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., 51 Franklin St, Fifth Floor,
18 * Boston, MA 02110-1301, 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: (array length=size): Data from which the bit reader will
36 * @size: Size of @data in bytes
37 * @byte: Current byte position
38 * @bit: Bit position in the current byte
40 * A bit reader instance.
46 guint byte; /* Byte position */
47 guint bit; /* Bit position in the current byte */
50 gpointer _gst_reserved[GST_PADDING];
53 GstBitReader * gst_bit_reader_new (const guint8 *data, guint size) G_GNUC_MALLOC;
54 void gst_bit_reader_free (GstBitReader *reader);
56 void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
58 gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
59 guint gst_bit_reader_get_pos (const GstBitReader *reader);
61 guint gst_bit_reader_get_remaining (const GstBitReader *reader);
63 guint gst_bit_reader_get_size (const GstBitReader *reader);
65 gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
66 gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
68 gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
69 gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
70 gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
71 gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
73 gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
74 gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
75 gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
76 gboolean gst_bit_reader_peek_bits_uint64 (const GstBitReader *reader, guint64 *val, guint nbits);
79 * GST_BIT_READER_INIT:
80 * @data: Data from which the #GstBitReader should read
81 * @size: Size of @data in bytes
83 * A #GstBitReader must be initialized with this macro, before it can be
84 * used. This macro can used be to initialize a variable, but it cannot
85 * be assigned to a variable. In that case you have to use
86 * gst_bit_reader_init().
88 #define GST_BIT_READER_INIT(data, size) {data, size, 0, 0}
90 /* Unchecked variants */
93 gst_bit_reader_skip_unchecked (GstBitReader * reader, guint nbits)
96 reader->byte += reader->bit / 8;
97 reader->bit = reader->bit % 8;
101 gst_bit_reader_skip_to_byte_unchecked (GstBitReader * reader)
109 #define __GST_BIT_READER_READ_BITS_UNCHECKED(bits) \
110 static inline guint##bits \
111 gst_bit_reader_peek_bits_uint##bits##_unchecked (const GstBitReader *reader, guint nbits) \
113 guint##bits ret = 0; \
114 const guint8 *data; \
117 data = reader->data; \
118 byte = reader->byte; \
121 while (nbits > 0) { \
122 guint toread = MIN (nbits, 8 - bit); \
125 ret |= (data[byte] & (0xff >> bit)) >> (8 - toread - bit); \
138 static inline guint##bits \
139 gst_bit_reader_get_bits_uint##bits##_unchecked (GstBitReader *reader, guint nbits) \
143 ret = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
145 gst_bit_reader_skip_unchecked (reader, nbits); \
150 __GST_BIT_READER_READ_BITS_UNCHECKED (8)
151 __GST_BIT_READER_READ_BITS_UNCHECKED (16)
152 __GST_BIT_READER_READ_BITS_UNCHECKED (32)
153 __GST_BIT_READER_READ_BITS_UNCHECKED (64)
155 #undef __GST_BIT_READER_READ_BITS_UNCHECKED
157 /* unchecked variants -- do not use */
160 _gst_bit_reader_get_size_unchecked (const GstBitReader * reader)
162 return reader->size * 8;
166 _gst_bit_reader_get_pos_unchecked (const GstBitReader * reader)
168 return reader->byte * 8 + reader->bit;
172 _gst_bit_reader_get_remaining_unchecked (const GstBitReader * reader)
174 return reader->size * 8 - (reader->byte * 8 + reader->bit);
177 /* inlined variants -- do not use directly */
179 _gst_bit_reader_get_size_inline (const GstBitReader * reader)
181 g_return_val_if_fail (reader != NULL, 0);
183 return _gst_bit_reader_get_size_unchecked (reader);
