Write characters directly to the virtual display
unsigned int SLsmg_write_raw (unsigned short *buf, unsigned int len)
SLsmg_write_raw function attempts to write
characters specified by
buf to the display at the current
position. It returns the number of characters successfully written,
which will be less than
len if an attempt is made to write
past the right margin.
The purpose of the pair of functions,
SLsmg_write_raw, is to permit one to copy the contents of one
region of the virtual display to another region.