gstreamer/libs/gst/base/gstbitreader.h
Tim-Philipp Müller 7e2ace8618 base: GST_EXPORT -> GST_BASE_API
We need different export decorators for the different libs.
For now no actual change though, just rename before the release,
and add prelude headers to define the new decorator to GST_EXPORT.
2018-03-13 00:46:00 +00:00

328 lines
9.5 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>
#include <gst/base/base-prelude.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_BASE_API
GstBitReader * gst_bit_reader_new (const guint8 *data, guint size) G_GNUC_MALLOC;
GST_BASE_API
void gst_bit_reader_free (GstBitReader *reader);
GST_BASE_API
void gst_bit_reader_init (GstBitReader *reader, const guint8 *data, guint size);
GST_BASE_API
gboolean gst_bit_reader_set_pos (GstBitReader *reader, guint pos);
GST_BASE_API
guint gst_bit_reader_get_pos (const GstBitReader *reader);
GST_BASE_API
guint gst_bit_reader_get_remaining (const GstBitReader *reader);
GST_BASE_API
guint gst_bit_reader_get_size (const GstBitReader *reader);
GST_BASE_API
gboolean gst_bit_reader_skip (GstBitReader *reader, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_skip_to_byte (GstBitReader *reader);
GST_BASE_API
gboolean gst_bit_reader_get_bits_uint8 (GstBitReader *reader, guint8 *val, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_get_bits_uint16 (GstBitReader *reader, guint16 *val, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_get_bits_uint32 (GstBitReader *reader, guint32 *val, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_get_bits_uint64 (GstBitReader *reader, guint64 *val, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_peek_bits_uint8 (const GstBitReader *reader, guint8 *val, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_peek_bits_uint16 (const GstBitReader *reader, guint16 *val, guint nbits);
GST_BASE_API
gboolean gst_bit_reader_peek_bits_uint32 (const GstBitReader *reader, guint32 *val, guint nbits);
GST_BASE_API
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__ */