/src/libmpeg2/decoder/impeg2d_bitstream.c

Source
/******************************************************************************
 *
 * 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 Name         : impeg2d_bitstream.c                                  */
/*                                                                           */
/*  Description       : This file contains all the necessary examples to     */
/*                      establish a consistent use of Ittiam C coding        */
/*                      standards (based on Indian Hill C Standards)         */
/*                                                                           */
/*  List of Functions : <List the functions defined in this file>            */
/*                                                                           */
/*  Issues / Problems : None                                                 */
/*                                                                           */
/*  Revision History  :                                                      */
/*                                                                           */
/*         DD MM YYYY   Author(s)       Changes (Describe the changes made)  */
/*         10 01 2005   Ittiam          Draft                                */
/*                                                                           */
/*****************************************************************************/
#include <stdlib.h>

#include "iv_datatypedef.h"
#include "impeg2_defs.h"
#include "impeg2_platform_macros.h"
#include "impeg2_macros.h"
#include "impeg2d_bitstream.h"

#define BIT(val,bit)      (UWORD16)(((val) >> (bit)) & 0x1)
/******************************************************************************
*
*  Function Name    : impeg2d_bit_stream_init
*
*  Description      : This is a Bitstream initialising function.
*  Arguments        :
*  stream           : Pointer to the Bitstream.
*  byteBuf          : Address of the buffer
*  size             : Size of the buffer in bytes
*
*  Values Returned  : None
*******************************************************************************/
void impeg2d_bit_stream_init(stream_t *ps_stream,
                             UWORD8 *pu1_byte_buf,
                             UWORD32 u4_max_offset)
{
    UWORD8      *pu1_byte_buff;
    UWORD32     *pu4_word_buf;
    size_t     u4_byte_addr;
    UWORD32     u4_temp1,u4_temp2;

    /* Set parameters of the stream structure.Associate the structure with
       the file */
    ps_stream->pv_bs_buf           = pu1_byte_buf;
    ps_stream->u4_offset              = 0;

    /* Take care of unaligned address and create
       nearest greater aligned address */
    pu1_byte_buff               = (UWORD8 *)pu1_byte_buf;
    u4_byte_addr                = (size_t)pu1_byte_buff;

    if((u4_byte_addr & 3) == 1)
    {
        u4_temp1                = ((UWORD32)(*pu1_byte_buff++)) << 8;
        u4_temp1                += ((UWORD32)(*pu1_byte_buff++)) << 16;
        u4_temp1                += ((UWORD32)(*pu1_byte_buff++)) << 24;

        pu4_word_buf            = (UWORD32 *)pu1_byte_buff;

        ps_stream->u4_offset          = 8;
    }
    else if((u4_byte_addr & 3) == 2)
    {
        u4_temp1                = ((UWORD32)(*pu1_byte_buff++)) << 16;
        u4_temp1                += ((UWORD32)(*pu1_byte_buff++)) << 24;

        pu4_word_buf            = (UWORD32 *)pu1_byte_buff;

        ps_stream->u4_offset          = 16;
    }
    else if((u4_byte_addr & 3) == 3)
    {
        u4_temp1                = (((UWORD32)(*pu1_byte_buff++)) << 24);

        pu4_word_buf            = (UWORD32 *)pu1_byte_buff;

        ps_stream->u4_offset          = 24;
    }
    else
    {
        pu4_word_buf            = (UWORD32 *)pu1_byte_buff;

        u4_temp1                = *pu4_word_buf++;
        ps_stream->u4_offset          = 0;
    }

    /* convert the endian ness from Little endian to Big endian so that bits
       are in proper order from MSB to LSB */
    CONV_LE_TO_BE(u4_temp2,u4_temp1)

    /* Read One more word for buf nxt */
    u4_temp1                    = *pu4_word_buf++;
    ps_stream->u4_buf              = u4_temp2;

