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 #ifdef HAVE_CONFIG_H
22 #include "config.h"
23 #endif
24
25 #define GST_BIT_READER_DISABLE_INLINES
26 #include "gstbitreader.h"
27
28 #include <string.h>
29
30 /**
31 * SECTION:gstbitreader
32 * @title: GstBitReader
33 * @short_description: Reads any number of bits from a memory buffer
34 * @symbols:
35 * - gst_bit_reader_skip_unchecked
36 * - gst_bit_reader_skip_to_byte_unchecked
37 * - gst_bit_reader_get_bits_uint8_unchecked
38 * - gst_bit_reader_peek_bits_uint8_unchecked
39 * - gst_bit_reader_get_bits_uint16_unchecked
40 * - gst_bit_reader_peek_bits_uint16_unchecked
41 * - gst_bit_reader_get_bits_uint32_unchecked
42 * - gst_bit_reader_peek_bits_uint32_unchecked
43 * - gst_bit_reader_get_bits_uint64_unchecked
44 * - gst_bit_reader_peek_bits_uint64_unchecked
45 *
46 * #GstBitReader provides a bit reader that can read any number of bits
47 * from a memory buffer. It provides functions for reading any number of bits
48 * into 8, 16, 32 and 64 bit variables.
49 */
50
51 /**
52 * gst_bit_reader_new: (skip)
53 * @data: (array length=size): Data from which the #GstBitReader
54 * should read
55 * @size: Size of @data in bytes
56 *
57 * Create a new #GstBitReader instance, which will read from @data.
58 *
59 * Free-function: gst_bit_reader_free
60 *
61 * Returns: (transfer full): a new #GstBitReader instance
62 */
63 GstBitReader *
gst_bit_reader_new(const guint8 * data,guint size)64 gst_bit_reader_new (const guint8 * data, guint size)
65 {
66 GstBitReader *ret = g_slice_new0 (GstBitReader);
67
68 ret->data = data;
69 ret->size = size;
70
71 return ret;
72 }
73
74 /**
75 * gst_bit_reader_free:
76 * @reader: (in) (transfer full): a #GstBitReader instance
77 *
78 * Frees a #GstBitReader instance, which was previously allocated by
79 * gst_bit_reader_new().
80 */
81 void
gst_bit_reader_free(GstBitReader * reader)82 gst_bit_reader_free (GstBitReader * reader)
83 {
84 g_return_if_fail (reader != NULL);
85
86 g_slice_free (GstBitReader, reader);
87 }
88
89 /**
90 * gst_bit_reader_init:
91 * @reader: a #GstBitReader instance
92 * @data: (in) (array length=size): data from which the bit reader should read
93 * @size: Size of @data in bytes
94 *
95 * Initializes a #GstBitReader instance to read from @data. This function
96 * can be called on already initialized instances.
97 */
98 void
gst_bit_reader_init(GstBitReader * reader,const guint8 * data,guint size)99 gst_bit_reader_init (GstBitReader * reader, const guint8 * data, guint size)
100 {
101 g_return_if_fail (reader != NULL);
102
103 reader->data = data;
104 reader->size = size;
105 reader->byte = reader->bit = 0;
106 }
107
108 /**
109 * gst_bit_reader_set_pos:
110 * @reader: a #GstBitReader instance
111 * @pos: The new position in bits
112 *
113 * Sets the new position of a #GstBitReader instance to @pos in bits.
114 *
115 * Returns: %TRUE if the position could be set successfully, %FALSE
116 * otherwise.
117 */
118 gboolean
gst_bit_reader_set_pos(GstBitReader * reader,guint pos)119 gst_bit_reader_set_pos (GstBitReader * reader, guint pos)
120 {
121 g_return_val_if_fail (reader != NULL, FALSE);
122
123 if (pos > reader->size * 8)
124 return FALSE;
125
126 reader->byte = pos / 8;
127 reader->bit = pos % 8;
128
129 return TRUE;
130 }
131
132 /**
133 * gst_bit_reader_get_pos:
134 * @reader: a #GstBitReader instance
135 *
136 * Returns the current position of a #GstBitReader instance in bits.
137 *
138 * Returns: The current position of @reader in bits.
139 */
140 guint
gst_bit_reader_get_pos(const GstBitReader * reader)141 gst_bit_reader_get_pos (const GstBitReader * reader)
142 {
143 return _gst_bit_reader_get_pos_inline (reader);
144 }
145
146 /**
147 * gst_bit_reader_get_remaining:
148 * @reader: a #GstBitReader instance
149 *
150 * Returns the remaining number of bits of a #GstBitReader instance.
151 *
152 * Returns: The remaining number of bits of @reader instance.
153 */
154 guint
gst_bit_reader_get_remaining(const GstBitReader * reader)155 gst_bit_reader_get_remaining (const GstBitReader * reader)
156 {
157 return _gst_bit_reader_get_remaining_inline (reader);
158 }
159
160 /**
161 * gst_bit_reader_get_size:
162 * @reader: a #GstBitReader instance
163 *
164 * Returns the total number of bits of a #GstBitReader instance.
165 *
166 * Returns: The total number of bits of @reader instance.
