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 gpointer _gst_reserved[GST_PADDING];
52 GstBitReader * gst_bit_reader_new (const guint8 *data, guint size);
53 void gst_bit_reader_free (GstBitReader *reader);
55 void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
57 gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
59 guint gst_bit_reader_get_pos (const GstBitReader *reader);
60 guint gst_bit_reader_get_remaining (const GstBitReader *reader);
62 guint gst_bit_reader_get_size (const GstBitReader *reader);
64 gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
65 gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
67 gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
68 gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
69 gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
70 gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
72 gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
73 gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
74 gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
75 gboolean gst_bit_reader_peek_bits_uint64 (const GstBitReader *reader, guint64 *val, guint nbits);
78 * GST_BIT_READER_INIT:
79 * @data: Data from which the #GstBitReader should read
80 * @size: Size of @data in bytes
82 * A #GstBitReader must be initialized with this macro, before it can be
83 * used. This macro can used be to initialize a variable, but it cannot
84 * be assigned to a variable. In that case you have to use
85 * gst_bit_reader_init().
89 #define GST_BIT_READER_INIT(data, size) {data, size, 0, 0}
91 /* Unchecked variants */
94 gst_bit_reader_skip_unchecked (GstBitReader * reader, guint nbits)
97 reader->byte += reader->bit / 8;
98 reader->bit = reader->bit % 8;
102 gst_bit_reader_skip_to_byte_unchecked (GstBitReader * reader)
110 #define __GST_BIT_READER_READ_BITS_UNCHECKED(bits) \
111 static inline guint##bits \
112 gst_bit_reader_peek_bits_uint##bits##_unchecked (const GstBitReader *reader, guint nbits) \
114 guint##bits ret = 0; \
115 const guint8 *data; \
118 data = reader->data; \
119 byte = reader->byte; \
122 while (nbits > 0) { \
123 guint toread = MIN (nbits, 8 - bit); \
126 ret |= (data[byte] & (0xff >> bit)) >> (8 - toread - bit); \
139 static inline guint##bits \
140 gst_bit_reader_get_bits_uint##bits##_unchecked (GstBitReader *reader, guint nbits) \
144 ret = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
146 gst_bit_reader_skip_unchecked (reader, nbits); \
151 __GST_BIT_READER_READ_BITS_UNCHECKED (8)
152 __GST_BIT_READER_READ_BITS_UNCHECKED (16)
153 __GST_BIT_READER_READ_BITS_UNCHECKED (32)
154 __GST_BIT_READER_READ_BITS_UNCHECKED (64)
156 #undef __GST_BIT_READER_READ_BITS_UNCHECKED
158 /* unchecked variants -- do not use */
161 _gst_bit_reader_get_size_unchecked (const GstBitReader * reader)
163 return reader->size * 8;
167 _gst_bit_reader_get_pos_unchecked (const GstBitReader * reader)
169 return reader->byte * 8 + reader->bit;
173 _gst_bit_reader_get_remaining_unchecked (const GstBitReader * reader)
175 return reader->size * 8 - (reader->byte * 8 + reader->bit);
178 /* inlined variants -- do not use directly */
180 _gst_bit_reader_get_size_inline (const GstBitReader * reader)
182 g_return_val_if_fail (reader != NULL, 0);
184 return _gst_bit_reader_get_size_unchecked (reader);
188 _gst_bit_reader_get_pos_inline (const GstBitReader * reader)
190 g_return_val_if_fail (reader != NULL, 0);
192 return _gst_bit_reader_get_pos_unchecked (reader);