    CONV_LE_TO_BE(u4_temp2,u4_temp1)

    ps_stream->u4_buf_nxt          = u4_temp2;

    ps_stream->pu4_buf_aligned      = pu4_word_buf;


    ps_stream->u4_max_offset        = (u4_max_offset << 3) + ps_stream->u4_offset;

    return;
}



/******************************************************************************
*
*  Function Name    : impeg2d_bit_stream_get_bit
*
*  Description      : 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.
*  Arguments        :
*  stream           : Pointer to the Bitstream.
*
*  Values Returned  : The bit read(0/1)
*******************************************************************************/
UWORD8 impeg2d_bit_stream_get_bit(stream_t *ps_stream)
{
    UWORD32     u4_bit,u4_offset,u4_temp;
    UWORD32     u4_curr_bit;

    u4_offset               = ps_stream->u4_offset;
    u4_curr_bit             = u4_offset & 0x1F;
    u4_bit                  = ps_stream->u4_buf;

    /* Move the current bit read from the current word to the
       least significant bit positions of 'c'.*/
    u4_bit                  >>= BITS_IN_INT - u4_curr_bit - 1;

    u4_offset++;

    /* If the last bit of the last word of the buffer has been read update
       the currrent buf with next, and read next buf from bit stream buffer */
    if (u4_curr_bit == 31)
    {
        ps_stream->u4_buf      = ps_stream->u4_buf_nxt;

        if (ps_stream->u4_offset < ps_stream->u4_max_offset)
        {
            u4_temp             = *(ps_stream->pu4_buf_aligned)++;
            CONV_LE_TO_BE(ps_stream->u4_buf_nxt,u4_temp)
        }
    }
    ps_stream->u4_offset          = u4_offset;

    return (u4_bit & 0x1);
}
/******************************************************************************
*
*  Function Name    : impeg2d_bit_stream_flush
*
*  Description      : This is a Bitstream processing function. It
*                     advances the bit and byte pointers appropriately
*
*  Arguments        :
*  ctxt             : Pointer to the Bitstream.
*  numBits          : No of bits to be read
*
*  Values Returned  : None
*******************************************************************************/
void impeg2d_bit_stream_flush(void* pv_ctxt, UWORD32 u4_no_of_bits)
{
    stream_t *ps_stream = (stream_t *)pv_ctxt;


    if (ps_stream->u4_offset <= ps_stream->u4_max_offset)
    {
        /* We have to flush the bytes even if the offset is equal to the maximum
         * offset. This will ensure that a stream with an error exactly at the
         * offset will not get stuck in an infinite loop - If we do not flush
         * these bytes, then we keep feeding the erroneous bits.
         */
        FLUSH_BITS(ps_stream->u4_offset,ps_stream->u4_buf,ps_stream->u4_buf_nxt,u4_no_of_bits,ps_stream->pu4_buf_aligned)
    }
    return;
}
/******************************************************************************
*
*  Function Name    : impeg2d_bit_stream_flush_to_byte_boundary
*
*  Description      : This is a Bitstream processing function.It advances
*                     the bit and byte pointers to next byte boundary
*
*  Arguments        :
*  stream           : Pointer to the Bitstream.
*  NoOfBits         : No of bits to be read
*
*  Values Returned  : The bits read (upto 32 bits maximum) starting from the
*                     least significant bit and going towards most significant
*                     bit in the order of their occurence.
*******************************************************************************/
void impeg2d_bit_stream_flush_to_byte_boundary(void* pv_ctxt)
{
    UWORD8 u1_bit_offset;
    stream_t *ps_stream = (stream_t *)pv_ctxt;

    u1_bit_offset = (ps_stream->u4_offset) & 0x7;


    /* if it is not byte aligned make it byte aligned*/
    if(u1_bit_offset != 0)
    {
        impeg2d_bit_stream_flush(ps_stream,(8 - u1_bit_offset));
    }



}


/******************************************************************************
*
*  Function Name    : ibits_next
*
*  Description      : This is a Bitstream processing function.It gets the
*                     specified number of bits from the buffer without
*                     altering the current pointers. It is used mainly to
*                     check for some specific pattern of bits like start
*                     code. This is equivalent to next_bits() function
*                     defined in MPEG-4 Visual Standard Definition of functions
*
*  Arguments        :
*  ctxt             : Pointer to the Bitstream.
*  numBits          : No of bits to be read
*
*  Values Returned  : The bits read (upto 32 bits maximum) starting from the
*                     least significant bit and going towards most significant
*                     bit in the order of their occurence.
*******************************************************************************/
UWORD32 impeg2d_bit_stream_nxt( stream_t  *ps_stream, WORD32 i4_no_of_bits)
{
    UWORD32     u4_bits,u4_offset,u4_temp;
    UWORD8      u4_bit_ptr;

