NAME   

        BltClear - Clear a block of memory words to zero.

   SYNOPSIS
        BltClear( memBlock, bytecount, flags )
                    a1         d0       d1

        void BltClear( void *, ULONG, ULONG );

   FUNCTION
        For memory that is local and blitter accessible, the most
        efficient way to clear a range of memory locations is
       to use the system's most efficient data mover, the blitter.
       This command accepts the starting location and count and clears
       that block to zeros.

   INPUTS
        memBloc - pointer to local memory to be cleared
                  memBlock is assumed to be even.
        flags   - set bit 0 to force function to wait until
                  the blit is done.
                  set bit 1 to use row/bytesperrow.

        bytecount - if (flags & 2) == 0 then
                                even number of bytes to clear.
                        else
                                low 16 bits is taken as number of bytes
                                per row and upper 16 bits taken as
                                number of rows.

        This function is somewhat hardware dependent. In the rows/bytesperrow
        mode (with the pre-ECS blitter) rows must be <- 1024. In bytecount mode
        multiple runs of the blitter may be used to clear all the memory.

        Set bit 2 to use the upper 16 bits of the Flags as the data to fill
        memory with instead of 0 (V36).

   RESULT
        The block of memory is initialized.

   BUGS

   SEE ALSO