/****************************************************************************
 * Func: trans_pgm                                                          *
 *                                                                          *
 * Desc: translates a block in an image                                     *
 *                                                                          *
 * Params: buffer - pointer to image in memory                              *
 *         out_buffer - pointer to output image in memory                   *
 *         rows - number of rows in image                                   *
 *         cols - number of columns in image                                *
 *         x_start - Upper left x coordinate of block to move               *
 *         y_start - Upper left y coordinate of block to move               *
 *         x_end - x coordinate of destination                              *
 *         y_end - y coordinate of destination                              *
 *         width - width of block to move                                   *
 *         height - height of block to move                                 *
 ****************************************************************************/

void trans_pgm(image_ptr buffer, image_ptr out_buffer, int rows, int cols, int x_start,
	       int y_start, int x_end, int y_end, int width, int height)
    {
    int x,y;                         /* column and row indices in image */
    unsigned long sourceadd, destadd;/* address in source and dest images */
    unsigned long index;             /* index into images */

    /* copy source image to destination */
    index = 0;
    for(y=0; y<rows; y++)
	for(x=0; x<cols; x++)
	    out_buffer[index] = buffer[index++];

    /* translate specific block */
    for(y=0; y<height; y++)
	for(x=0; x<width; x++)
	    {
	    sourceadd = ((unsigned long)y_start+y) * cols + x_start + x;
	    destadd = ((unsigned long)y_end+y) * cols + x_end +x;
	    out_buffer[destadd] = buffer[sourceadd];
	    }
    }