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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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327 lines
9.4 KiB
C
327 lines
9.4 KiB
C
/* GStreamer
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*
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* Copyright (C) 2008 Sebastian Dröge <sebastian.droege@collabora.co.uk>.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __GST_BIT_READER_H__
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#define __GST_BIT_READER_H__
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#include <gst/gst.h>
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/* FIXME: inline functions */
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G_BEGIN_DECLS
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#define GST_BIT_READER(reader) ((GstBitReader *) (reader))
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/**
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* GstBitReader:
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* @data: (array length=size): Data from which the bit reader will
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* read
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* @size: Size of @data in bytes
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* @byte: Current byte position
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* @bit: Bit position in the current byte
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*
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* A bit reader instance.
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*/
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typedef struct {
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const guint8 *data;
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guint size;
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guint byte; /* Byte position */
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guint bit; /* Bit position in the current byte */
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/* < private > */
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gpointer _gst_reserved[GST_PADDING];
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} GstBitReader;
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GST_EXPORT
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GstBitReader * gst_bit_reader_new (const guint8 *data, guint size) G_GNUC_MALLOC;
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GST_EXPORT
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void gst_bit_reader_free (GstBitReader *reader);
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GST_EXPORT
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void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
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GST_EXPORT
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gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
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GST_EXPORT
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guint gst_bit_reader_get_pos (const GstBitReader *reader);
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GST_EXPORT
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guint gst_bit_reader_get_remaining (const GstBitReader *reader);
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GST_EXPORT
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guint gst_bit_reader_get_size (const GstBitReader *reader);
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GST_EXPORT
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gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
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GST_EXPORT
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gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
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GST_EXPORT
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gboolean gst_bit_reader_peek_bits_uint64 (const GstBitReader *reader, guint64 *val, guint nbits);
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/**
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* GST_BIT_READER_INIT:
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* @data: Data from which the #GstBitReader should read
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* @size: Size of @data in bytes
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*
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* A #GstBitReader must be initialized with this macro, before it can be
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* used. This macro can used be to initialize a variable, but it cannot
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* be assigned to a variable. In that case you have to use
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* gst_bit_reader_init().
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*/
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#define GST_BIT_READER_INIT(data, size) {data, size, 0, 0}
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/* Unchecked variants */
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static inline void
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gst_bit_reader_skip_unchecked (GstBitReader * reader, guint nbits)
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{
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reader->bit += nbits;
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reader->byte += reader->bit / 8;
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reader->bit = reader->bit % 8;
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}
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static inline void
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gst_bit_reader_skip_to_byte_unchecked (GstBitReader * reader)
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{
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if (reader->bit) {
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reader->bit = 0;
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reader->byte++;
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}
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}
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#define __GST_BIT_READER_READ_BITS_UNCHECKED(bits) \
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static inline guint##bits \
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gst_bit_reader_peek_bits_uint##bits##_unchecked (const GstBitReader *reader, guint nbits) \
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{ \
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guint##bits ret = 0; \
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const guint8 *data; \
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guint byte, bit; \
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\
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data = reader->data; \
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byte = reader->byte; \
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bit = reader->bit; \
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\
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while (nbits > 0) { \
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guint toread = MIN (nbits, 8 - bit); \
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\
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ret <<= toread; \
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ret |= (data[byte] & (0xff >> bit)) >> (8 - toread - bit); \
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\
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bit += toread; \
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if (bit >= 8) { \
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byte++; \
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bit = 0; \
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} \
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nbits -= toread; \
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} \
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\
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return ret; \
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} \
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\
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static inline guint##bits \
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gst_bit_reader_get_bits_uint##bits##_unchecked (GstBitReader *reader, guint nbits) \
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{ \
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guint##bits ret; \
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\
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ret = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
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\
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gst_bit_reader_skip_unchecked (reader, nbits); \
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\
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return ret; \
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}
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__GST_BIT_READER_READ_BITS_UNCHECKED (8)
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__GST_BIT_READER_READ_BITS_UNCHECKED (16)
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__GST_BIT_READER_READ_BITS_UNCHECKED (32)
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__GST_BIT_READER_READ_BITS_UNCHECKED (64)
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#undef __GST_BIT_READER_READ_BITS_UNCHECKED
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/* unchecked variants -- do not use */
