gbos.git/c/ping.c, branch master

refactor: c/ -> usr/, compiled program blobs out of the source tree

2026-07-17T22:38:38Z

Userland sources live in usr/ (fits the Unix theme better than 'c'). SDCC output .bin blobs land in build/usr/ with the other build artifacts instead of littering the source dir; programs.asm INCBINs them from there. Byte-identical ROM.

net: unbreak ping against hosts that intermittently drop ICMP

2026-07-17T17:45:13Z

Pinging sl0p.foo through gbhub looked hung: DNS resolved, then nothing. Packet-tracing showed the echo request leaving the hub's TUN and eth0 correctly NATed every time - but 80.78.19.56 blackholes ICMP for all ids in windows of tens of seconds (provider rate limiting). One lost reply wedged ping for minutes because net_recv's pump-counted timeout is effectively unbounded at native emulation speed. Two fixes: - NET_RECVNB (op 8): non-blocking recv - one RX pump, $FE if nothing buffered, same delivery/EOF semantics as NET_RECV otherwise. ping now waits <=~2s per seq (net_recv_nb + msleep loop), prints 'seq=N timeout' and moves on, like real ping. - ICMP echo id was hardcoded $1234 for every GB, every boot, so all sessions produced byte-identical flows - hostile to NAT conntrack (keyed on icmp id). wNetEchoId is now our host octet + rDIV timing noise sampled at DHCP lease, distinct per GB and per boot. Verified: 8 back-to-back native-speed gbhub runs, zero hangs; a run that hit a blackhole window printed seq=1 timeout then recovered to 3/4 received. GB<->GB ping and DNS/DHCP unaffected.

net: ping resolves hostnames (ping sl0p.foo, not just ping 1.2.3.4)

2026-07-17T13:23:03Z

ping used parse_ip only, so a hostname gave "bad address". It now uses resolve.h (like wget/nslookup): dotted-quad is used as-is, a name is looked up via DNS first. Copies the arg to a safe buffer before resolving (the 0xA000 arg/_DATA overlap dance). Verified through DHCP + NAT: /# ping sl0p.foo PING 80.78.19.56 reply from 80.78.19.56 seq=1 ... -- 4/4 received

kernel: sys_sleep - a cooperative delay off the DIV timer (+ ping pacing)

2026-07-17T11:43:10Z

There was no time source at all (IRQ vectors just reti; scheduler is purely cooperative). The DIV register (FF04) free-runs at 16384 Hz regardless of interrupts, so sys_sleep accumulates DIV deltas across SchedYields (other procs keep running) until the requested number of 1/64-second units elapse. - SYS_SLEEP(34): B = 1/64s units; libc gsleep(units) / msleep(ms) wrappers. - ping now msleep(800) between echoes, so it paces like real ping instead of blasting all four at once. Verified real-time (capped emulator): replies land ~0.85s apart. In --uncapped runs the delay is GB-time (fast wall-clock), as expected.

net: proper socket API in the kernel (SYS_NET) - no more SLIP in userland

2026-07-17T10:39:01Z

The network stack moves into the kernel. src/socket.asm owns SLIP framing, IPv4, RFC1071 checksums, and ICMP; programs now speak a socket API through one syscall (SYS_NET, DE=&netreq dispatched by op): net_socket/connect/send/recv/ close/poll (c/sock.h). No program touches SLIP, IP headers, or checksums. - Socket table (4 sockets) + tx/rx buffers in WRAM0; our IP = 10.0.0.2. - net_pump: drains the link, reassembles SLIP frames, demuxes IPv4. Inbound ICMP echo requests are auto-answered in-kernel, so the GB replies to pings whenever any process pumps RX. - ICMP sockets: send() emits an echo request to the connected peer; recv() returns the matching reply (with a spin/yield timeout). ping.c is now a ~15-line socket client; netd.c is just `for(;;){net_poll(); yield();}`. Verified over tunbridge: /# ping 1.1.1.1 -> replies from the real internet (kernel builds it all) host# ping 10.0.0.2 -> 4/4, 0% loss (kernel auto-answers) Gotchas recorded: gbos.inc isn't a make dep (touch asm after editing); this crt0 doesn't copy initializers (fill arrays at runtime); and the arg string at 0xA000 overlaps _DATA, so parse targets must sit past it (big buffer first). UDP and TCP sockets build on this same core next.

net: ping - GB-originated ICMP echo (a Game Boy pings the real internet)

2026-07-17T10:15:09Z

New `ping [A.B.C.D]` program (PROG_PING=27, bank 29): builds and sends ICMP echo requests from 10.0.0.2, then reads replies off the link port. It keeps reading SLIP frames until it finds *our* echo reply, skipping the IGMP/mDNS/ SSDP multicast noise that shares 10.0.0.0/24. Reply wait uses a generous srecv_nb spin budget since the emulator runs uncapped (no timer syscall yet). Verified over the tunbridge (with NAT): /# ping 10.0.0.1 -> 4/4 received, ttl=64 (the SLIP peer/host) /# ping 1.1.1.1 -> 4/4 received, ttl=56 (Cloudflare, real net!) ttl=56 is a real internet round trip (64 minus the hops). Combined with the host being able to ping the GB, the Game Boy is now a full two-way ICMP host.