ANSCORE/MediaClient/rtp/bs.h

#ifdef BS_H
#warning FIXME Multiple inclusion of bs.h
#else
#define BS_H

typedef struct bs_s
{
    uint8 * p_start;
    uint8 * p;
    uint8 * p_end;

    int		i_left;    /* i_count number of available bits */
} bs_t;

static inline void bs_init(bs_t *s, void *p_data, int i_data)
{
    s->p_start = (uint8 *)p_data;
    s->p       = (uint8 *)p_data;
    s->p_end   = s->p + i_data;
    s->i_left  = 8;
}

static inline int bs_pos(bs_t *s)
{
    return (int)(8 * (s->p - s->p_start) + 8 - s->i_left);
}

static inline int bs_left(bs_t *s)
{
    return (int)(8 * (s->p_end - s->p) + 8 - s->i_left);
}

static inline int bs_eof(bs_t *s)
{
    return (s->p >= s->p_end ? 1: 0);
}

static inline uint32 bs_read(bs_t *s, int i_count)
{
     static uint32 i_mask[33] = { 0x00,
                                  0x01,      0x03,      0x07,      0x0f,
                                  0x1f,      0x3f,      0x7f,      0xff,
                                  0x1ff,     0x3ff,     0x7ff,     0xfff,
                                  0x1fff,    0x3fff,    0x7fff,    0xffff,
                                  0x1ffff,   0x3ffff,   0x7ffff,   0xfffff,
                                  0x1fffff,  0x3fffff,  0x7fffff,  0xffffff,
                                  0x1ffffff, 0x3ffffff, 0x7ffffff, 0xfffffff,
                                  0x1fffffff,0x3fffffff,0x7fffffff,0xffffffff};
    int	i_shr;
    uint32 i_result = 0;

    while (i_count > 0)
    {
        if (s->p >= s->p_end)
        {
            break;
        }

        if ((i_shr = s->i_left - i_count) >= 0)
        {
            /* more in the buffer than requested */
            i_result |= (*s->p >> i_shr)&i_mask[i_count];
            s->i_left -= i_count;
            if (s->i_left == 0)
            {
                s->p++;
                s->i_left = 8;
            }
            
            return i_result;
        }
        else
        {
            /* less in the buffer than requested */
           i_result |= (*s->p&i_mask[s->i_left]) << -i_shr;
           i_count  -= s->i_left;
           s->p++;
           s->i_left = 8;
        }
    }

    return i_result;
}

static inline uint32 bs_read1(bs_t *s)
{
    if (s->p < s->p_end)
    {
        uint32 i_result;

        s->i_left--;
        
        i_result = (*s->p >> s->i_left)&0x01;
        if (s->i_left == 0)
        {
            s->p++;
            s->i_left = 8;
        }
        
        return i_result;
    }

    return 0;
}
static inline uint32 bs_show(bs_t *s, int i_count)
{
    if (s->p < s->p_end && i_count > 0)
    {
        uint32 i_cache = ((s->p[0] << 24)+(s->p[1] << 16)+(s->p[2] << 8)+s->p[3]) << (8-s->i_left);
        return (i_cache >> (32 - i_count));
    }
    
    return 0;
}

/* TODO optimize */
static inline void bs_skip(bs_t *s, int i_count)
{
    s->i_left -= i_count;

    while (s->i_left <= 0)
    {
        s->p++;
        s->i_left += 8;
    }
}

static inline int bs_read_ue(bs_t *s)
{
    int i = 0;

    while (bs_read1(s) == 0 && s->p < s->p_end && i < 32)
    {
        i++;
    }
    
    return ((1 << i) - 1 + bs_read(s, i));
}

static inline int bs_read_se(bs_t *s)
{
    int val = bs_read_ue(s);

    return val&0x01 ? (val+1)/2 : -(val/2);
}

static inline int bs_read_te(bs_t *s, int x)
{
    if (x == 1)
    {
        return 1 - bs_read1(s);
    }
    else if (x > 1)
    {
        return bs_read_ue(s);
    }
    
