xref: /aosp_15_r20/external/libavc/decoder/ih264d_bitstrm.h (revision 495ae853bb871d1e5a258cb02c2cc13cde8ddb9a)

/******************************************************************************
 *
 * 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
*/

#ifndef _IH264D_BITSTRM_H_
#define _IH264D_BITSTRM_H_
/*!
 *************************************************************************
 * \file ih264d_bitstrm.h
 *
 * \brief
 *  Contains all the declarations of bitstream reading routines
 *
 * \date
 *    20/11/2002
 *
 * \author  AI
 *************************************************************************
 */

/* Includes */
#include <stdio.h>
#include <stdlib.h>
#include "ih264_typedefs.h"
#include "ih264_macros.h"
#include "ih264_platform_macros.h"

#define INT_IN_BYTES        4
#define INT_IN_BITS         32

/* Based on level 1.2 of baseline profile */
/* 396[MAX_FS] * 128 * 1.5 [ChromaFormatParameter] / sizeof(UWORD32)
 i.e  396 * 128 * 1.5 / 4 = 19008 */
/* Based on level 3 of main profile */
/* 1620[MAX_FS] * 128 * 1.5 [ChromaFormatParameter] / sizeof(UWORD32)
 i.e  1620 * 128 * 1.5 / 4= 77760 */
#define SIZE_OF_BUFFER      77760

/* Structure for the ps_bitstrm */
typedef struct
{
    UWORD32 u4_ofst; /* Offset in the buffer for the current bit */
    UWORD32 *pu4_buffer; /* Bitstream Buffer  */
    UWORD32 u4_max_ofst; /* points to first bit beyond the buffer */
    void * pv_codec_handle; /* For Error Handling */
} dec_bit_stream_t;

/* To read the next bit */
UWORD8 ih264d_get_bit_h264(dec_bit_stream_t *);

/* To read the next specified number of bits */
UWORD32 ih264d_get_bits_h264(dec_bit_stream_t *, UWORD32);

/* To see the next specified number of bits */
UWORD32 ih264d_next_bits_h264(dec_bit_stream_t *, UWORD32);

/* To flush a specified number of bits*/
WORD32 ih264d_flush_bits_h264(dec_bit_stream_t *, WORD32);

/*!
 **************************************************************************
 * \if Function name : MoreRbspData \endif
 *
 * \brief
 *    Determines whether there is more data in RBSP or not.
 *
 * \param ps_bitstrm : Pointer to bitstream
 *
 * \return
 *    Returns 1 if there is more data in RBSP before rbsp_trailing_bits().
 *    Otherwise it returns FALSE.
 **************************************************************************
 */


#define EXCEED_OFFSET(ps_bitstrm) \
  (ps_bitstrm->u4_ofst > ps_bitstrm->u4_max_ofst)
#define CHECK_BITS_SUFFICIENT(ps_bitstrm, bits_to_read) \
  (ps_bitstrm->u4_ofst + bits_to_read <= ps_bitstrm->u4_max_ofst)
#define MORE_RBSP_DATA(ps_bitstrm) \
    CHECK_BITS_SUFFICIENT(ps_bitstrm, 1)

void GoToByteBoundary(dec_bit_stream_t * ps_bitstrm);
UWORD8 ih264d_check_byte_aligned(dec_bit_stream_t * ps_bitstrm);

/*****************************************************************************/
/* Define a macro for inlining of GETBIT:                                    */
/*****************************************************************************/
#define   GETBIT(u4_code, u4_offset, pu4_bitstream)                         \
{                                                                           \
    UWORD32 *pu4_buf =  (pu4_bitstream);                                    \
    UWORD32 u4_word_off = ((u4_offset) >> 5);                               \
    UWORD32 u4_bit_off = (u4_offset) & 0x1F;                                \
    u4_code = pu4_buf[u4_word_off] << u4_bit_off;                           \
    (u4_offset)++;                                                          \
    u4_code = (u4_code >> 31);                                              \
}



