INIT_FROM_BUFFER(buffer) {GST_BUFFER_DATA (buffer), GST_BUFFER_SIZE (buffer), 0, 0}
103 /* Unchecked variants */
105 static inline void
106 gst_bit_reader_skip_unchecked (GstBitReader * reader, guint nbits)
107 {
108 reader->bit += nbits;
109 reader->byte += reader->bit / 8;
110 reader->bit = reader->bit % 8;
111 }
113 static inline void
114 gst_bit_reader_skip_to_byte_unchecked (GstBitReader * reader)
115 {
116 if (reader->bit) {
117 reader->bit = 0;
118 reader->byte++;
119 }
120 }
122 #define __GST_BIT_READER_READ_BITS_UNCHECKED(bits) \
123 static inline guint##bits \
124 gst_bit_reader_peek_bits_uint##bits##_unchecked (const GstBitReader *reader, guint nbits) \
125 { \
126 guint##bits ret = 0; \
127 const guint8 *data; \
128 guint byte, bit; \
129 \
130 data = reader->data; \
131 byte = reader->byte; \
132 bit = reader->bit; \
133 \
134 while (nbits > 0) { \
135 guint toread = MIN (nbits, 8 - bit); \
136 \
137 ret <<= toread; \
138 ret |= (data[byte] & (0xff >> bit)) >> (8 - toread - bit); \
139 \
140 bit += toread; \
141 if (bit >= 8) { \
142 byte++; \
143 bit = 0; \
144 } \
145 nbits -= toread; \
146 } \
147 \
148 return ret; \
149 } \
150 \
151 static inline guint##bits \
152 gst_bit_reader_get_bits_uint##bits##_unchecked (GstBitReader *reader, guint nbits) \
153 { \
154 guint##bits ret; \
155 \
156 ret = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
157 \
158 gst_bit_reader_skip_unchecked (reader, nbits); \
159 \
160 return ret; \
161 }
163 __GST_BIT_READER_READ_BITS_UNCHECKED (8)
164 __GST_BIT_READER_READ_BITS_UNCHECKED (16)
165 __GST_BIT_READER_READ_BITS_UNCHECKED (32)
166 __GST_BIT_READER_READ_BITS_UNCHECKED (64)
168 #undef __GST_BIT_READER_READ_BITS_UNCHECKED
170 /* unchecked variants -- do not use */
172 static inline guint
173 _gst_bit_reader_get_size_unchecked (const GstBitReader * reader)
174 {
175 return reader->size * 8;
176 }
178 static inline guint
179 _gst_bit_reader_get_pos_unchecked (const GstBitReader * reader)
180 {
181 return reader->byte * 8 + reader->bit;
182 }
184 static inline guint
185 _gst_bit_reader_get_remaining_unchecked (const GstBitReader * reader)
186 {
187 return reader->size * 8 - (reader->byte * 8 + reader->bit);
188 }
190 /* inlined variants -- do not use directly */
191 static inline guint
192 _gst_bit_reader_get_size_inline (const GstBitReader * reader)
193 {
194 g_return_val_if_fail (reader != NULL, 0);
196 return _gst_bit_reader_get_size_unchecked (reader);
197 }
199 static inline guint
200 _gst_bit_reader_get_pos_inline (const GstBitReader * reader)
201 {
202 g_return_val_if_fail (reader != NULL, 0);
204 return _gst_bit_reader_get_pos_unchecked (reader);
205 }
207 static inline guint
208 _gst_bit_reader_get_remaining_inline (const GstBitReader * reader)
209 {
210 g_return_val_if_fail (reader != NULL, 0);
212 return _gst_bit_reader_get_remaining_unchecked (reader);
213 }
215 static inline gboolean
216 _gst_bit_reader_skip_inline (GstBitReader * reader, guint nbits)
217 {
218 g_return_val_if_fail (reader != NULL, FALSE);
220 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits)
221 return FALSE;
223 gst_bit_reader_skip_unchecked (reader, nbits);
225 return TRUE;
226 }
228 static inline gboolean
229 _gst_bit_reader_skip_to_byte_inline (GstBitReader * reader)
