Function cvSeqInsert

deps/opencv/modules/core/src/datastructs.cpp:1243–1357

Insert new element in middle of sequence: */

/* Insert new element in middle of sequence: */
CV_IMPL schar*
cvSeqInsert( CvSeq *seq, int before_index, const void *element )
{
    int elem_size;
    int block_size;
    CvSeqBlock *block;
    int delta_index;
    int total;
    schar* ret_ptr = 0;

    if( !seq )
        CV_Error( CV_StsNullPtr, "" );

    total = seq->total;
    before_index += before_index < 0 ? total : 0;
    before_index -= before_index > total ? total : 0;

    if( (unsigned)before_index > (unsigned)total )
        CV_Error( CV_StsOutOfRange, "" );

    if( before_index == total )
    {
        ret_ptr = cvSeqPush( seq, element );
    }
    else if( before_index == 0 )
    {
        ret_ptr = cvSeqPushFront( seq, element );
    }
    else
    {
        elem_size = seq->elem_size;

        if( before_index >= total >> 1 )
        {
            schar *ptr = seq->ptr + elem_size;

            if( ptr > seq->block_max )
            {
                icvGrowSeq( seq, 0 );

                ptr = seq->ptr + elem_size;
                assert( ptr <= seq->block_max );
            }

            delta_index = seq->first->start_index;
            block = seq->first->prev;
            block->count++;
            block_size = (int)(ptr - block->data);

            while( before_index < block->start_index - delta_index )
            {
                CvSeqBlock *prev_block = block->prev;

                memmove( block->data + elem_size, block->data, block_size - elem_size );
                block_size = prev_block->count * elem_size;
                memcpy( block->data, prev_block->data + block_size - elem_size, elem_size );
                block = prev_block;