    ASSERT(i4_no_of_bits > 0);

    u4_offset               = ps_stream->u4_offset;
    u4_bit_ptr              = u4_offset & 0x1F;
    u4_bits                 = ps_stream->u4_buf << u4_bit_ptr;

    u4_bit_ptr              += i4_no_of_bits;
    if(32 < u4_bit_ptr)
    {
        /*  Read bits from the next word if necessary */
        u4_temp             = ps_stream->u4_buf_nxt;
        u4_bit_ptr          &= (BITS_IN_INT - 1);

        u4_temp             = (u4_temp >> (BITS_IN_INT - u4_bit_ptr));

        /* u4_temp consists of bits,if any that had to be read from the next word
           of the buffer.The bits read from both the words are concatenated and
           moved to the least significant positions of 'u4_bits'*/
        u4_bits = (u4_bits >> (32 - i4_no_of_bits)) | u4_temp;
    }
    else
    {
        u4_bits = (u4_bits >> (32 - i4_no_of_bits));
    }

    return (u4_bits);
}
/******************************************************************************
*
*  Function Name    : impeg2d_bit_stream_get
*
*  Description      : This is a Bitstream processing function. It reads a
*                     specified number of bits from the current bit
*                     position and advances the bit and byte pointers
*                     appropriately
*  Arguments        :
*  ctxt             : Pointer to the Bitstream.
*  numBits          : No of bits to be read
*
*  Values Returned  : The bits read (upto 32 bits maximum) starting from the
*                     least significant bit and going towards most significant
*                     bit in the order of their occurence.
*******************************************************************************/

UWORD32 impeg2d_bit_stream_get(void* pv_ctxt, UWORD32 u4_num_bits)
{
    UWORD32 u4_next_bits = impeg2d_bit_stream_nxt(pv_ctxt, u4_num_bits);
    impeg2d_bit_stream_flush(pv_ctxt, u4_num_bits);
    return(u4_next_bits);
}



/******************************************************************************
*
*  Function Name    : impeg2d_bit_stream_num_bits_read
*
*  Description      : This is a Bitstream processing function. It reads a
*                     specified number of bits from the current bit
*                     position and advances the bit and byte pointers
*                     appropriately
*  Arguments        :
*  ctxt             : Pointer to the Bitstream.
*  numBits          : No of bits to be read
*
*  Values Returned  : The bits read (upto 16 bits maximum) starting from the
*                     least significant bit and going towards most significant
*                     bit in the order of their occurence.
*******************************************************************************/
UWORD32 impeg2d_bit_stream_num_bits_read(void* pv_ctxt)
{
    stream_t *u4_no_of_bitsstream = (stream_t *)pv_ctxt;
    size_t     u4_temp;
    UWORD32     u4_bits_read;
    u4_temp         = (size_t)(u4_no_of_bitsstream->pv_bs_buf);
    u4_temp         &= 0x3;
    u4_bits_read         = (u4_no_of_bitsstream->u4_offset - (u4_temp << 3));

    return(u4_bits_read);