196 _gst_bit_reader_get_remaining_inline (const GstBitReader * reader)
198 g_return_val_if_fail (reader != NULL, 0);
200 return _gst_bit_reader_get_remaining_unchecked (reader);
203 static inline gboolean
204 _gst_bit_reader_skip_inline (GstBitReader * reader, guint nbits)
206 g_return_val_if_fail (reader != NULL, FALSE);
208 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits)
211 gst_bit_reader_skip_unchecked (reader, nbits);
216 static inline gboolean
217 _gst_bit_reader_skip_to_byte_inline (GstBitReader * reader)
219 g_return_val_if_fail (reader != NULL, FALSE);
221 if (reader->byte > reader->size)
224 gst_bit_reader_skip_to_byte_unchecked (reader);
229 #define __GST_BIT_READER_READ_BITS_INLINE(bits) \
230 static inline gboolean \
231 _gst_bit_reader_get_bits_uint##bits##_inline (GstBitReader *reader, guint##bits *val, guint nbits) \
233 g_return_val_if_fail (reader != NULL, FALSE); \
234 g_return_val_if_fail (val != NULL, FALSE); \
235 g_return_val_if_fail (nbits <= bits, FALSE); \
237 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
240 *val = gst_bit_reader_get_bits_uint##bits##_unchecked (reader, nbits); \
244 static inline gboolean \
245 _gst_bit_reader_peek_bits_uint##bits##_inline (const GstBitReader *reader, guint##bits *val, guint nbits) \
247 g_return_val_if_fail (reader != NULL, FALSE); \
248 g_return_val_if_fail (val != NULL, FALSE); \
249 g_return_val_if_fail (nbits <= bits, FALSE); \
251 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
254 *val = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
258 __GST_BIT_READER_READ_BITS_INLINE (8)
259 __GST_BIT_READER_READ_BITS_INLINE (16)
260 __GST_BIT_READER_READ_BITS_INLINE (32)
261 __GST_BIT_READER_READ_BITS_INLINE (64)
263 #undef __GST_BIT_READER_READ_BITS_INLINE
265 #ifndef GST_BIT_READER_DISABLE_INLINES
267 #define gst_bit_reader_get_size(reader) \
268 _gst_bit_reader_get_size_inline (reader)
269 #define gst_bit_reader_get_pos(reader) \
270 _gst_bit_reader_get_pos_inline (reader)
271 #define gst_bit_reader_get_remaining(reader) \
272 _gst_bit_reader_get_remaining_inline (reader)
274 /* we use defines here so we can add the G_LIKELY() */
276 #define gst_bit_reader_skip(reader, nbits)\
277 G_LIKELY (_gst_bit_reader_skip_inline(reader, nbits))
278 #define gst_bit_reader_skip_to_byte(reader)\
279 G_LIKELY (_gst_bit_reader_skip_to_byte_inline(reader))
281 #define gst_bit_reader_get_bits_uint8(reader, val, nbits) \
282 G_LIKELY (_gst_bit_reader_get_bits_uint8_inline (reader, val, nbits))
283 #define gst_bit_reader_get_bits_uint16(reader, val, nbits) \
284 G_LIKELY (_gst_bit_reader_get_bits_uint16_inline (reader, val, nbits))
285 #define gst_bit_reader_get_bits_uint32(reader, val, nbits) \
286 G_LIKELY (_gst_bit_reader_get_bits_uint32_inline (reader, val, nbits))
287 #define gst_bit_reader_get_bits_uint64(reader, val, nbits) \
288 G_LIKELY (_gst_bit_reader_get_bits_uint64_inline (reader, val, nbits))
290 #define gst_bit_reader_peek_bits_uint8(reader, val, nbits) \
291 G_LIKELY (_gst_bit_reader_peek_bits_uint8_inline (reader, val, nbits))
292 #define gst_bit_reader_peek_bits_uint16(reader, val, nbits) \
293 G_LIKELY (_gst_bit_reader_peek_bits_uint16_inline (reader, val, nbits))
294 #define gst_bit_reader_peek_bits_uint32(reader, val, nbits) \
295 G_LIKELY (_gst_bit_reader_peek_bits_uint32_inline (reader, val, nbits))
296 #define gst_bit_reader_peek_bits_uint64(reader, val, nbits) \
297 G_LIKELY (_gst_bit_reader_peek_bits_uint64_inline (reader, val, nbits))
302 #endif /* __GST_BIT_READER_H__ */