gstreamer/gst-libs/gst/base/gstbitwriter.h
Wind Yuan 99947d0592 libs: add generic bitstream writer.
GstBitWriter provides a bit writer that can write any number of bits
to a pre-allocated memory buffer. Helper functions are also provided
to write any number of bits from 8, 16, 32 and 64 bit variables.

Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
2013-11-24 16:52:05 +01:00

361 lines
10 KiB
C

/*
* gstbitwriter.h - bitstream writer
*
* Copyright (C) 2013 Intel Corporation
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
#ifndef GST_BIT_WRITER_H
#define GST_BIT_WRITER_H
#include <gst/gst.h>
#include <string.h>
G_BEGIN_DECLS
#define GST_BIT_WRITER_DATA(writer) ((writer)->data)
#define GST_BIT_WRITER_BIT_SIZE(writer) ((writer)->bit_size)
#define GST_BIT_WRITER(writer) ((GstBitWriter *) (writer))
typedef struct _GstBitWriter GstBitWriter;
/**
* GstBitWriter:
* @data: Allocated @data for bit writer to write
* @bit_size: Size of written @data in bits
*
* Private:
* @bit_capacity: Capacity of the allocated @data
* @auto_grow: @data space can auto grow
*
* A bit writer instance.
*/
struct _GstBitWriter
{
guint8 *data;
guint bit_size;
/*< private >*/
guint bit_capacity;
gboolean auto_grow;
gpointer _gst_reserved[GST_PADDING];
};
GstBitWriter *
gst_bit_writer_new (guint32 reserved_bits) G_GNUC_MALLOC;
GstBitWriter *
gst_bit_writer_new_fill (guint8 * data, guint bits) G_GNUC_MALLOC;
void
gst_bit_writer_free (GstBitWriter * writer, gboolean free_data);
void
gst_bit_writer_init (GstBitWriter * bitwriter, guint32 reserved_bits);
void
gst_bit_writer_init_fill (GstBitWriter * bitwriter, guint8 * data, guint bits);
void
gst_bit_writer_clear (GstBitWriter * bitwriter, gboolean free_data);
guint
gst_bit_writer_get_size (GstBitWriter * bitwriter);
guint8 *
gst_bit_writer_get_data (GstBitWriter * bitwriter);
gboolean
gst_bit_writer_set_pos (GstBitWriter * bitwriter, guint pos);
guint
gst_bit_writer_get_space (GstBitWriter * bitwriter);
gboolean
gst_bit_writer_put_bits_uint8 (GstBitWriter * bitwriter,
guint8 value, guint nbits);
gboolean
gst_bit_writer_put_bits_uint16 (GstBitWriter * bitwriter,
guint16 value, guint nbits);
gboolean
gst_bit_writer_put_bits_uint32 (GstBitWriter * bitwriter,
guint32 value, guint nbits);
gboolean
gst_bit_writer_put_bits_uint64 (GstBitWriter * bitwriter,
guint64 value, guint nbits);
gboolean
gst_bit_writer_put_bytes (GstBitWriter * bitwriter, const guint8 * data,
guint nbytes);
gboolean
gst_bit_writer_align_bytes (GstBitWriter * bitwriter, guint8 trailing_bit);
static const guint8 _gst_bit_writer_bit_filling_mask[9] = {
0x00, 0x01, 0x03, 0x07,
0x0F, 0x1F, 0x3F, 0x7F,
0xFF
};
/* Aligned to 256 bytes */
#define __GST_BITS_WRITER_ALIGNMENT_MASK 2047
#define __GST_BITS_WRITER_ALIGNED(bitsize) \
(((bitsize) + __GST_BITS_WRITER_ALIGNMENT_MASK)&(~__GST_BITS_WRITER_ALIGNMENT_MASK))
static inline gboolean
_gst_bit_writer_check_space (GstBitWriter * bitwriter, guint32 bits)
{
guint32 new_bit_size = bits + bitwriter->bit_size;
guint32 clear_pos;
g_assert (bitwriter->bit_size <= bitwriter->bit_capacity);
if (new_bit_size <= bitwriter->bit_capacity)
return TRUE;
if (!bitwriter->auto_grow)
return FALSE;
/* auto grow space */
new_bit_size = __GST_BITS_WRITER_ALIGNED (new_bit_size);