167 */
168 guint
gst_bit_reader_get_size(const GstBitReader * reader)169 gst_bit_reader_get_size (const GstBitReader * reader)
170 {
171 return _gst_bit_reader_get_size_inline (reader);
172 }
173
174 /**
175 * gst_bit_reader_skip:
176 * @reader: a #GstBitReader instance
177 * @nbits: the number of bits to skip
178 *
179 * Skips @nbits bits of the #GstBitReader instance.
180 *
181 * Returns: %TRUE if @nbits bits could be skipped, %FALSE otherwise.
182 */
183 gboolean
gst_bit_reader_skip(GstBitReader * reader,guint nbits)184 gst_bit_reader_skip (GstBitReader * reader, guint nbits)
185 {
186 return _gst_bit_reader_skip_inline (reader, nbits);
187 }
188
189 /**
190 * gst_bit_reader_skip_to_byte:
191 * @reader: a #GstBitReader instance
192 *
193 * Skips until the next byte.
194 *
195 * Returns: %TRUE if successful, %FALSE otherwise.
196 */
197 gboolean
gst_bit_reader_skip_to_byte(GstBitReader * reader)198 gst_bit_reader_skip_to_byte (GstBitReader * reader)
199 {
200 return _gst_bit_reader_skip_to_byte_inline (reader);
201 }
202
203 /**
204 * gst_bit_reader_get_bits_uint8:
205 * @reader: a #GstBitReader instance
206 * @val: (out): Pointer to a #guint8 to store the result
207 * @nbits: number of bits to read
208 *
209 * Read @nbits bits into @val and update the current position.
210 *
211 * Returns: %TRUE if successful, %FALSE otherwise.
212 */
213
214 /**
215 * gst_bit_reader_get_bits_uint16:
216 * @reader: a #GstBitReader instance
217 * @val: (out): Pointer to a #guint16 to store the result
218 * @nbits: number of bits to read
219 *
220 * Read @nbits bits into @val and update the current position.
221 *
222 * Returns: %TRUE if successful, %FALSE otherwise.
223 */
224
225 /**
226 * gst_bit_reader_get_bits_uint32:
227 * @reader: a #GstBitReader instance
228 * @val: (out): Pointer to a #guint32 to store the result
229 * @nbits: number of bits to read
230 *
231 * Read @nbits bits into @val and update the current position.
232 *
233 * Returns: %TRUE if successful, %FALSE otherwise.
234 */
235
236 /**
237 * gst_bit_reader_get_bits_uint64:
238 * @reader: a #GstBitReader instance
239 * @val: (out): Pointer to a #guint64 to store the result
240 * @nbits: number of bits to read
241 *
242 * Read @nbits bits into @val and update the current position.
243 *
244 * Returns: %TRUE if successful, %FALSE otherwise.
245 */
246
247 /**
248 * gst_bit_reader_peek_bits_uint8:
249 * @reader: a #GstBitReader instance
250 * @val: (out): Pointer to a #guint8 to store the result
251 * @nbits: number of bits to read
252 *
253 * Read @nbits bits into @val but keep the current position.
254 *
255 * Returns: %TRUE if successful, %FALSE otherwise.
256 */
257
258 /**
259 * gst_bit_reader_peek_bits_uint16:
260 * @reader: a #GstBitReader instance
261 * @val: (out): Pointer to a #guint16 to store the result
262 * @nbits: number of bits to read
263 *
264 * Read @nbits bits into @val but keep the current position.
265 *
266 * Returns: %TRUE if successful, %FALSE otherwise.
267 */
268
269 /**
270 * gst_bit_reader_peek_bits_uint32:
271 * @reader: a #GstBitReader instance
272 * @val: (out): Pointer to a #guint32 to store the result
273 * @nbits: number of bits to read
274 *
275 * Read @nbits bits into @val but keep the current position.
276 *
277 * Returns: %TRUE if successful, %FALSE otherwise.
278 */
279
280 /**
281 * gst_bit_reader_peek_bits_uint64:
282 * @reader: a #GstBitReader instance
283 * @val: (out): Pointer to a #guint64 to store the result
284 * @nbits: number of bits to read
285 *
286 * Read @nbits bits into @val but keep the current position.
287 *
288 * Returns: %TRUE if successful, %FALSE otherwise.
289 */
290
291 #define GST_BIT_READER_READ_BITS(bits) \
292 gboolean \
293 gst_bit_reader_peek_bits_uint##bits (const GstBitReader *reader, guint##bits *val, guint nbits) \
294 { \
295 return _gst_bit_reader_peek_bits_uint##bits##_inline (reader, val, nbits); \
296 } \
297 \
298 gboolean \
299 gst_bit_reader_get_bits_uint##bits (GstBitReader *reader, guint##bits *val, guint nbits) \
300 { \
301 return _gst_bit_reader_get_bits_uint##bits##_inline (reader, val, nbits); \
302 }
303
304 GST_BIT_READER_READ_BITS (8);
305 GST_BIT_READER_READ_BITS (16);
306 GST_BIT_READER_READ_BITS (32);
307 GST_BIT_READER_READ_BITS (64);
308