include "draw.m";   # for Draw->Pointer
include "devpointer.m";
ptr:= load Devpointer Devpointer->PATH;

init:      fn(file: string, posn: chan of ref Draw->Pointer): int;
bytes2ptr: fn(buf: array of byte)    : ref Draw->Pointer;
ptr2bytes: fn(ptr: ref Draw->Pointer): array of byte;

Init spawns a process to read continually the pointer device specified by file and send a Pointer adts over the channel specified by posn. If file is nil, the default device is /dev/pointer.

Bytes2ptr converts the array of bytes buf to a Pointer and returns a reference to it. Buf should consist of exactly Devpointer->Size bytes and be in the format returned by /dev/pointer.

Ptr2bytes provides the inverse transformation of bytes2ptr: it packs the data into an array of bytes of appropriate format, which it returns.