}



Coverage Report

Created: 2026-06-10 06:54

Line	Count	Source
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		/* File Name : impeg2d_bitstream.c */
23		/* */
24		/* Description : This file contains all the necessary examples to */
25		/* establish a consistent use of Ittiam C coding */
26		/* standards (based on Indian Hill C Standards) */
27		/* */
28		/* List of Functions : <List the functions defined in this file> */
29		/* */
30		/* Issues / Problems : None */
31		/* */
32		/* Revision History : */
33		/* */
34		/* DD MM YYYY Author(s) Changes (Describe the changes made) */
35		/* 10 01 2005 Ittiam Draft */
36		/* */
37		/*****************************************************************************/
38		#include <stdlib.h>
39
40		#include "iv_datatypedef.h"
41		#include "impeg2_defs.h"
42		#include "impeg2_platform_macros.h"
43		#include "impeg2_macros.h"
44		#include "impeg2d_bitstream.h"
45
46		#define BIT(val,bit) (UWORD16)(((val) >> (bit)) & 0x1)
47		/******************************************************************************
48		*
49		* Function Name : impeg2d_bit_stream_init
50		*
51		* Description : This is a Bitstream initialising function.
52		* Arguments :
53		* stream : Pointer to the Bitstream.
54		* byteBuf : Address of the buffer
55		* size : Size of the buffer in bytes
56		*
57		* Values Returned : None
58		*******************************************************************************/
59		void impeg2d_bit_stream_init(stream_t *ps_stream,
60		UWORD8 *pu1_byte_buf,
61		UWORD32 u4_max_offset)
62	100k	{
63	100k	UWORD8 *pu1_byte_buff;
64	100k	UWORD32 *pu4_word_buf;
65	100k	size_t u4_byte_addr;
66	100k	UWORD32 u4_temp1,u4_temp2;
67
68		/* Set parameters of the stream structure.Associate the structure with
69		the file */
70	100k	ps_stream->pv_bs_buf = pu1_byte_buf;
71	100k	ps_stream->u4_offset = 0;
72
73		/* Take care of unaligned address and create
74		nearest greater aligned address */
75	100k	pu1_byte_buff = (UWORD8 *)pu1_byte_buf;
76	100k	u4_byte_addr = (size_t)pu1_byte_buff;
77
78	100k	if((u4_byte_addr & 3) == 1)
79	7.66k	{
80	7.66k	u4_temp1 = ((UWORD32)(*pu1_byte_buff++)) << 8;
81	7.66k	u4_temp1 += ((UWORD32)(*pu1_byte_buff++)) << 16;
82	7.66k	u4_temp1 += ((UWORD32)(*pu1_byte_buff++)) << 24;
83
84	7.66k	pu4_word_buf = (UWORD32 *)pu1_byte_buff;
85
86	7.66k	ps_stream->u4_offset = 8;
87	7.66k	}
88	93.0k	else if((u4_byte_addr & 3) == 2)
89	9.61k	{
90	9.61k	u4_temp1 = ((UWORD32)(*pu1_byte_buff++)) << 16;
91	9.61k	u4_temp1 += ((UWORD32)(*pu1_byte_buff++)) << 24;
92
93	9.61k	pu4_word_buf = (UWORD32 *)pu1_byte_buff;
94
95	9.61k	ps_stream->u4_offset = 16;
96	9.61k	}
97	83.4k	else if((u4_byte_addr & 3) == 3)
98	5.93k	{
99	5.93k	u4_temp1 = (((UWORD32)(*pu1_byte_buff++)) << 24);
100
101	5.93k	pu4_word_buf = (UWORD32 *)pu1_byte_buff;
102
103	5.93k	ps_stream->u4_offset = 24;
104	5.93k	}
105	77.4k	else
106	77.4k	{
107	77.4k	pu4_word_buf = (UWORD32 *)pu1_byte_buff;
108
109	77.4k	u4_temp1 = *pu4_word_buf++;
110	77.4k	ps_stream->u4_offset = 0;
111	77.4k	}
112
113		/* convert the endian ness from Little endian to Big endian so that bits
114		are in proper order from MSB to LSB */
115	100k	CONV_LE_TO_BE(u4_temp2,u4_temp1)
116
117		/* Read One more word for buf nxt */
118	100k	u4_temp1 = *pu4_word_buf++;
119	100k	ps_stream->u4_buf = u4_temp2;
120
121	100k	CONV_LE_TO_BE(u4_temp2,u4_temp1)
122
123	100k	ps_stream->u4_buf_nxt = u4_temp2;
124
125	100k	ps_stream->pu4_buf_aligned = pu4_word_buf;
126
127
128	100k	ps_stream->u4_max_offset = (u4_max_offset << 3) + ps_stream->u4_offset;
129
130	100k	return;
131	100k	}
132
133
134
135		/******************************************************************************
136		*
137		* Function Name : impeg2d_bit_stream_get_bit
138		*
139		* Description : This is a Bitstream processing function. It reads the
