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., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 */
20
21 #ifndef __GST_BIT_READER_H__
22 #define __GST_BIT_READER_H__
23
24 #include <gst/gst.h>
25 #include <gst/base/base-prelude.h>
26
27 /* FIXME: inline functions */
28
29 G_BEGIN_DECLS
30
31 #define GST_BIT_READER(reader) ((GstBitReader *) (reader))
32
33 /**
34 * GstBitReader:
35 * @data: (array length=size): Data from which the bit reader will
36 * read
37 * @size: Size of @data in bytes
38 * @byte: Current byte position
39 * @bit: Bit position in the current byte
40 *
41 * A bit reader instance.
42 */
43 typedef struct {
44 const guint8 *data;
45 guint size;
46
47 guint byte; /* Byte position */
48 guint bit; /* Bit position in the current byte */
49
50 /* < private > */
51 gpointer _gst_reserved[GST_PADDING];
52 } GstBitReader;
53
54 GST_BASE_API
55 GstBitReader * gst_bit_reader_new (const guint8 *data, guint size) G_GNUC_MALLOC;
56
57 GST_BASE_API
58 void gst_bit_reader_free (GstBitReader *reader);
59
60 GST_BASE_API
61 void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
62
63 GST_BASE_API
64 gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
65
66 GST_BASE_API
67 guint gst_bit_reader_get_pos (const GstBitReader *reader);
68
69 GST_BASE_API
70 guint gst_bit_reader_get_remaining (const GstBitReader *reader);
71
72 GST_BASE_API
73 guint gst_bit_reader_get_size (const GstBitReader *reader);
74
75 GST_BASE_API
76 gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
77
78 GST_BASE_API
79 gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
80
81 GST_BASE_API
82 gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
83
84 GST_BASE_API
85 gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
86
87 GST_BASE_API
88 gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
89
90 GST_BASE_API
91 gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
92
93 GST_BASE_API
94 gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
95
96 GST_BASE_API
97 gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
98
99 GST_BASE_API
100 gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
101
102 GST_BASE_API
103 gboolean gst_bit_reader_peek_bits_uint64 (const GstBitReader *reader, guint64 *val, guint nbits);
104
105 /**
106 * GST_BIT_READER_INIT:
107 * @data: Data from which the #GstBitReader should read
108 * @size: Size of @data in bytes
109 *
110 * A #GstBitReader must be initialized with this macro, before it can be
111 * used. This macro can used be to initialize a variable, but it cannot
112 * be assigned to a variable. In that case you have to use
113 * gst_bit_reader_init().
114 */
115 #define GST_BIT_READER_INIT(data, size) {data, size, 0, 0}
116
117 /* Unchecked variants */
118
119 static inline void
gst_bit_reader_skip_unchecked(GstBitReader * reader,guint nbits)120 gst_bit_reader_skip_unchecked (GstBitReader * reader, guint nbits)
121 {
122 reader->bit += nbits;
123 reader->byte += reader->bit / 8;
124 reader->bit = reader->bit % 8;
125 }
126
127 static inline void
gst_bit_reader_skip_to_byte_unchecked(GstBitReader * reader)128 gst_bit_reader_skip_to_byte_unchecked (GstBitReader * reader)
129 {
130 if (reader->bit) {
131 reader->bit = 0;
132 reader->byte++;
133 }
134 }
135
136 #define __GST_BIT_READER_READ_BITS_UNCHECKED(bits) \
137 static inline guint##bits \
138 gst_bit_reader_peek_bits_uint##bits##_unchecked (const GstBitReader *reader, guint nbits) \
139 { \
140 guint##bits ret = 0; \
141 const guint8 *data; \
142 guint byte, bit; \
143 \
144 data = reader->data; \
145 byte = reader->byte; \
146 bit = reader->bit; \
147 \
148 while (nbits > 0) { \
149 guint toread = MIN (nbits, 8 - bit); \
150 \
151 ret <<= toread; \
152 ret |= (data[byte] & (0xff >> bit)) >> (8 - toread - bit); \
153 \
154 bit += toread; \
155 if (bit >= 8) { \
156 byte++; \
157 bit = 0; \
158 } \
159 nbits -= toread; \
160 } \
161 \
162 return ret; \
163 } \
164 \
165 static inline guint##bits \
166 gst_bit_reader_get_bits_uint##bits##_unchecked (GstBitReader *reader, guint nbits) \
167 { \
168 guint##bits ret; \
169 \
170 ret = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
171 \
172 gst_bit_reader_skip_unchecked (reader, nbits); \
173 \
174 return ret; \
175 }
176
177 __GST_BIT_READER_READ_BITS_UNCHECKED (8)
178 __GST_BIT_READER_READ_BITS_UNCHECKED (16)
179 __GST_BIT_READER_READ_BITS_UNCHECKED (32)
180 __GST_BIT_READER_READ_BITS_UNCHECKED (64)
181
182 #undef __GST_BIT_READER_READ_BITS_UNCHECKED
183
184 /* unchecked variants -- do not use */
185
186 static inline guint
_gst_bit_reader_get_size_unchecked(const GstBitReader * reader)187 _gst_bit_reader_get_size_unchecked (const GstBitReader * reader)
188 {
189 return reader->size * 8;
190 }
191
192 static inline guint
