dec_cavlc.c

经过开源的H.264压缩算法代码

    VLC(-1, -1),
    VLC(15, 9), /* 0000 0000 1 */
    VLC(14, 9),
    VLC(13, 9), /* 0000 0001 1 */
    VLC2(12, 8),/* 0000 0010 */
    VLC2(11, 8),/* 0000 0011 */
    VLC4(10, 7),/* 0000 010 */
    VLC4(9, 7), /* 0000 011 */
    VLC8(8, 6), /* 0000 10 */
    VLC8(7, 6), /* 0000 11 */
};

static const zero_count_t total_zero_table1_1[] = 
{
    VLC2(-1, -1),
    VLC(6, 5), /* 0001 0 */
    VLC(5, 5), /* 0001 1 */
    VLC2(4, 4),/* 0010 */
    VLC2(3, 4),/* 0011 */
    VLC4(2, 3),/* 010 */
    VLC4(1, 3),/* 011 */
    VLC8(0, 1), /*1 */
    VLC8(0, 1), /*1 */
};

static const zero_count_t total_zero_table2_0[] = 
{
    VLC(14, 6), /* 0000 00 */
    VLC(13, 6),
    VLC(12, 6),
    VLC(11, 6),
    VLC2(10, 5),/* 0001 0 */
    VLC2(9, 5),
};

static const zero_count_t total_zero_table2_1[] = 
{
    VLC2(-1, -1),
    VLC(8, 4), /* 0010 */
    VLC(7, 4), /* 0011 */
    VLC(6, 4),
    VLC(5, 4),
    VLC2(4, 3),/* 011 */
    VLC2(3, 3),/* 100 */
    VLC2(2, 3), /*101 */
    VLC2(1, 3), /*110 */
    VLC2(0, 3), /*111 */
};

static const zero_count_t total_zero_table3_0[] = 
{
    VLC(13, 6), /* 0000 00 */
    VLC(11, 6),
    VLC2(12, 5),/* 0000 1 */
    VLC2(10, 5),/* 0001 0 */
    VLC2(9, 5), /* 0001 1 */
};

static const zero_count_t total_zero_table3_1[] = 
{
    VLC2(-1, -1),
    VLC(8, 4), /* 0010 */
    VLC(5, 4), /* 0011 */
    VLC(4, 4),
    VLC(0, 4),
    VLC2(7, 3),/* 011 */
    VLC2(6, 3),/* 100 */
    VLC2(3, 3), /*101 */
    VLC2(2, 3), /*110 */
    VLC2(1, 3), /*111 */
};

static const zero_count_t total_zero_table6_0[] = 
{
    VLC(10, 6), /* 0000 00 */
    VLC(0, 6),
    VLC2(1, 5),/* 0000 1 */
    VLC4(8, 4),/* 0000 1 */
};

static const zero_count_t total_zero_table6_1[] = 
{
    VLC(-1, -1),
    VLC(9, 3), /* 001 */
    VLC(7, 3), /* 010 */
    VLC(6, 3),
    VLC(5, 3),
    VLC(4, 3),
    VLC(3, 3),
    VLC(2, 3)
};

static const zero_count_t total_zero_table7_0[] = 
{
    VLC(9, 6), /* 0000 00 */
    VLC(0, 6),
    VLC2(1, 5),/* 0000 1 */
    VLC4(7, 4),/* 0001 */
};

static const zero_count_t total_zero_table7_1[] = 
{
    VLC(-1, -1),
    VLC(8, 3), /* 001 */
    VLC(6, 3), /* 010 */
    VLC(4, 3),
    VLC(3, 3),
    VLC(2, 3),
    VLC2(5, 2)
};

static const zero_count_t total_zero_table8_0[] = 
{
    VLC(8, 6), /* 0000 00 */
    VLC(0, 6),
    VLC2(2, 5),/* 0000 1 */
    VLC4(1, 4),/* 0001 */
};

static const zero_count_t total_zero_table8_1[] = 
{
    VLC(-1, -1),
    VLC(7, 3), /* 001 */
    VLC(6, 3), /* 010 */
    VLC(3, 3),
    VLC2(5, 2),
    VLC2(4, 2)
};

static const zero_count_t total_zero_table9_0[] = 
{
    VLC(1, 6), /* 0000 00 */
    VLC(0, 6),
    VLC2(7, 5),/* 0000 1 */
    VLC4(2, 4),/* 0001 */
};

