3 * Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>.
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.
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.
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.
21 #ifndef __GST_BIT_READER_H__
22 #define __GST_BIT_READER_H__
26 /* FIXME: inline functions */
30 #define GST_BIT_READER(reader) ((GstBitReader *) (reader))
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
39 * A bit reader instance.
45 guint byte; /* Byte position */
46 guint bit; /* Bit position in the current byte */
49 GstBitReader * gst_bit_reader_new (const guint8 *data, guint size);
50 void gst_bit_reader_free (GstBitReader *reader);
52 void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
54 gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
56 guint gst_bit_reader_get_pos (const GstBitReader *reader);
57 guint gst_bit_reader_get_remaining (const GstBitReader *reader);
59 guint gst_bit_reader_get_size (const GstBitReader *reader);
61 gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
62 gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
64 gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
65 gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
66 gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
67 gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
69 gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
70 gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
71 gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
72 gboolean gst_bit_reader_peek_bits_uint64 (const GstBitReader *reader, guint64 *val, guint nbits);
75 * GST_BIT_READER_INIT:
76 * @data: Data from which the #GstBitReader should read
77 * @size: Size of @data in bytes
79 * A #GstBitReader must be initialized with this macro, before it can be
80 * used. This macro can used be to initialize a variable, but it cannot
81 * be assigned to a variable. In that case you have to use
82 * gst_bit_reader_init().
86 #define GST_BIT_READER_INIT(data, size) {data, size, 0, 0}
88 /* Unchecked variants */
91 gst_bit_reader_skip_unchecked (GstBitReader * reader, guint nbits)
94 reader->byte += reader->bit / 8;
95 reader->bit = reader->bit % 8;
99 gst_bit_reader_skip_to_byte_unchecked (GstBitReader * reader)
107 #define __GST_BIT_READER_READ_BITS_UNCHECKED(bits) \
108 static inline guint##bits \
109 gst_bit_reader_peek_bits_uint##bits##_unchecked (const GstBitReader *reader, guint nbits) \
111 guint##bits ret = 0; \
112 const guint8 *data; \
115 data = reader->data; \
116 byte = reader->byte; \
119 while (nbits > 0) { \
120 guint toread = MIN (nbits, 8 - bit); \
123 ret |= (data[byte] & (0xff >> bit)) >> (8 - toread - bit); \
136 static inline guint##bits \
137 gst_bit_reader_get_bits_uint##bits##_unchecked (GstBitReader *reader, guint nbits) \
141 ret = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
143 gst_bit_reader_skip_unchecked (reader, nbits); \
148 __GST_BIT_READER_READ_BITS_UNCHECKED (8)
149 __GST_BIT_READER_READ_BITS_UNCHECKED (16)
150 __GST_BIT_READER_READ_BITS_UNCHECKED (32)
151 __GST_BIT_READER_READ_BITS_UNCHECKED (64)
153 #undef __GST_BIT_READER_READ_BITS_UNCHECKED
155 /* unchecked variants -- do not use */
158 _gst_bit_reader_get_size_unchecked (const GstBitReader * reader)
160 return reader->size * 8;
164 _gst_bit_reader_get_pos_unchecked (const GstBitReader * reader)
166 return reader->byte * 8 + reader->bit;
170 _gst_bit_reader_get_remaining_unchecked (const GstBitReader * reader)
172 return reader->size * 8 - (reader->byte * 8 + reader->bit);
175 /* inlined variants -- do not use directly */
177 _gst_bit_reader_get_size_inline (const GstBitReader * reader)
179 g_return_val_if_fail (reader != NULL, 0);
