/src/libavc/decoder/ih264d_bitstrm.c

Source (jump to first uncovered line)
/******************************************************************************
 *
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 *****************************************************************************
 * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore
*/

/*!
 **************************************************************************
 * \file ih264d_bitstrm.c
 *
 * \brief
 *    Bitstream parsing routines
 *
 * \date
 *    20/11/2002
 *
 * \author  AI
 **************************************************************************
 */

#include <stdlib.h>
#include "ih264_typedefs.h"
#include "ih264_macros.h"
#include "ih264_platform_macros.h"
#include "ih264d_bitstrm.h"
#include "ih264d_error_handler.h"

#include "ih264d_debug.h"
#include "ih264d_tables.h"
#include "ih264d_structs.h"

/*!
 **************************************************************************
 * \if Function name : ih264d_get_bit_h264 \endif
 *
 * \brief
 *    Read one bit from the bitstream.
 *
 *   This is a Bitstream processing function. It reads the
 *   bit currently pointed by the bit pointer in the
 *   buffer and advances the pointer by one. It returns
 *   the bit (0 or 1) in the form of an unsigned integer.
 *
 * \return
 *    Returns the next bit (0 or 1) in the bitstream.
 *
 **************************************************************************
 */
UWORD8 ih264d_get_bit_h264(dec_bit_stream_t *ps_stream)
{
    UWORD32 u4_code;

    GETBIT(u4_code, ps_stream->u4_ofst, ps_stream->pu4_buffer);
    return (u4_code);
}

/*!
 **************************************************************************
 * \if Function name : ih264d_get_bits_h264 \endif
 *
 * \brief
 *    Read specified number of bits from the bitstream.
 *
 *   This is a Bitstream processing function. It reads the
 *   number specified number of bits from the current bit
 *   position and advances the bit and byte pointers
 *   appropriately.
 *
 * \return
 *    An unsigned 32 bit integer with its least significant bits
 *    containing the bits in order of their occurence in the bitstream.
 *
 **************************************************************************
 */

UWORD32 ih264d_get_bits_h264(dec_bit_stream_t *ps_bitstrm, UWORD32 u4_num_bits)
{
    UWORD32 u4_code = 0;
    if(u4_num_bits)
        GETBITS(u4_code, ps_bitstrm->u4_ofst, ps_bitstrm->pu4_buffer, u4_num_bits);
    return (u4_code);
}

/*!
 **************************************************************************
 * \if Function name : ih264d_next_bits_h264 \endif
 *
 * \brief
 *    Peek specified number of bits from the bitstream.
 *
 *   This is a Bitstream processing function. It gets the
 *   specified number of bits from the buffer without
 *   altering the current pointers. It is equivalent to
 *   next_bits() function in the standard.
 *
 * \return
 *    An unsigned 32 bit integer with its least significant bits
 *    containing the bits in order of their occurence in the bitstream.
 **************************************************************************
 */
UWORD32 ih264d_next_bits_h264(dec_bit_stream_t *ps_bitstrm, UWORD32 u4_num_bits)
{
    UWORD32 u4_word_off = (ps_bitstrm->u4_ofst >> 5);
    UWORD32 u4_bit_off = ps_bitstrm->u4_ofst & 0x1F;
    UWORD32 *pu4_bitstream = ps_bitstrm->pu4_buffer;
    UWORD32 u4_bits = pu4_bitstream[u4_word_off++] << u4_bit_off;

    /*************************************************************************/
    /* Test if number of bits to be read exceeds the number of bits in the   */
    /* current word. If yes, read from the next word of the buffer, The bits */
    /* from both the words are concatenated to get next 32 bits in 'u4_bits' */
    /*************************************************************************/
    if(u4_bit_off > (INT_IN_BITS - u4_num_bits))
        u4_bits |= (pu4_bitstream[u4_word_off] >> (INT_IN_BITS - u4_bit_off));