g_assert (new_bit_size
&& ((new_bit_size & __GST_BITS_WRITER_ALIGNMENT_MASK) == 0));
clear_pos = ((bitwriter->bit_size + 7) >> 3);
bitwriter->data = g_realloc (bitwriter->data, (new_bit_size >> 3));
memset (bitwriter->data + clear_pos, 0, (new_bit_size >> 3) - clear_pos);
bitwriter->bit_capacity = new_bit_size;
return TRUE;
}
#undef __GST_BITS_WRITER_ALIGNMENT_MASK
#undef __GST_BITS_WRITER_ALIGNED
#define __GST_BIT_WRITER_WRITE_BITS_UNCHECKED(bits) \
static inline void \
gst_bit_writer_put_bits_uint##bits##_unchecked( \
GstBitWriter *bitwriter, \
guint##bits value, \
guint nbits \
) \
{ \
guint byte_pos, bit_offset; \
guint8 *cur_byte; \
guint fill_bits; \
\
byte_pos = (bitwriter->bit_size >> 3); \
bit_offset = (bitwriter->bit_size & 0x07); \
cur_byte = bitwriter->data + byte_pos; \
g_assert (nbits <= bits); \
g_assert( bit_offset < 8 && \
bitwriter->bit_size <= bitwriter->bit_capacity); \
\
while (nbits) { \
fill_bits = ((8 - bit_offset) < nbits ? (8 - bit_offset) : nbits); \
nbits -= fill_bits; \
bitwriter->bit_size += fill_bits; \
\
*cur_byte |= (((value >> nbits) & _gst_bit_writer_bit_filling_mask[fill_bits]) \
<< (8 - bit_offset - fill_bits)); \
++cur_byte; \
bit_offset = 0; \
} \
g_assert(cur_byte <= \
(bitwriter->data + (bitwriter->bit_capacity >> 3))); \
}
__GST_BIT_WRITER_WRITE_BITS_UNCHECKED (8)
__GST_BIT_WRITER_WRITE_BITS_UNCHECKED (16)
__GST_BIT_WRITER_WRITE_BITS_UNCHECKED (32)
__GST_BIT_WRITER_WRITE_BITS_UNCHECKED (64)
#undef __GST_BIT_WRITER_WRITE_BITS_UNCHECKED
static inline guint
gst_bit_writer_get_size_unchecked (GstBitWriter * bitwriter)
{
return GST_BIT_WRITER_BIT_SIZE (bitwriter);
}
static inline guint8 *
gst_bit_writer_get_data_unchecked (GstBitWriter * bitwriter)
{
return GST_BIT_WRITER_DATA (bitwriter);
}
static inline gboolean
gst_bit_writer_set_pos_unchecked (GstBitWriter * bitwriter, guint pos)
{
GST_BIT_WRITER_BIT_SIZE (bitwriter) = pos;
return TRUE;
}
static inline guint
gst_bit_writer_get_space_unchecked (GstBitWriter * bitwriter)
{
return bitwriter->bit_capacity - bitwriter->bit_size;
}
static inline void
gst_bit_writer_put_bytes_unchecked (GstBitWriter * bitwriter,
const guint8 * data, guint nbytes)
{
if ((bitwriter->bit_size & 0x07) == 0) {
memcpy (&bitwriter->data[bitwriter->bit_size >> 3], data, nbytes);
bitwriter->bit_size += (nbytes << 3);
} else {
g_assert (0);
while (nbytes) {
gst_bit_writer_put_bits_uint8_unchecked (bitwriter, *data, 8);
--nbytes;
++data;
}
}
}
static inline void
gst_bit_writer_align_bytes_unchecked (GstBitWriter * bitwriter,
guint8 trailing_bit)
{
guint32 bit_offset, bit_left;
guint8 value = 0;
bit_offset = (bitwriter->bit_size & 0x07);
if (!bit_offset)
return;
bit_left = 8 - bit_offset;
if (trailing_bit)
value = _gst_bit_writer_bit_filling_mask[bit_left];
return gst_bit_writer_put_bits_uint8_unchecked (bitwriter, value, bit_left);
}
#define __GST_BIT_WRITER_WRITE_BITS_INLINE(bits) \
static inline gboolean \
_gst_bit_writer_put_bits_uint##bits##_inline( \
GstBitWriter *bitwriter, \
guint##bits value, \
guint nbits \
) \
{ \
g_return_val_if_fail(bitwriter != NULL, FALSE); \
g_return_val_if_fail(nbits != 0, FALSE); \
g_return_val_if_fail(nbits <= bits, FALSE); \
\
if (!_gst_bit_writer_check_space(bitwriter, nbits)) \
return FALSE; \