140		* bit currently pointed by the bit pointer in the buffer and
141		* advances the pointer by one.
142		* Arguments :
143		* stream : Pointer to the Bitstream.
144		*
145		* Values Returned : The bit read(0/1)
146		*******************************************************************************/
147		UWORD8 impeg2d_bit_stream_get_bit(stream_t *ps_stream)
148	4.81M	{
149	4.81M	UWORD32 u4_bit,u4_offset,u4_temp;
150	4.81M	UWORD32 u4_curr_bit;
151
152	4.81M	u4_offset = ps_stream->u4_offset;
153	4.81M	u4_curr_bit = u4_offset & 0x1F;
154	4.81M	u4_bit = ps_stream->u4_buf;
155
156		/* Move the current bit read from the current word to the
157		least significant bit positions of 'c'.*/
158	4.81M	u4_bit >>= BITS_IN_INT - u4_curr_bit - 1;
159
160	4.81M	u4_offset++;
161
162		/* If the last bit of the last word of the buffer has been read update
163		the currrent buf with next, and read next buf from bit stream buffer */
164	4.81M	if (u4_curr_bit == 31)
165	305k	{
166	305k	ps_stream->u4_buf = ps_stream->u4_buf_nxt;
167
168	305k	if (ps_stream->u4_offset < ps_stream->u4_max_offset)
169	304k	{
170	304k	u4_temp = *(ps_stream->pu4_buf_aligned)++;
171	304k	CONV_LE_TO_BE(ps_stream->u4_buf_nxt,u4_temp)
172	304k	}
173	305k	}
174	4.81M	ps_stream->u4_offset = u4_offset;
175
176	4.81M	return (u4_bit & 0x1);
177	4.81M	}
178		/******************************************************************************
179		*
180		* Function Name : impeg2d_bit_stream_flush
181		*
182		* Description : This is a Bitstream processing function. It
183		* advances the bit and byte pointers appropriately
184		*
185		* Arguments :
186		* ctxt : Pointer to the Bitstream.
187		* numBits : No of bits to be read
188		*
189		* Values Returned : None
190		*******************************************************************************/
191		void impeg2d_bit_stream_flush(void* pv_ctxt, UWORD32 u4_no_of_bits)
192	970M	{
193	970M	stream_t ps_stream = (stream_t )pv_ctxt;
194
195
196	970M	if (ps_stream->u4_offset <= ps_stream->u4_max_offset)
197	970M	{
198		/* We have to flush the bytes even if the offset is equal to the maximum
199		* offset. This will ensure that a stream with an error exactly at the
200		* offset will not get stuck in an infinite loop - If we do not flush
201		* these bytes, then we keep feeding the erroneous bits.
202		*/
203	970M	FLUSH_BITS(ps_stream->u4_offset,ps_stream->u4_buf,ps_stream->u4_buf_nxt,u4_no_of_bits,ps_stream->pu4_buf_aligned)
204	970M	}
205	970M	return;
206	970M	}
207		/******************************************************************************
208		*
209		* Function Name : impeg2d_bit_stream_flush_to_byte_boundary
210		*
211		* Description : This is a Bitstream processing function.It advances
212		* the bit and byte pointers to next byte boundary
213		*
214		* Arguments :
215		* stream : Pointer to the Bitstream.
216		* NoOfBits : No of bits to be read
217		*
218		* Values Returned : The bits read (upto 32 bits maximum) starting from the
219		* least significant bit and going towards most significant
220		* bit in the order of their occurence.
221		*******************************************************************************/
222		void impeg2d_bit_stream_flush_to_byte_boundary(void* pv_ctxt)
223	5.83M	{
224	5.83M	UWORD8 u1_bit_offset;
225	5.83M	stream_t ps_stream = (stream_t )pv_ctxt;
226
227	5.83M	u1_bit_offset = (ps_stream->u4_offset) & 0x7;
228
229
230		/* if it is not byte aligned make it byte aligned*/
231	5.83M	if(u1_bit_offset != 0)
232	4.21M	{
233	4.21M	impeg2d_bit_stream_flush(ps_stream,(8 - u1_bit_offset));
234	4.21M	}
235
236
237
238	5.83M	}
239
240
241		/******************************************************************************
242		*
243		* Function Name : ibits_next
244		*
245		* Description : This is a Bitstream processing function.It gets the
246		* specified number of bits from the buffer without