187 _gst_bit_reader_get_pos_inline (const GstBitReader * reader)
189 g_return_val_if_fail (reader != NULL, 0);
191 return _gst_bit_reader_get_pos_unchecked (reader);
195 _gst_bit_reader_get_remaining_inline (const GstBitReader * reader)
197 g_return_val_if_fail (reader != NULL, 0);
199 return _gst_bit_reader_get_remaining_unchecked (reader);
202 static inline gboolean
203 _gst_bit_reader_skip_inline (GstBitReader * reader, guint nbits)
205 g_return_val_if_fail (reader != NULL, FALSE);
207 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits)
210 gst_bit_reader_skip_unchecked (reader, nbits);
215 static inline gboolean
216 _gst_bit_reader_skip_to_byte_inline (GstBitReader * reader)
218 g_return_val_if_fail (reader != NULL, FALSE);
220 if (reader->byte > reader->size)
223 gst_bit_reader_skip_to_byte_unchecked (reader);
228 #define __GST_BIT_READER_READ_BITS_INLINE(bits) \
229 static inline gboolean \
230 _gst_bit_reader_get_bits_uint##bits##_inline (GstBitReader *reader, guint##bits *val, guint nbits) \
232 g_return_val_if_fail (reader != NULL, FALSE); \
233 g_return_val_if_fail (val != NULL, FALSE); \
234 g_return_val_if_fail (nbits <= bits, FALSE); \
236 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
239 *val = gst_bit_reader_get_bits_uint##bits##_unchecked (reader, nbits); \
243 static inline gboolean \
244 _gst_bit_reader_peek_bits_uint##bits##_inline (const GstBitReader *reader, guint##bits *val, guint nbits) \
246 g_return_val_if_fail (reader != NULL, FALSE); \
247 g_return_val_if_fail (val != NULL, FALSE); \
248 g_return_val_if_fail (nbits <= bits, FALSE); \
250 if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
253 *val = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
257 __GST_BIT_READER_READ_BITS_INLINE (8)
258 __GST_BIT_READER_READ_BITS_INLINE (16)
259 __GST_BIT_READER_READ_BITS_INLINE (32)
260 __GST_BIT_READER_READ_BITS_INLINE (64)
262 #undef __GST_BIT_READER_READ_BITS_INLINE
264 #ifndef GST_BIT_READER_DISABLE_INLINES
266 #define gst_bit_reader_get_size(reader) \
267 _gst_bit_reader_get_size_inline (reader)
268 #define gst_bit_reader_get_pos(reader) \
269 _gst_bit_reader_get_pos_inline (reader)
270 #define gst_bit_reader_get_remaining(reader) \
271 _gst_bit_reader_get_remaining_inline (reader)
273 /* we use defines here so we can add the G_LIKELY() */
275 #define gst_bit_reader_skip(reader, nbits)\
276 G_LIKELY (_gst_bit_reader_skip_inline(reader, nbits))
277 #define gst_bit_reader_skip_to_byte(reader)\
278 G_LIKELY (_gst_bit_reader_skip_to_byte_inline(reader))
280 #define gst_bit_reader_get_bits_uint8(reader, val, nbits) \
281 G_LIKELY (_gst_bit_reader_get_bits_uint8_inline (reader, val, nbits))
282 #define gst_bit_reader_get_bits_uint16(reader, val, nbits) \
283 G_LIKELY (_gst_bit_reader_get_bits_uint16_inline (reader, val, nbits))
284 #define gst_bit_reader_get_bits_uint32(reader, val, nbits) \
285 G_LIKELY (_gst_bit_reader_get_bits_uint32_inline (reader, val, nbits))
286 #define gst_bit_reader_get_bits_uint64(reader, val, nbits) \
287 G_LIKELY (_gst_bit_reader_get_bits_uint64_inline (reader, val, nbits))
289 #define gst_bit_reader_peek_bits_uint8(reader, val, nbits) \
290 G_LIKELY (_gst_bit_reader_peek_bits_uint8_inline (reader, val, nbits))
291 #define gst_bit_reader_peek_bits_uint16(reader, val, nbits) \
292 G_LIKELY (_gst_bit_reader_peek_bits_uint16_inline (reader, val, nbits))
293 #define gst_bit_reader_peek_bits_uint32(reader, val, nbits) \
294 G_LIKELY (_gst_bit_reader_peek_bits_uint32_inline (reader, val, nbits))
295 #define gst_bit_reader_peek_bits_uint64(reader, val, nbits) \
296 G_LIKELY (_gst_bit_reader_peek_bits_uint64_inline (reader, val, nbits))
301 #endif /* __GST_BIT_READER_H__ */