static const zero_count_t total_zero_table9_1[] = 
{
    VLC(-1, -1),
    VLC(5, 3), /* 001 */
    VLC2(6, 2), /* 01 */
    VLC2(4, 2),
    VLC2(3, 2),
};

static const zero_count_t total_zero_table4_0[] = 
{
    VLC(12, 5), /* 0000 0 */
    VLC(11, 5),
    VLC(10, 5), /* 0000 1 */
    VLC(0, 5),  /* 0001 1 */
    VLC2(9, 4), /* 0010 */
    VLC2(7, 4),
    VLC2(3, 4),
    VLC2(2, 4), /* 0101 */
    VLC4(8, 3), /* 011 */
};

static const zero_count_t total_zero_table4_1[] = 
{
    VLC(6, 3),   /* 100 */
    VLC(5, 3),   /* 101 */
    VLC(4, 3),   /* 110 */
    VLC(1, 3)    /* 111 */
};

static const zero_count_t total_zero_table5_0[] = 
{
    VLC(11, 5),  /* 0000 0 */
    VLC(9, 5),
    VLC2(10, 4), /* 0000 1 */
    VLC2(8, 4),  /* 0010 */
    VLC2(2, 4),
    VLC2(1, 4),
    VLC2(0, 4),
    VLC4(7, 3)
};

static const zero_count_t total_zero_table5_1[] = 
{
    VLC(6, 3), /* 100 */
    VLC(5, 3),
    VLC(4, 3),
    VLC(3, 3)
};

static const zero_count_t total_zero_table10_0[] = 
{
    VLC(1, 5), /* 0000 0 */
    VLC(0, 5),
    VLC2(6, 4), /* 0000 1 */
};

static const zero_count_t total_zero_table10_1[] = 
{
    VLC(-1, -1),
    VLC(2, 3), /* 001 */
    VLC2(5, 2), /* 01 */
    VLC2(4, 2),
    VLC2(3, 2),
};

static const zero_count_t total_zero_table11_0[] = 
{
    VLC(0, 4), /* 0000 */
    VLC(1, 4),
    VLC2(2, 3), /* 010 */
    VLC2(3, 3),
    VLC2(5, 3),
    VLC8(4, 1)
};

static const zero_count_t total_zero_table12_0[] = 
{
    VLC(0, 4), /* 0000 */
    VLC(1, 4),
    VLC2(4, 3), /* 010 */
    VLC4(2, 2),
    VLC8(3, 1)
};

static const zero_count_t total_zero_table13_0[] = 
{
    VLC(0, 3), /* 000 */
    VLC(1, 3),
    VLC2(3, 2), /* 01 */
    VLC4(2, 1),
};

static const zero_count_t total_zero_table14_0[] = 
{
    VLC(0, 2), 
    VLC(1, 2),
    VLC2(2, 1),
};

static const zero_count_t total_zero_table_chroma[3][8] = 
{
    {
        VLC(3, 3), 
        VLC(2, 3),
        VLC2(1, 2),
        VLC4(0, 1)
    },
    {
        VLC2(2, 2),
        VLC2(1, 2),
        VLC4(0, 1)
    },
    {
        VLC4(1, 1),
        VLC4(0, 1)
    }
};

static const zero_count_t run_before_table_0[7][8] = 
{
    {
        VLC4(1, 1),
        VLC4(0, 1)
    },
    {
        VLC2(2, 2),
        VLC2(1, 2),
        VLC4(0, 1)
    },
    {
        VLC2(3, 2),
        VLC2(2, 2),
        VLC2(1, 2),
        VLC2(0, 2)
    },
    {
        VLC(4, 3),
        VLC(3, 3),
        VLC2(2, 2),
        VLC2(1, 2),
        VLC2(0, 2)
    },
    {
        VLC(5, 3),
        VLC(4, 3),
        VLC(3, 3),
        VLC(2, 3),
        VLC2(1, 2),
        VLC2(0, 2),
    },
    {
        VLC(1, 3),
        VLC(2, 3),
        VLC(4, 3),
        VLC(3, 3),
        VLC(6, 3),
        VLC(5, 3),
        VLC2(0, 2)
    },
    {
        VLC(-1, -1),
        VLC(6, 3),
        VLC(5, 3),
        VLC(4, 3),
        VLC(3, 3),
        VLC(2, 3),
        VLC(1, 3),
        VLC(0, 3)
    }
};