181 return _gst_bit_reader_get_size_unchecked (reader);
185 _gst_bit_reader_get_pos_inline (const GstBitReader * reader)
187 g_return_val_if_fail (reader != NULL, 0);
189 return _gst_bit_reader_get_pos_unchecked (reader);
193 _gst_bit_reader_get_remaining_inline (const GstBitReader * reader)
195 g_return_val_if_fail (reader != NULL, 0);
197 return _gst_bit_reader_get_remaining_unchecked (reader);
200 static inline gboolean
201 _gst_bit_reader_skip_inline (GstBitReader * reader, guint nbits)
203 g_return_val_if_fail (reader != NULL, FALSE);
205 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits)
208 gst_bit_reader_skip_unchecked (reader, nbits);
213 static inline gboolean
214 _gst_bit_reader_skip_to_byte_inline (GstBitReader * reader)
216 g_return_val_if_fail (reader != NULL, FALSE);
218 if (reader->byte > reader->size)
221 gst_bit_reader_skip_to_byte_unchecked (reader);
226 #define __GST_BIT_READER_READ_BITS_INLINE(bits) \
227 static inline gboolean \
228 _gst_bit_reader_get_bits_uint##bits##_inline (GstBitReader *reader, guint##bits *val, guint nbits) \
230 g_return_val_if_fail (reader != NULL, FALSE); \
231 g_return_val_if_fail (val != NULL, FALSE); \
232 g_return_val_if_fail (nbits <= bits, FALSE); \
234 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
237 *val = gst_bit_reader_get_bits_uint##bits##_unchecked (reader, nbits); \
241 static inline gboolean \
242 _gst_bit_reader_peek_bits_uint##bits##_inline (const GstBitReader *reader, guint##bits *val, guint nbits) \
244 g_return_val_if_fail (reader != NULL, FALSE); \
245 g_return_val_if_fail (val != NULL, FALSE); \
246 g_return_val_if_fail (nbits <= bits, FALSE); \
248 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
251 *val = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
255 __GST_BIT_READER_READ_BITS_INLINE (8)
256 __GST_BIT_READER_READ_BITS_INLINE (16)
257 __GST_BIT_READER_READ_BITS_INLINE (32)
258 __GST_BIT_READER_READ_BITS_INLINE (64)
260 #undef __GST_BIT_READER_READ_BITS_INLINE
262 #ifndef GST_BIT_READER_DISABLE_INLINES
264 #define gst_bit_reader_get_size(reader) \
265 _gst_bit_reader_get_size_inline (reader)
266 #define gst_bit_reader_get_pos(reader) \
267 _gst_bit_reader_get_pos_inline (reader)
268 #define gst_bit_reader_get_remaining(reader) \
269 _gst_bit_reader_get_remaining_inline (reader)
271 /* we use defines here so we can add the G_LIKELY() */
273 #define gst_bit_reader_skip(reader, nbits)\
274 G_LIKELY (_gst_bit_reader_skip_inline(reader, nbits))
275 #define gst_bit_reader_skip_to_byte(reader)\
276 G_LIKELY (_gst_bit_reader_skip_to_byte_inline(reader))
278 #define gst_bit_reader_get_bits_uint8(reader, val, nbits) \
279 G_LIKELY (_gst_bit_reader_get_bits_uint8_inline (reader, val, nbits))
280 #define gst_bit_reader_get_bits_uint16(reader, val, nbits) \
281 G_LIKELY (_gst_bit_reader_get_bits_uint16_inline (reader, val, nbits))
282 #define gst_bit_reader_get_bits_uint32(reader, val, nbits) \
283 G_LIKELY (_gst_bit_reader_get_bits_uint32_inline (reader, val, nbits))
284 #define gst_bit_reader_get_bits_uint64(reader, val, nbits) \
285 G_LIKELY (_gst_bit_reader_get_bits_uint64_inline (reader, val, nbits))
287 #define gst_bit_reader_peek_bits_uint8(reader, val, nbits) \
288 G_LIKELY (_gst_bit_reader_peek_bits_uint8_inline (reader, val, nbits))
289 #define gst_bit_reader_peek_bits_uint16(reader, val, nbits) \
290 G_LIKELY (_gst_bit_reader_peek_bits_uint16_inline (reader, val, nbits))
291 #define gst_bit_reader_peek_bits_uint32(reader, val, nbits) \
292 G_LIKELY (_gst_bit_reader_peek_bits_uint32_inline (reader, val, nbits))
293 #define gst_bit_reader_peek_bits_uint64(reader, val, nbits) \
294 G_LIKELY (_gst_bit_reader_peek_bits_uint64_inline (reader, val, nbits))
299 #endif /* __GST_BIT_READER_H__ */