gstreamer/libs/gst/base/gstbitreader.h

327 lines
9.4 KiB
C

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