//  [c]
int my_csr_reader( const char*           i_csr_file_in,
                    unsigned int**        o_row_idx,
                    unsigned int**        o_column_idx,
                    REALTYPE**            o_values,
                    unsigned int*         o_row_count,
                    unsigned int*         o_column_count,
                    unsigned int*         o_element_count ) {
  FILE *l_csr_file_handle;
  const unsigned int l_line_length = 512;
  char l_line[512/*l_line_length*/+1];
  unsigned int l_header_read = 0;
  unsigned int* l_row_idx_id = NULL;
  unsigned int l_i = 0;

  l_csr_file_handle = fopen( i_csr_file_in, "r" );
  if ( l_csr_file_handle == NULL ) {
    fprintf( stderr, "cannot open CSR file!\n" );
    return -1;
  }

  while (fgets(l_line, l_line_length, l_csr_file_handle) != NULL) {
    if ( strlen(l_line) == l_line_length ) {
      fprintf( stderr, "could not read file length!\n" );
      return -1;
    }
    /* check if we are still reading comments header */
    if ( l_line[0] == '%' ) {
      continue;
    } else {
      /* if we are the first line after comment header, we allocate our data structures */
      if ( l_header_read == 0 ) {
        if ( sscanf(l_line, "%u %u %u", o_row_count, o_column_count, o_element_count) == 3 ) {
          /* allocate CSC datastructure matching mtx file */
          *o_column_idx = (unsigned int*) malloc(sizeof(unsigned int) * (*o_element_count));
          *o_row_idx = (unsigned int*) malloc(sizeof(unsigned int) * (*o_row_count + 1));
          *o_values = (REALTYPE*) malloc(sizeof(double) * (*o_element_count));
          l_row_idx_id = (unsigned int*) malloc(sizeof(unsigned int) * (*o_row_count));

          /* check if mallocs were successful */
          if ( ( *o_row_idx == NULL )      ||
               ( *o_column_idx == NULL )   ||
               ( *o_values == NULL )       ||
               ( l_row_idx_id == NULL ) ) {
            fprintf( stderr, "could not allocate sp data!\n" );
            return -1;
          }

          /* set everything to zero for init */
          memset(*o_row_idx, 0, sizeof(unsigned int)*(*o_row_count + 1));
          memset(*o_column_idx, 0, sizeof(unsigned int)*(*o_element_count));
          memset(*o_values, 0, sizeof(double)*(*o_element_count));
          memset(l_row_idx_id, 0, sizeof(unsigned int)*(*o_row_count));

          /* init column idx */
          for ( l_i = 0; l_i < (*o_row_count + 1); l_i++)
            (*o_row_idx)[l_i] = (*o_element_count);

          /* init */
          (*o_row_idx)[0] = 0;
          l_i = 0;
          l_header_read = 1;
        } else {
          fprintf( stderr, "could not csr description!\n" );
          return -1;
        }
      /* now we read the actual content */
      } else {
        unsigned int l_row, l_column;
        REALTYPE l_value;
        /* read a line of content */
        if ( sscanf(l_line, "%u %u %lf", &l_row, &l_column, &l_value) != 3 ) {
          fprintf( stderr, "could not read element!\n" );
          return -1;
        }
        /* adjust numbers to zero termination */
        l_row--;
        l_column--;
        /* add these values to row and value structure */
        (*o_column_idx)[l_i] = l_column;
        (*o_values)[l_i] = l_value;
        l_i++;
        /* handle columns, set id to own for this column, yeah we need to handle empty columns */
        l_row_idx_id[l_row] = 1;
        (*o_row_idx)[l_row+1] = l_i;
      }
    }
  }

  /* close mtx file */
  fclose( l_csr_file_handle );

  /* check if we read a file which was consistent */
  if ( l_i != (*o_element_count) ) {
    fprintf( stderr, "we were not able to read all elements!\n" );
    return -1;
  }

  /* let's handle empty rows */
  for ( l_i = 0; l_i < (*o_row_count); l_i++) {
    if ( l_row_idx_id[l_i] == 0 ) {
      (*o_row_idx)[l_i+1] = (*o_row_idx)[l_i];
    }
  }

  /* free helper data structure */
  if ( l_row_idx_id != NULL ) {
    free( l_row_idx_id );
  }
  return 0;
}