    return 0;
}

/* TODO optimize (write x bits at once) */
static inline void bs_write(bs_t *s, int i_count, uint32 i_bits)
{
    while (i_count > 0)
    {
        if (s->p >= s->p_end)
        {
            break;
        }

        i_count--;

        if ((i_bits >> i_count) & 0x01)
        {
            *s->p |= 1 << (s->i_left - 1);
        }
        else
        {
            *s->p &= ~(1 << (s->i_left - 1));
        }
        
        s->i_left--;
        
        if (s->i_left == 0)
        {
            s->p++;
            s->i_left = 8;
        }
    }
}

static inline void bs_write1(bs_t *s, uint32 i_bits)
{
    if (s->p < s->p_end)
    {
        s->i_left--;

        if (i_bits & 0x01)
        {
            *s->p |= 1 << s->i_left;
        }
        else
        {
            *s->p &= ~(1 << s->i_left);
        }
        
        if (s->i_left == 0)
        {
            s->p++;
            s->i_left = 8;
        }
    }
}

static inline void bs_align(bs_t *s)
{
    if (s->i_left != 8)
    {
        s->i_left = 8;
        s->p++;
    }
}

static inline void bs_align_0(bs_t *s)
{
    if (s->i_left != 8)
    {
        bs_write(s, s->i_left, 0);
    }
}

static inline void bs_align_1(bs_t *s)
{
    if (s->i_left != 8)
    {
        bs_write(s, s->i_left, ~0);
    }
}

/* golomb functions */

static inline void bs_write_ue(bs_t *s, uint32 val)
{
    int i_size = 0;
    static const int i_size0_255[256] =
    {
        1,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
        6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
        7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
        7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
        8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
        8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
        8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
        8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8
    };

    if (val == 0)
    {
        bs_write(s, 1, 1);
    }
    else
    {
        uint32 tmp = ++val;

        if (tmp >= 0x00010000)
        {
            i_size += 16;
            tmp >>= 16;
        }
        
        if (tmp >= 0x100)
        {
            i_size += 8;
            tmp >>= 8;
        }
        
        i_size += i_size0_255[tmp];

        bs_write(s, 2 * i_size - 1, val);
    }
}

static inline void bs_write_se(bs_t *s, int val)
{
    bs_write_ue(s, val <= 0 ? -val * 2 : val * 2 - 1);
}

static inline void bs_write_te(bs_t *s, int x, int val)
{
    if (x == 1)
    {
        bs_write(s, 1, ~val);
    }
    else if (x > 1)
    {
        bs_write_ue(s, val);
    }
}

static inline void bs_rbsp_trailing(bs_t *s)
{
    bs_write(s, 1, 1);
    
    if (s->i_left != 8)
    {
        bs_write(s, s->i_left, 0x00);
    }
}

static inline int bs_size_ue(uint32 val)
{
    static const int i_size0_254[255] =
    {
        1, 3, 3, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 7, 7,
        9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
        11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
        11,11,11,11,11,11,11,11,11,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
        13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
        13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,
        13,13,13,13,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
        15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
        15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
        15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
        15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,
        15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15
    };

    if (val < 255)
    {
        return i_size0_254[val];
    }
    else
    {
        int i_size = 0;

        val++;

        if (val >= 0x10000)
        {
            i_size += 32;
            val = (val >> 16) - 1;
        }
        
        if (val >= 0x100)
        {
            i_size += 16;
            val = (val >> 8) - 1;
        }
        
        return i_size0_254[val] + i_size;
    }
}

static inline int bs_size_se(int val)
{
    return bs_size_ue(val <= 0 ? -val * 2 : val * 2 - 1);
}

static inline int bs_size_te(int x, int val)
{
    if (x == 1)
    {
        return 1;
    }
    else if (x > 1)
    {
        return bs_size_ue(val);
    }
    
    return 0;
}

static inline uint8 * bs_data(bs_t *s)
{
	return s->p - (8 - s->i_left) / 8;
}

#endif