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static inline guint
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_gst_bit_reader_get_size_unchecked (const GstBitReader * reader)
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{
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return reader->size * 8;
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}
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static inline guint
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_gst_bit_reader_get_pos_unchecked (const GstBitReader * reader)
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{
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return reader->byte * 8 + reader->bit;
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}
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static inline guint
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_gst_bit_reader_get_remaining_unchecked (const GstBitReader * reader)
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{
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return reader->size * 8 - (reader->byte * 8 + reader->bit);
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}
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/* inlined variants -- do not use directly */
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static inline guint
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_gst_bit_reader_get_size_inline (const GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, 0);
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return _gst_bit_reader_get_size_unchecked (reader);
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}
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static inline guint
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_gst_bit_reader_get_pos_inline (const GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, 0);
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return _gst_bit_reader_get_pos_unchecked (reader);
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}
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static inline guint
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_gst_bit_reader_get_remaining_inline (const GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, 0);
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return _gst_bit_reader_get_remaining_unchecked (reader);
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}
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static inline gboolean
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_gst_bit_reader_skip_inline (GstBitReader * reader, guint nbits)
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{
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g_return_val_if_fail (reader != NULL, FALSE);
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if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits)
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return FALSE;
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gst_bit_reader_skip_unchecked (reader, nbits);
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return TRUE;
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}
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static inline gboolean
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_gst_bit_reader_skip_to_byte_inline (GstBitReader * reader)
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{
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g_return_val_if_fail (reader != NULL, FALSE);
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if (reader->byte > reader->size)
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return FALSE;
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gst_bit_reader_skip_to_byte_unchecked (reader);
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return TRUE;
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}
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#define __GST_BIT_READER_READ_BITS_INLINE(bits) \
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static inline gboolean \
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_gst_bit_reader_get_bits_uint##bits##_inline (GstBitReader *reader, guint##bits *val, guint nbits) \
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{ \
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g_return_val_if_fail (reader != NULL, FALSE); \
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g_return_val_if_fail (val != NULL, FALSE); \
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g_return_val_if_fail (nbits <= bits, FALSE); \
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\
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if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
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return FALSE; \
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\
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*val = gst_bit_reader_get_bits_uint##bits##_unchecked (reader, nbits); \
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return TRUE; \
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} \
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\
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static inline gboolean \
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_gst_bit_reader_peek_bits_uint##bits##_inline (const GstBitReader *reader, guint##bits *val, guint nbits) \
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{ \
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g_return_val_if_fail (reader != NULL, FALSE); \
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g_return_val_if_fail (val != NULL, FALSE); \
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g_return_val_if_fail (nbits <= bits, FALSE); \
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\
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if (_gst_bit_reader_get_remaining_unchecked (reader) < nbits) \
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return FALSE; \
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\
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*val = gst_bit_reader_peek_bits_uint##bits##_unchecked (reader, nbits); \
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return TRUE; \
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}
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__GST_BIT_READER_READ_BITS_INLINE (8)
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__GST_BIT_READER_READ_BITS_INLINE (16)
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__GST_BIT_READER_READ_BITS_INLINE (32)
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__GST_BIT_READER_READ_BITS_INLINE (64)
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#undef __GST_BIT_READER_READ_BITS_INLINE
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#ifndef GST_BIT_READER_DISABLE_INLINES
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#define gst_bit_reader_get_size(reader) \
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_gst_bit_reader_get_size_inline (reader)
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#define gst_bit_reader_get_pos(reader) \
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_gst_bit_reader_get_pos_inline (reader)
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#define gst_bit_reader_get_remaining(reader) \
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_gst_bit_reader_get_remaining_inline (reader)
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/* we use defines here so we can add the G_LIKELY() */
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#define gst_bit_reader_skip(reader, nbits)\
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G_LIKELY (_gst_bit_reader_skip_inline(reader, nbits))
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#define gst_bit_reader_skip_to_byte(reader)\
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G_LIKELY (_gst_bit_reader_skip_to_byte_inline(reader))
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#define gst_bit_reader_get_bits_uint8(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_get_bits_uint8_inline (reader, val, nbits))
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#define gst_bit_reader_get_bits_uint16(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_get_bits_uint16_inline (reader, val, nbits))
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#define gst_bit_reader_get_bits_uint32(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_get_bits_uint32_inline (reader, val, nbits))
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#define gst_bit_reader_get_bits_uint64(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_get_bits_uint64_inline (reader, val, nbits))
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#define gst_bit_reader_peek_bits_uint8(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_peek_bits_uint8_inline (reader, val, nbits))
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#define gst_bit_reader_peek_bits_uint16(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_peek_bits_uint16_inline (reader, val, nbits))
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#define gst_bit_reader_peek_bits_uint32(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_peek_bits_uint32_inline (reader, val, nbits))
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#define gst_bit_reader_peek_bits_uint64(reader, val, nbits) \
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G_LIKELY (_gst_bit_reader_peek_bits_uint64_inline (reader, val, nbits))
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#endif
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G_END_DECLS
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#endif /* __GST_BIT_READER_H__ */
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