230 {
231 g_return_val_if_fail (reader != NULL, FALSE);
233 if (reader->byte > reader->size)
234 return FALSE;
236 gst_bit_reader_skip_to_byte_unchecked (reader);
238 return TRUE;
239 }
241 #define __GST_BIT_READER_READ_BITS_INLINE(bits) \
242 static inline gboolean \
243 _gst_bit_reader_get_bits_uint##bits##_inline (GstBitReader *reader, guint##bits *val, guint nbits) \
244 { \
245 g_return_val_if_fail (reader != NULL, FALSE); \
246 g_return_val_if_fail (val != NULL, FALSE); \
247 g_return_val_if_fail (nbits <= bits, FALSE); \
248 \
249 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
250 return FALSE; \
251 \
252 *val = gst_bit_reader_get_bits_uint##bits##_unchecked (reader, nbits); \
253 return TRUE; \
254 } \
255 \
256 static inline gboolean \
257 _gst_bit_reader_peek_bits_uint##bits##_inline (const GstBitReader *reader, guint##bits *val, guint nbits) \
258 { \
259 g_return_val_if_fail (reader != NULL, FALSE); \
260 g_return_val_if_fail (val != NULL, FALSE); \
261 g_return_val_if_fail (nbits <= bits, FALSE); \
262 \
263 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
264 return FALSE; \
265 \
266 *val = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
267 return TRUE; \
268 }
270 __GST_BIT_READER_READ_BITS_INLINE (8)
271 __GST_BIT_READER_READ_BITS_INLINE (16)
272 __GST_BIT_READER_READ_BITS_INLINE (32)
273 __GST_BIT_READER_READ_BITS_INLINE (64)
275 #undef __GST_BIT_READER_READ_BITS_INLINE
277 #ifndef GST_BIT_READER_DISABLE_INLINES
279 #define gst_bit_reader_get_size(reader) \
280 _gst_bit_reader_get_size_inline (reader)
281 #define gst_bit_reader_get_pos(reader) \
282 _gst_bit_reader_get_pos_inline (reader)
283 #define gst_bit_reader_get_remaining(reader) \
284 _gst_bit_reader_get_remaining_inline (reader)
286 /* we use defines here so we can add the G_LIKELY() */
288 #define gst_bit_reader_skip(reader, nbits)\
289 G_LIKELY (_gst_bit_reader_skip_inline(reader, nbits))
290 #define gst_bit_reader_skip_to_byte(reader)\
291 G_LIKELY (_gst_bit_reader_skip_to_byte_inline(reader))
293 #define gst_bit_reader_get_bits_uint8(reader, val, nbits) \
294 G_LIKELY (_gst_bit_reader_get_bits_uint8_inline (reader, val, nbits))
295 #define gst_bit_reader_get_bits_uint16(reader, val, nbits) \
296 G_LIKELY (_gst_bit_reader_get_bits_uint16_inline (reader, val, nbits))
297 #define gst_bit_reader_get_bits_uint32(reader, val, nbits) \
298 G_LIKELY (_gst_bit_reader_get_bits_uint32_inline (reader, val, nbits))
299 #define gst_bit_reader_get_bits_uint64(reader, val, nbits) \
300 G_LIKELY (_gst_bit_reader_get_bits_uint64_inline (reader, val, nbits))
302 #define gst_bit_reader_peek_bits_uint8(reader, val, nbits) \
303 G_LIKELY (_gst_bit_reader_peek_bits_uint8_inline (reader, val, nbits))
304 #define gst_bit_reader_peek_bits_uint16(reader, val, nbits) \
305 G_LIKELY (_gst_bit_reader_peek_bits_uint16_inline (reader, val, nbits))
306 #define gst_bit_reader_peek_bits_uint32(reader, val, nbits) \
307 G_LIKELY (_gst_bit_reader_peek_bits_uint32_inline (reader, val, nbits))
308 #define gst_bit_reader_peek_bits_uint64(reader, val, nbits) \
309 G_LIKELY (_gst_bit_reader_peek_bits_uint64_inline (reader, val, nbits))
310 #endif
312 G_END_DECLS
314 #endif /* __GST_BIT_READER_H__ */