    return ((u4_bits >> (INT_IN_BITS - u4_num_bits)));
}

/*!
 **************************************************************************
 * \if Function name : ih264d_flush_bits_h264 \endif
 *
 * \brief
 *    Flush specified number of bits from the bitstream.
 *
 *   This function flushes the specified number of bits (marks
 *   as read) from the buffer.
 *
 * \return
 *     A 8 bit unsigned integer with value
 *    '1' on successful flush
 *    '0' on failure.
 *
 **************************************************************************
 */
WORD32 ih264d_flush_bits_h264(dec_bit_stream_t *ps_bitstrm, WORD32 u4_num_bits)
{
    ps_bitstrm->u4_ofst += u4_num_bits;

    if(ps_bitstrm->u4_ofst > ps_bitstrm->u4_max_ofst)
    {
        return ERROR_EOB_FLUSHBITS_T;
    }
    return OK;
}

/*!
 **************************************************************************
 * \if Function name : ih264d_check_byte_aligned \endif
 *
 * \brief
 *    Checks whether the bit ps_bitstrm u4_ofst is at byte boundary.
 *
 * \param ps_bitstrm : Pointer to bitstream
 *
 * \return
 *    Returns 1 if bit ps_bitstrm u4_ofst is at byte alligned position else zero.
 **************************************************************************
 */

UWORD8 ih264d_check_byte_aligned(dec_bit_stream_t * ps_bitstrm)
{
    if(ps_bitstrm->u4_ofst & 0x07)
        return (0);
    else
        return (1);
}