static const uint8_t run_before_table_1[] =
{
    -1,
    10,
    9, 9,
    8, 8, 8, 8,
    7, 7, 7, 7, 7, 7, 7, 7
};

static const uint8_t run_before_table_2[] =
{
    -1,
    14,
    13, 13,
    12, 12, 12, 12,
    11, 11, 11, 11, 11, 11, 11, 11
};
/* -- cavlc tables -- */

static void __inline
T264_mb_read_cavlc_i4x4_mode(T264_t* t)
{
    int32_t i, j;
    int32_t x, y;
    int8_t* p = t->mb.i4x4_pred_mode_ref;

    for(i = 0 ; i < 16 ; i ++)
    {
        int8_t pred;
        j = luma_index[i];

        pred = T264_mb_predict_intra4x4_mode(t, i);
        /* prev_intra4x4_pred_mode_flag */
        if (eg_read_direct1(t->bs))
        {
            t->mb.mode_i4x4[i] = pred;
        }
        else
        {
            int32_t mode = eg_read_direct(t->bs, 3);
            if (mode < pred)
            {
                t->mb.mode_i4x4[i] = mode;
            }
            else
            {
                t->mb.mode_i4x4[i] = mode + 1;
            }
        }

        x = j % 4;
        y = j / 4;
        p[IPM_LUMA + y * 8 + x] = t->mb.mode_i4x4[i];
    }
}

/* nC == -1 */
void
T264dec_mb_read_coff_token_t4(T264_t* t, uint8_t* trailing_ones, uint8_t* total_coff)
{
    int32_t code;

    code = eg_show(t->bs, 8);
    if (code >= 16)
    {
        if (code >= 128)
        {
            /* 1 */
            *trailing_ones = 1;
            *total_coff = 1;
            eg_read_skip(t->bs, 1);
        }
        else if (code >= 64)
        {
            /* 01 */
            *trailing_ones = 0;
            *total_coff = 0;
            eg_read_skip(t->bs, 2);
        }
        else if (code >= 32)
        {
            /* 001 */
            *trailing_ones = 2;
            *total_coff = 2;
            eg_read_skip(t->bs, 3);
        }
        else
        {
            code = (code >> 2) - 4;

            *trailing_ones = coeff4_0[code].trailing_ones;
            *total_coff = coeff4_0[code].total_coeff;
            eg_read_skip(t->bs, 6);
        }
    }
    else
    {
        *trailing_ones = coeff4_1[code].trailing_ones;
        *total_coff = coeff4_1[code].total_coeff;
        eg_read_skip(t->bs, coeff4_1[code].len);
    }
}

/* nC >= 8 */
void
T264dec_mb_read_coff_token_t3(T264_t* t, uint8_t* trailing_ones, uint8_t* total_coff)
{
    int32_t code;

    code = eg_read_direct(t->bs, 6);

    *trailing_ones = coeff3_0[code].trailing_ones;
    *total_coff = coeff3_0[code].total_coeff;
}

/* 8 > nC >= 4 */
void
T264dec_mb_read_coff_token_t2(T264_t* t, uint8_t* trailing_ones, uint8_t* total_coff)
{
    int32_t code;
    const vlc_coeff_token_t* table;

    code = eg_show(t->bs, 10);
    if (code >= 512)
    {
        table = coeff2_0;
        code = (code >> 6) - 8;
    }
    else if (code >= 256)
    {
        table = coeff2_1;
        code = (code >> 5) - 8;
    }
    else if (code >= 128)
    {
        table = coeff2_2;
        code = (code >> 4) - 8;
    }
    else if (code >= 64)
    {
        table = coeff2_3;
        code = (code >> 3) - 8;
    }
    else if (code >= 32)
    {
        table = coeff2_4;
        code = (code >> 2) - 8;
    }
    else if (code >= 16)
    {
        table = coeff2_5;
        code = (code >> 1) - 8;
    }
    else
    {
        table = coeff2_6;
    }

    *trailing_ones = table[code].trailing_ones;
    *total_coff = table[code].total_coeff;
    eg_read_skip(t->bs, table[code].len);
}

/* 4 > nC >= 2 */
void
T264dec_mb_read_coff_token_t1(T264_t* t, uint8_t* trailing_ones, uint8_t* total_coff)
{
    int32_t code;
    const vlc_coeff_token_t* table;

    code = eg_show(t->bs, 14);
    if (code >= 4096)
    {
        table = coeff1_0;
        code = (code >> 10) - 4;
    }
    else if (code >= 1024)
    {