_gst_bit_reader_get_pos_unchecked(const GstBitReader * reader)193 _gst_bit_reader_get_pos_unchecked (const GstBitReader * reader)
194 {
195 return reader->byte * 8 + reader->bit;
196 }
197
198 static inline guint
_gst_bit_reader_get_remaining_unchecked(const GstBitReader * reader)199 _gst_bit_reader_get_remaining_unchecked (const GstBitReader * reader)
200 {
201 return reader->size * 8 - (reader->byte * 8 + reader->bit);
202 }
203
204 /* inlined variants -- do not use directly */
205 static inline guint
_gst_bit_reader_get_size_inline(const GstBitReader * reader)206 _gst_bit_reader_get_size_inline (const GstBitReader * reader)
207 {
208 g_return_val_if_fail (reader != NULL, 0);
209
210 return _gst_bit_reader_get_size_unchecked (reader);
211 }
212
213 static inline guint
_gst_bit_reader_get_pos_inline(const GstBitReader * reader)214 _gst_bit_reader_get_pos_inline (const GstBitReader * reader)
215 {
216 g_return_val_if_fail (reader != NULL, 0);
217
218 return _gst_bit_reader_get_pos_unchecked (reader);
219 }
220
221 static inline guint
_gst_bit_reader_get_remaining_inline(const GstBitReader * reader)222 _gst_bit_reader_get_remaining_inline (const GstBitReader * reader)
223 {
224 g_return_val_if_fail (reader != NULL, 0);
225
226 return _gst_bit_reader_get_remaining_unchecked (reader);
227 }
228
229 static inline gboolean
_gst_bit_reader_skip_inline(GstBitReader * reader,guint nbits)230 _gst_bit_reader_skip_inline (GstBitReader * reader, guint nbits)
231 {
232 g_return_val_if_fail (reader != NULL, FALSE);
233
234 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits)
235 return FALSE;
236
237 gst_bit_reader_skip_unchecked (reader, nbits);
238
239 return TRUE;
240 }
241
242 static inline gboolean
_gst_bit_reader_skip_to_byte_inline(GstBitReader * reader)243 _gst_bit_reader_skip_to_byte_inline (GstBitReader * reader)
244 {
245 g_return_val_if_fail (reader != NULL, FALSE);
246
247 if (reader->byte > reader->size)
248 return FALSE;
249
250 gst_bit_reader_skip_to_byte_unchecked (reader);
251
252 return TRUE;
253 }
254
255 #define __GST_BIT_READER_READ_BITS_INLINE(bits) \
256 static inline gboolean \
257 _gst_bit_reader_get_bits_uint##bits##_inline (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_get_bits_uint##bits##_unchecked (reader, nbits); \
267 return TRUE; \
268 } \
269 \
270 static inline gboolean \
271 _gst_bit_reader_peek_bits_uint##bits##_inline (const GstBitReader *reader, guint##bits *val, guint nbits) \
272 { \
273 g_return_val_if_fail (reader != NULL, FALSE); \
274 g_return_val_if_fail (val != NULL, FALSE); \
275 g_return_val_if_fail (nbits <= bits, FALSE); \
276 \
277 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
278 return FALSE; \
279 \
280 *val = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
281 return TRUE; \
282 }
283
284 __GST_BIT_READER_READ_BITS_INLINE (8)
285 __GST_BIT_READER_READ_BITS_INLINE (16)
286 __GST_BIT_READER_READ_BITS_INLINE (32)
287 __GST_BIT_READER_READ_BITS_INLINE (64)
288
289 #undef __GST_BIT_READER_READ_BITS_INLINE
290
291 #ifndef GST_BIT_READER_DISABLE_INLINES
292
293 #define gst_bit_reader_get_size(reader) \
294 _gst_bit_reader_get_size_inline (reader)
295 #define gst_bit_reader_get_pos(reader) \
296 _gst_bit_reader_get_pos_inline (reader)
297 #define gst_bit_reader_get_remaining(reader) \
298 _gst_bit_reader_get_remaining_inline (reader)
299
300 /* we use defines here so we can add the G_LIKELY() */
301
302 #define gst_bit_reader_skip(reader, nbits)\
303 G_LIKELY (_gst_bit_reader_skip_inline(reader, nbits))
304 #define gst_bit_reader_skip_to_byte(reader)\
305 G_LIKELY (_gst_bit_reader_skip_to_byte_inline(reader))
306
307 #define gst_bit_reader_get_bits_uint8(reader, val, nbits) \
308 G_LIKELY (_gst_bit_reader_get_bits_uint8_inline (reader, val, nbits))
309 #define gst_bit_reader_get_bits_uint16(reader, val, nbits) \
310 G_LIKELY (_gst_bit_reader_get_bits_uint16_inline (reader, val, nbits))
311 #define gst_bit_reader_get_bits_uint32(reader, val, nbits) \
312 G_LIKELY (_gst_bit_reader_get_bits_uint32_inline (reader, val, nbits))
313 #define gst_bit_reader_get_bits_uint64(reader, val, nbits) \
314 G_LIKELY (_gst_bit_reader_get_bits_uint64_inline (reader, val, nbits))
315
316 #define gst_bit_reader_peek_bits_uint8(reader, val, nbits) \
317 G_LIKELY (_gst_bit_reader_peek_bits_uint8_inline (reader, val, nbits))
318 #define gst_bit_reader_peek_bits_uint16(reader, val, nbits) \
319 G_LIKELY (_gst_bit_reader_peek_bits_uint16_inline (reader, val, nbits))
320 #define gst_bit_reader_peek_bits_uint32(reader, val, nbits) \
321 G_LIKELY (_gst_bit_reader_peek_bits_uint32_inline (reader, val, nbits))
322 #define gst_bit_reader_peek_bits_uint64(reader, val, nbits) \
323 G_LIKELY (_gst_bit_reader_peek_bits_uint64_inline (reader, val, nbits))
324 #endif
325
326 G_END_DECLS
327
328 #endif /* __GST_BIT_READER_H__ */
329