Line	Count	Source (jump to first uncovered line)
1		/******************************************************************************
2		*
3		* Copyright (C) 2015 The Android Open Source Project
4		*
5		* Licensed under the Apache License, Version 2.0 (the "License");
6		* you may not use this file except in compliance with the License.
7		* You may obtain a copy of the License at:
8		*
9		* http://www.apache.org/licenses/LICENSE-2.0
10		*
11		* Unless required by applicable law or agreed to in writing, software
12		* distributed under the License is distributed on an "AS IS" BASIS,
13		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14		* See the License for the specific language governing permissions and
15		* limitations under the License.
16		*
17		*****************************************************************************
18		* Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore
19		*/
20
21		/*!
22		**************************************************************************
23		* \file ih264d_bitstrm.c
24		*
25		* \brief
26		* Bitstream parsing routines
27		*
28		* \date
29		* 20/11/2002
30		*
31		* \author AI
32		**************************************************************************
33		*/
34
35		#include <stdlib.h>
36		#include "ih264_typedefs.h"
37		#include "ih264_macros.h"
38		#include "ih264_platform_macros.h"
39		#include "ih264d_bitstrm.h"
40		#include "ih264d_error_handler.h"
41
42		#include "ih264d_debug.h"
43		#include "ih264d_tables.h"
44		#include "ih264d_structs.h"
45
46		/*!
47		**************************************************************************
48		* \if Function name : ih264d_get_bit_h264 \endif
49		*
50		* \brief
51		* Read one bit from the bitstream.
52		*
53		* This is a Bitstream processing function. It reads the
54		* bit currently pointed by the bit pointer in the
55		* buffer and advances the pointer by one. It returns
56		* the bit (0 or 1) in the form of an unsigned integer.
57		*
58		* \return
59		* Returns the next bit (0 or 1) in the bitstream.
60		*
61		**************************************************************************
62		*/
63		UWORD8 ih264d_get_bit_h264(dec_bit_stream_t *ps_stream)
64	4.22M	{
65	4.22M	UWORD32 u4_code;
66
67	4.22M	GETBIT(u4_code, ps_stream->u4_ofst, ps_stream->pu4_buffer);
68	4.22M	return (u4_code);
69	4.22M	}
70
71		/*!
72		**************************************************************************
73		* \if Function name : ih264d_get_bits_h264 \endif
74		*
75		* \brief
76		* Read specified number of bits from the bitstream.
77		*
78		* This is a Bitstream processing function. It reads the
79		* number specified number of bits from the current bit
80		* position and advances the bit and byte pointers
81		* appropriately.
82		*
83		* \return
84		* An unsigned 32 bit integer with its least significant bits
85		* containing the bits in order of their occurence in the bitstream.
86		*
87		**************************************************************************
88		*/
89
90		UWORD32 ih264d_get_bits_h264(dec_bit_stream_t *ps_bitstrm, UWORD32 u4_num_bits)
91	4.35M	{
92	4.35M	UWORD32 u4_code = 0;
93	4.35M	if(u4_num_bits)
94	4.35M	GETBITS(u4_code, ps_bitstrm->u4_ofst, ps_bitstrm->pu4_buffer, u4_num_bits);
95	4.35M	return (u4_code);
96	4.35M	}
97
98		/*!
99		**************************************************************************
100		* \if Function name : ih264d_next_bits_h264 \endif
101		*
102		* \brief
103		* Peek specified number of bits from the bitstream.
104		*
105		* This is a Bitstream processing function. It gets the
106		* specified number of bits from the buffer without
107		* altering the current pointers. It is equivalent to
108		* next_bits() function in the standard.
109		*
110		* \return
111		* An unsigned 32 bit integer with its least significant bits
112		* containing the bits in order of their occurence in the bitstream.
113		**************************************************************************
114		*/
115		UWORD32 ih264d_next_bits_h264(dec_bit_stream_t *ps_bitstrm, UWORD32 u4_num_bits)
116	0	{
117	0	UWORD32 u4_word_off = (ps_bitstrm->u4_ofst >> 5);
118	0	UWORD32 u4_bit_off = ps_bitstrm->u4_ofst & 0x1F;
119	0	UWORD32 *pu4_bitstream = ps_bitstrm->pu4_buffer;
120	0	UWORD32 u4_bits = pu4_bitstream[u4_word_off++] << u4_bit_off;
121
122		/*************************************************************************/
123		/* Test if number of bits to be read exceeds the number of bits in the */
124		/* current word. If yes, read from the next word of the buffer, The bits */
125		/* from both the words are concatenated to get next 32 bits in 'u4_bits' */
126		/*************************************************************************/
127	0	if(u4_bit_off > (INT_IN_BITS - u4_num_bits))
128	0	u4_bits \|= (pu4_bitstream[u4_word_off] >> (INT_IN_BITS - u4_bit_off));
129
130	0	return ((u4_bits >> (INT_IN_BITS - u4_num_bits)));
131	0	}
132
133		/*!
134		**************************************************************************
135		* \if Function name : ih264d_flush_bits_h264 \endif
136		*
137		* \brief
138		* Flush specified number of bits from the bitstream.
139		*
140		* This function flushes the specified number of bits (marks
141		* as read) from the buffer.
142		*
143		* \return
144		* A 8 bit unsigned integer with value
145		* '1' on successful flush
146		* '0' on failure.
147		*
148		**************************************************************************
149		*/
150		WORD32 ih264d_flush_bits_h264(dec_bit_stream_t *ps_bitstrm, WORD32 u4_num_bits)
151	220k	{
152	220k	ps_bitstrm->u4_ofst += u4_num_bits;
153
154	220k	if(ps_bitstrm->u4_ofst > ps_bitstrm->u4_max_ofst)
155	0	{
156	0	return ERROR_EOB_FLUSHBITS_T;
157	0	}
158	220k	return OK;
159	220k	}
160
161		/*!
162		**************************************************************************
163		* \if Function name : ih264d_check_byte_aligned \endif
164		*
165		* \brief
166		* Checks whether the bit ps_bitstrm u4_ofst is at byte boundary.
167		*
168		* \param ps_bitstrm : Pointer to bitstream
169		*
170		* \return
171		* Returns 1 if bit ps_bitstrm u4_ofst is at byte alligned position else zero.
172		**************************************************************************
173		*/
174
175		UWORD8 ih264d_check_byte_aligned(dec_bit_stream_t * ps_bitstrm)
176	2.89M	{
177	2.89M	if(ps_bitstrm->u4_ofst & 0x07)
178	2.10M	return (0);
179	792k	else
180	792k	return (1);
181	2.89M	}

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Created: 2025-07-11 06:37