/*****************************************************************************/
/* Define a macro for inlining of GETBITS: u4_no_bits shall not exceed 32    */
/*****************************************************************************/
#define     GETBITS(u4_code, u4_offset, pu4_bitstream, u4_no_bits)          \
{                                                                           \
    UWORD32 *pu4_buf =  (pu4_bitstream);                                    \
    UWORD32 u4_word_off = ((u4_offset) >> 5);                               \
    UWORD32 u4_bit_off = (u4_offset) & 0x1F;                                \
    u4_code = pu4_buf[u4_word_off++] << u4_bit_off;                         \
                                                                            \
    if(u4_bit_off)                                                          \
        u4_code |= (pu4_buf[u4_word_off] >> (INT_IN_BITS - u4_bit_off));    \
    u4_code = u4_code >> (INT_IN_BITS - u4_no_bits);                        \
    (u4_offset) += u4_no_bits;                                              \
}                                                                           \
                                                                            \

/*****************************************************************************/
/* Define a macro for inlining of NEXTBITS                                   */
/*****************************************************************************/
#define     NEXTBITS(u4_word, u4_offset, pu4_bitstream, u4_no_bits)         \
{                                                                           \
    UWORD32 *pu4_buf =  (pu4_bitstream);                                    \
    UWORD32 u4_word_off = ((u4_offset) >> 5);                               \
    UWORD32 u4_bit_off = (u4_offset) & 0x1F;                                \
    u4_word = pu4_buf[u4_word_off++] << u4_bit_off;                         \
    if(u4_bit_off)                                                          \
        u4_word |= (pu4_buf[u4_word_off] >> (INT_IN_BITS - u4_bit_off));    \
    u4_word = u4_word >> (INT_IN_BITS - u4_no_bits);                        \
}
/*****************************************************************************/
/* Define a macro for inlining of NEXTBITS_32                                */
/*****************************************************************************/
#define     NEXTBITS_32(u4_word, u4_offset, pu4_bitstream)                  \
{                                                                           \
    UWORD32 *pu4_buf =  (pu4_bitstream);                                    \
    UWORD32 u4_word_off = ((u4_offset) >> 5);                               \
    UWORD32 u4_bit_off = (u4_offset) & 0x1F;                                \
                                                                            \
    u4_word = pu4_buf[u4_word_off++] << u4_bit_off;                         \
    if(u4_bit_off)                                                          \
    u4_word |= (pu4_buf[u4_word_off] >> (INT_IN_BITS - u4_bit_off));        \
}


/*****************************************************************************/
/* Define a macro for inlining of FIND_ONE_IN_STREAM_32                      */
/*****************************************************************************/
#define   FIND_ONE_IN_STREAM_32(u4_ldz, u4_offset, pu4_bitstream)           \
{                                                                           \
    UWORD32 u4_word;                                                        \
    NEXTBITS_32(u4_word, u4_offset, pu4_bitstream);                         \
    u4_ldz = CLZ(u4_word);                                     \
    (u4_offset) += (u4_ldz + 1);                                            \
}

/*****************************************************************************/
/* Define a macro for inlining of FIND_ONE_IN_STREAM_LEN                     */
/*****************************************************************************/
#define   FIND_ONE_IN_STREAM_LEN(u4_ldz, u4_offset, pu4_bitstream, u4_len)  \
{                                                                           \
    UWORD32 u4_word;                                                        \
    NEXTBITS_32(u4_word, u4_offset, pu4_bitstream);                         \
    u4_ldz = CLZ(u4_word);                                     \
    if(u4_ldz < u4_len)                                                     \
    (u4_offset) += (u4_ldz + 1);                                            \
    else                                                                    \
    {                                                                       \
        u4_ldz = u4_len;                                                    \
        (u4_offset) += u4_ldz;                                              \
    }                                                                       \
}

/*****************************************************************************/
/* Define a macro for inlining of FLUSHBITS                                  */
/*****************************************************************************/
#define   FLUSHBITS(u4_offset, u4_no_bits)                                  \
{                                                                           \
        (u4_offset) += (u4_no_bits);                                        \
}

#endif  /* _BITSTREAM_H_ */