247		* altering the current pointers. It is used mainly to
248		* check for some specific pattern of bits like start
249		* code. This is equivalent to next_bits() function
250		* defined in MPEG-4 Visual Standard Definition of functions
251		*
252		* Arguments :
253		* ctxt : Pointer to the Bitstream.
254		* numBits : No of bits to be read
255		*
256		* Values Returned : The bits read (upto 32 bits maximum) starting from the
257		* least significant bit and going towards most significant
258		* bit in the order of their occurence.
259		*******************************************************************************/
260		UWORD32 impeg2d_bit_stream_nxt( stream_t *ps_stream, WORD32 i4_no_of_bits)
261	1.35G	{
262	1.35G	UWORD32 u4_bits,u4_offset,u4_temp;
263	1.35G	UWORD8 u4_bit_ptr;
264
265	1.35G	ASSERT(i4_no_of_bits > 0);
266
267	1.35G	u4_offset = ps_stream->u4_offset;
268	1.35G	u4_bit_ptr = u4_offset & 0x1F;
269	1.35G	u4_bits = ps_stream->u4_buf << u4_bit_ptr;
270
271	1.35G	u4_bit_ptr += i4_no_of_bits;
272	1.35G	if(32 < u4_bit_ptr)
273	371M	{
274		/* Read bits from the next word if necessary */
275	371M	u4_temp = ps_stream->u4_buf_nxt;
276	371M	u4_bit_ptr &= (BITS_IN_INT - 1);
277
278	371M	u4_temp = (u4_temp >> (BITS_IN_INT - u4_bit_ptr));
279
280		/* u4_temp consists of bits,if any that had to be read from the next word
281		of the buffer.The bits read from both the words are concatenated and
282		moved to the least significant positions of 'u4_bits'*/
283	371M	u4_bits = (u4_bits >> (32 - i4_no_of_bits)) \| u4_temp;
284	371M	}
285	982M	else
286	982M	{
287	982M	u4_bits = (u4_bits >> (32 - i4_no_of_bits));
288	982M	}
289
290	1.35G	return (u4_bits);
291	1.35G	}
292		/******************************************************************************
293		*
294		* Function Name : impeg2d_bit_stream_get
295		*
296		* Description : This is a Bitstream processing function. It reads a
297		* specified number of bits from the current bit
298		* position and advances the bit and byte pointers
299		* appropriately
300		* Arguments :
301		* ctxt : Pointer to the Bitstream.
302		* numBits : No of bits to be read
303		*
304		* Values Returned : The bits read (upto 32 bits maximum) starting from the
305		* least significant bit and going towards most significant
306		* bit in the order of their occurence.
307		*******************************************************************************/
308
309		UWORD32 impeg2d_bit_stream_get(void* pv_ctxt, UWORD32 u4_num_bits)
310	609M	{
311	609M	UWORD32 u4_next_bits = impeg2d_bit_stream_nxt(pv_ctxt, u4_num_bits);
312	609M	impeg2d_bit_stream_flush(pv_ctxt, u4_num_bits);
313	609M	return(u4_next_bits);
314	609M	}
315
316
317
318		/******************************************************************************
319		*
320		* Function Name : impeg2d_bit_stream_num_bits_read
321		*
322		* Description : This is a Bitstream processing function. It reads a
323		* specified number of bits from the current bit
324		* position and advances the bit and byte pointers
325		* appropriately
326		* Arguments :
327		* ctxt : Pointer to the Bitstream.
328		* numBits : No of bits to be read
329		*
330		* Values Returned : The bits read (upto 16 bits maximum) starting from the
331		* least significant bit and going towards most significant
332		* bit in the order of their occurence.
333		*******************************************************************************/
334		UWORD32 impeg2d_bit_stream_num_bits_read(void* pv_ctxt)
335	19.1k	{
336	19.1k	stream_t u4_no_of_bitsstream = (stream_t )pv_ctxt;
337	19.1k	size_t u4_temp;
338	19.1k	UWORD32 u4_bits_read;
339	19.1k	u4_temp = (size_t)(u4_no_of_bitsstream->pv_bs_buf);
340	19.1k	u4_temp &= 0x3;
341	19.1k	u4_bits_read = (u4_no_of_bitsstream->u4_offset - (u4_temp << 3));
342
343	19.1k	return(u4_bits_read);
344
345	19.1k	}
346
347