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|
use io;
use fmt;
use endian;
use drawing;
export type error = !str;
export type packet_reader = struct {
buf: []u8,
good: []u8,
};
export fn new() packet_reader = {
let pr = packet_reader {
buf = alloc([0...],512*512*4*2), // ehhh
...
};
pr.good = pr.buf[0..0];
return pr;
};
export type packet_type = enum u8 {
DRAW_OP,
SEND_CHUNK,
};
export type packet_drawop = drawing::op;
export type packet_sendchunk = []u32;
export type packet = (packet_drawop | packet_sendchunk);
// call when input is ready. could block otherwise
export fn read(pr: *packet_reader, sock: io::handle) (void | io::error | io::EOF) = {
const remaining_amt = len(pr.good);
const read_pos = if (remaining_amt > 0) {
// still some unconsumed content in the buffer
// move unconsumed stuff to start of buffer
fmt::printfln("moving {} remaining bytes",remaining_amt)!;
pr.buf[0..remaining_amt] = pr.good;
yield remaining_amt;
} else 0z;
const nread = match(io::read(sock, pr.buf[read_pos..])?) {
case io::EOF => return io::EOF;
case let n: size => yield n;
};
fmt::printfln("read {} bytes",nread)!;
const total_amt = read_pos + nread;
pr.good = pr.buf[0..total_amt];
fmt::printfln("now {} bytes in buffer",total_amt)!;
};
// packet format:
// u32 size
// u32 type
// [size-8]u8 data...
// size includes size of header (size and type fields)
export fn next(pr: *packet_reader) (packet | done | error) = {
// either parse a full packet out of the front of good,
// move good along that many bytes,
// and return the packet,
// or, ascertain there is no full packet, and return done
if (len(pr.good) < size(u32)) return done;
const packet_len = endian::legetu32(pr.good[0..4]);
if (packet_len < 8) return "packet size field too small": error;
if (len(pr.good) < packet_len) return done;
const packet_bytes = pr.good[..packet_len];
pr.good = pr.good[packet_len..];
const ty = endian::legetu32(packet_bytes[4..8]): packet_type;
switch (ty) {
case packet_type::DRAW_OP =>
const op = drawing::deser_op(packet_bytes[8..]);
return op: packet_drawop;
case packet_type::SEND_CHUNK =>
// in an ideal world we would need no copies
const totally_necessary_copy = alloc(packet_bytes[8..]...);
return totally_necessary_copy: packet_sendchunk;
};
};
export fn send_raw(sock: io::file, ty: packet_type, data: []u8) (void | io::error) = {
// ehh
const header: [8]u8 = [0...];
endian::leputu32(header[0..4], 8u32 + len(data):u32);
endian::leputu32(header[4..8], ty);
io::writeall(sock, header)?;
io::writeall(sock, data)?;
};
export fn send(sock: io::file, packet: packet) (void | io::error) = {
match (packet) {
case let op: packet_drawop =>
const ser_op = drawing::ser_op(op);
defer free(ser_op);
send_raw(sock, packet_type::DRAW_OP, ser_op)?;
case let chunkdata: packet_sendchunk =>
abort("not implemented sendchunk yet");
};
};
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