static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf,
                            int buf_size, int block_width, int block_height,
                            uint8_t *previous_frame, int *I_frame)
{
    PutBitContext pb;
    int h_blocks, v_blocks, h_part, v_part, i, j;
    int buf_pos, res;
    int pred_blocks = 0;
    init_put_bits(&pb, buf, buf_size * 8);
    put_bits(&pb,  4, block_width / 16 - 1);
    put_bits(&pb, 12, s->image_width);
    put_bits(&pb,  4, block_height / 16 - 1);
    put_bits(&pb, 12, s->image_height);
    flush_put_bits(&pb);
    buf_pos = 4;
    h_blocks = s->image_width  / block_width;
    h_part   = s->image_width  % block_width;
    v_blocks = s->image_height / block_height;
    v_part   = s->image_height % block_height;
    for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
        int y_pos = j * block_height;
        int cur_blk_height = (j < v_blocks) ? block_height : v_part;
        for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
            int x_pos = i * block_width;
            int cur_blk_width = (i < h_blocks) ? block_width : h_part;
            int ret = Z_OK;
            uint8_t *ptr = buf + buf_pos;
            res = copy_region_enc(p->data[0], s->tmpblock,
                                  s->image_height - (y_pos + cur_blk_height + 1),
                                  x_pos, cur_blk_height, cur_blk_width,
                                  p->linesize[0], previous_frame);
            if (res || *I_frame) {
                unsigned long zsize = 3 * block_width * block_height;
                ret = compress2(ptr + 2, &zsize, s->tmpblock,
                                3 * cur_blk_width * cur_blk_height, 9);
                if (ret != Z_OK)
                    av_log(s->avctx, AV_LOG_ERROR,
                           "error while compressing block %dx%d\n", i, j);
                bytestream_put_be16(&ptr, zsize);
                buf_pos += zsize + 2;
                av_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
            } else {
                pred_blocks++;
                bytestream_put_be16(&ptr, 0);
                buf_pos += 2;
            }
        }
    }
    if (pred_blocks)
        *I_frame = 0;
    else
        *I_frame = 1;
    return buf_pos;
}
['static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf,\n                            int buf_size, int block_width, int block_height,\n                            uint8_t *previous_frame, int *I_frame)\n{\n    PutBitContext pb;\n    int h_blocks, v_blocks, h_part, v_part, i, j;\n    int buf_pos, res;\n    int pred_blocks = 0;\n    init_put_bits(&pb, buf, buf_size * 8);\n    put_bits(&pb,  4, block_width / 16 - 1);\n    put_bits(&pb, 12, s->image_width);\n    put_bits(&pb,  4, block_height / 16 - 1);\n    put_bits(&pb, 12, s->image_height);\n    flush_put_bits(&pb);\n    buf_pos = 4;\n    h_blocks = s->image_width  / block_width;\n    h_part   = s->image_width  % block_width;\n    v_blocks = s->image_height / block_height;\n    v_part   = s->image_height % block_height;\n    for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {\n        int y_pos = j * block_height;\n        int cur_blk_height = (j < v_blocks) ? block_height : v_part;\n        for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {\n            int x_pos = i * block_width;\n            int cur_blk_width = (i < h_blocks) ? block_width : h_part;\n            int ret = Z_OK;\n            uint8_t *ptr = buf + buf_pos;\n            res = copy_region_enc(p->data[0], s->tmpblock,\n                                  s->image_height - (y_pos + cur_blk_height + 1),\n                                  x_pos, cur_blk_height, cur_blk_width,\n                                  p->linesize[0], previous_frame);\n            if (res || *I_frame) {\n                unsigned long zsize = 3 * block_width * block_height;\n                ret = compress2(ptr + 2, &zsize, s->tmpblock,\n                                3 * cur_blk_width * cur_blk_height, 9);\n                if (ret != Z_OK)\n                    av_log(s->avctx, AV_LOG_ERROR,\n                           "error while compressing block %dx%d\\n", i, j);\n                bytestream_put_be16(&ptr, zsize);\n                buf_pos += zsize + 2;\n                av_dlog(s->avctx, "buf_pos = %d\\n", buf_pos);\n            } else {\n                pred_blocks++;\n                bytestream_put_be16(&ptr, 0);\n                buf_pos += 2;\n            }\n        }\n    }\n    if (pred_blocks)\n        *I_frame = 0;\n    else\n        *I_frame = 1;\n    return buf_pos;\n}', 'static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)\n{\n    if(buffer_size < 0) {\n        buffer_size = 0;\n        buffer = NULL;\n    }\n    s->size_in_bits= 8*buffer_size;\n    s->buf = buffer;\n    s->buf_end = s->buf + buffer_size;\n    s->buf_ptr = s->buf;\n    s->bit_left=32;\n    s->bit_buf=0;\n}', 'static inline void put_bits(PutBitContext *s, int n, unsigned int value)\n{\n    unsigned int bit_buf;\n    int bit_left;\n    assert(n <= 31 && value < (1U << n));\n    bit_buf = s->bit_buf;\n    bit_left = s->bit_left;\n#ifdef BITSTREAM_WRITER_LE\n    bit_buf |= value << (32 - bit_left);\n    if (n >= bit_left) {\n        AV_WL32(s->buf_ptr, bit_buf);\n        s->buf_ptr+=4;\n        bit_buf = (bit_left==32)?0:value >> bit_left;\n        bit_left+=32;\n    }\n    bit_left-=n;\n#else\n    if (n < bit_left) {\n        bit_buf = (bit_buf<<n) | value;\n        bit_left-=n;\n    } else {\n        bit_buf<<=bit_left;\n        bit_buf |= value >> (n - bit_left);\n        AV_WB32(s->buf_ptr, bit_buf);\n        s->buf_ptr+=4;\n        bit_left+=32 - n;\n        bit_buf = value;\n    }\n#endif\n    s->bit_buf = bit_buf;\n    s->bit_left = bit_left;\n}']