gst_bit_writer_put_bits_uint##bits##_unchecked(bitwriter, value, nbits); \
return TRUE; \
}
__GST_BIT_WRITER_WRITE_BITS_INLINE (8)
__GST_BIT_WRITER_WRITE_BITS_INLINE (16)
__GST_BIT_WRITER_WRITE_BITS_INLINE (32)
__GST_BIT_WRITER_WRITE_BITS_INLINE (64)
#undef __GST_BIT_WRITER_WRITE_BITS_INLINE
static inline guint
_gst_bit_writer_get_size_inline (GstBitWriter * bitwriter)
{
g_return_val_if_fail (bitwriter != NULL, 0);
return gst_bit_writer_get_size_unchecked (bitwriter);
}
static inline guint8 *
_gst_bit_writer_get_data_inline (GstBitWriter * bitwriter)
{
g_return_val_if_fail (bitwriter != NULL, NULL);
return gst_bit_writer_get_data_unchecked (bitwriter);
}
static inline gboolean
_gst_bit_writer_set_pos_inline (GstBitWriter * bitwriter, guint pos)
{
g_return_val_if_fail (bitwriter != NULL, FALSE);
g_return_val_if_fail (pos <= bitwriter->bit_capacity, FALSE);
return gst_bit_writer_set_pos_unchecked (bitwriter, pos);
}
static inline guint
_gst_bit_writer_get_space_inline (GstBitWriter * bitwriter)
{
g_return_val_if_fail (bitwriter != NULL, 0);
g_return_val_if_fail (bitwriter->bit_size < bitwriter->bit_capacity, 0);
return gst_bit_writer_get_space_unchecked (bitwriter);
}
static inline gboolean
_gst_bit_writer_put_bytes_inline (GstBitWriter * bitwriter,
const guint8 * data, guint nbytes)
{
g_return_val_if_fail (bitwriter != NULL, FALSE);
g_return_val_if_fail (data != NULL, FALSE);
g_return_val_if_fail (nbytes, FALSE);
if (!_gst_bit_writer_check_space (bitwriter, nbytes * 8))
return FALSE;
gst_bit_writer_put_bytes_unchecked (bitwriter, data, nbytes);
return TRUE;
}
static inline gboolean
_gst_bit_writer_align_bytes_inline (GstBitWriter * bitwriter,
guint8 trailing_bit)
{
g_return_val_if_fail (bitwriter != NULL, FALSE);
g_return_val_if_fail ((trailing_bit == 0 || trailing_bit == 1), FALSE);
g_return_val_if_fail (((bitwriter->bit_size + 7) & (~7)) <=
bitwriter->bit_capacity, FALSE);
gst_bit_writer_align_bytes_unchecked (bitwriter, trailing_bit);
return TRUE;
}
#ifndef GST_BIT_WRITER_DISABLE_INLINES
#define gst_bit_writer_get_size(bitwriter) \
_gst_bit_writer_get_size_inline(bitwriter)
#define gst_bit_writer_get_data(bitwriter) \
_gst_bit_writer_get_data_inline(bitwriter)
#define gst_bit_writer_set_pos(bitwriter, pos) \
G_LIKELY (_gst_bit_writer_set_pos_inline (bitwriter, pos))
#define gst_bit_writer_get_space(bitwriter) \
_gst_bit_writer_get_space_inline(bitwriter)
#define gst_bit_writer_put_bits_uint8(bitwriter, value, nbits) \
G_LIKELY (_gst_bit_writer_put_bits_uint8_inline (bitwriter, value, nbits))
#define gst_bit_writer_put_bits_uint16(bitwriter, value, nbits) \
G_LIKELY (_gst_bit_writer_put_bits_uint16_inline (bitwriter, value, nbits))
#define gst_bit_writer_put_bits_uint32(bitwriter, value, nbits) \
G_LIKELY (_gst_bit_writer_put_bits_uint32_inline (bitwriter, value, nbits))
#define gst_bit_writer_put_bits_uint64(bitwriter, value, nbits) \
G_LIKELY (_gst_bit_writer_put_bits_uint64_inline (bitwriter, value, nbits))
#define gst_bit_writer_put_bytes(bitwriter, data, nbytes) \
G_LIKELY (_gst_bit_writer_put_bytes_inline (bitwriter, data, nbytes))
#define gst_bit_writer_align_bytes(bitwriter, trailing_bit) \
G_LIKELY (_gst_bit_writer_align_bytes_inline(bitwriter, trailing_bit))
#endif
G_END_DECLS
#endif /* GST_BIT_WRITER_H */