gbos.git/src/syscall.asm, branch master

term+libc: batched write rendering - one tile render per write(), 2.3x lines

2026-07-18T20:19:59Z

sys_write sets wBatch; render_cursor_tile - the single choke point all of term_putc's visible mutations pass through - then marks a dirty span (per LINE-SLOT, so spans survive scroll rotation for free) instead of rendering. term_write_end renders every dirty tile exactly once, then the cursor. Scrolls stay immediate (blank rebuild is cheap and artifact-free); file-bound writes flush for free. The enabler is in libc: puts() was a SYS_PUTC trap PER CHARACTER, so almost no console output ever went through sys_write. It now issues one SYS_WRITE for the whole string - one trap, one batch, and every line-printer (echo, irc, the shell) gets the batched path. Measured: 37-char write = 128k cycles (3.5k/char) vs ~8k/char down the per-char trap path. Full demo passes; GIF regenerated.

kernel: CGB double-speed mode - 2x everything (1.99x measured)

2026-07-18T20:06:35Z

KEY1 prepare + STOP at KernelInit (skipped on warm reboot if already fast). The PPU/LCD keep their normal rate; the timer and DIV double with the CPU, compensated at the two consumers: - TimerISR now fires at 128 Hz; a toggle byte keeps wTicks at 64 Hz (uptime semantics unchanged) - sys_sleep halves the DIV-delta accumulator's high byte (256 DIV ticks = 1/128 s in double speed) so gsleep/msleep stay real-time Measured: count 60 (scroll-heavy) 3.77s -> 1.89s wall; wTicks 64 Hz over 4s; ping's 800ms msleep pacing unchanged (2.77s for 4 echoes). sl0pboy already emulated KEY1/STOP + per-speed timer/PPU rates.

kernel: a real timer source (64 Hz tick IRQ) + uptime(1)

2026-07-18T08:10:17Z

The kernel had no clock: TimerISR was a reti stub, IEF_TIMER masked, and IME was never enabled - the vectors were decorative. sys_sleep just polls DIV deltas per-process; nothing counted globally. Now: TAC runs the hardware timer at 16384 Hz with TMA=0, so TIMA overflows at exactly 64 Hz; TimerISR increments a monotonic 32-bit wTicks (wraps after ~2.1 years). Scheduling stays cooperative - the ISR is transparent. Enabling IME in a kernel written for zero interrupts needs care wherever SP points into memory whose bank is being switched (an IRQ pushes onto SP): - read_block/write_block map the disk bank over the $A000 window that holds the caller's stack -> di/ei around the transfer (~2ms, well under the 15.6ms tick period, so no tick is ever lost) - hSwitchTo switches SVBK + cart-RAM banks under the outgoing stack -> di on entry, ei once the incoming stack is mapped - fork already runs on KSTACK_TOP2 (fixed WRAM) - safe as-is - term_putc's SVBK switch only remaps $Dxxx, stacks live in $Axxx/$Cxxx SYS_UPTIME (36) copies the counter (4B LE, di/ei so the read can't tear) to a user buffer; libc gticks(); usr/uptime.c formats 'up [Nd] H:MM:SS'. uptime avoids SDCC long div/shift entirely: sm83.lib modules link into their own areas that land in the $A000 RAM window (latent build.sh trap, documented there) - bytewise >>6 plus bounded subtraction loops instead.

net: SYS_POLLCON + larger console ring for link-injected input

2026-07-17T18:22:34Z

Programs that own their main loop (the IRC client) need to poll for typed input without blocking. pollin() only sees the on-screen keyboard; bytes injected over the link (gbhub 'type', for scripted/hub-driven sessions) land in the kernel console ring, previously only drained by the blocking KGetc path. Add SYS_POLLCON: a non-blocking con_pop for userland. Also enlarge that console ring 16 -> 64. One net_pump drains an entire serial burst into the ring at once, so a whole injected command line has to fit or bytes are dropped and lines merge (a 20-char command came out truncated and glued to the next). 64 covers a full line; mask stays a power of two.

net: pump the network from the console wait (answer pings at the prompt)

2026-07-17T13:12:11Z

A Game Boy sitting at the shell prompt now services the network instead of being deaf until you run netd: KGetc (the console input wait) pumps net_pump each poll, so inbound pings are auto-answered while idle. net_pump gained an in-frame model and routes any non-framed link bytes to a small console-input ring (con_push/con_pop), so a headless-injected command still reaches the shell while SLIP frames go to the stack. Removes the old SLIP-skip-in-KGetc hack. Verified: two Game Boys on the hub, GB0 idle at the prompt (no netd), GB1 `ping 10.0.0.2` -> 4/4 replies, routed GB1->hub->GB0->hub->GB1. (Separate, pre-existing: gbhub *spawn* mode and windowed gbjoin can drop an idle link socket - under investigation; daemon mode + headless is solid.)

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: keep network packets out of the console (fixes shell garbage on netboot)

2026-07-17T11:29:42Z

The link port is both the console-input fallback and the network. At the shell prompt the host's multicast (mDNS/LLMNR/IGMP) was fed to the serial and KGetc read those packet bytes as console input -> garbage in the shell, OSK unusable. Two-part fix: - KGetc now skips SLIP frames (0xC0-delimited) on the serial console path, so inbound packets never surface as console input. Plain injected bytes (the headless tunbridge command path) still pass through. New wConInSkip flag. - netboot/tunbridge only forward IP packets destined to 10.0.0.2 (drop the multicast noise at the bridge). Verified: GB sits at a clean "/#" prompt while all packets (noise included) are forwarded; being-pinged (3/3) and wget still work. On the emulator, the OSK is SELECT=space, START=enter, A=z, B=x, d-pad=WASD/arrows.

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: chat client - async receive + OSK send over the link port

2026-07-16T23:39:29Z

The application layer of the link-port demo, and it ties the whole system together: the LCD terminal displays, the on-screen keyboard types, and the link port carries a live chat. Kernel: sys_srecv_nb (non-blocking link receive; A=byte, CF=none) and sys_pollin (poll the OSK for a typed char without blocking) - syscalls 31/32. Both are what a poll loop needs to receive and type at once. Userland: c/chat.c runs a poll loop - it feeds non-blocking bytes through a SLIP receive state machine and prints whole incoming frames as messages, while pollin() drives the on-screen keyboard; SELECT shows the keys, type a line, START sends it as a frame. libc srecv_nb()/pollin(). Host: tools/gateway.py --mode chat is a simple bot peer (echoes each GB message and injects a few async ones); --keys can drive the OSK for tests. Verified: the gateway pushes 'welcome', ' hey gameboy!', ' nice link cable' unprompted and the GB displays all three (async receive); typing 'hi' on the OSK echoes it and emits the SLIP frame \xC0hi\xC0 (send). A Game Boy in the chat, keyboard on screen, over the link cable.

net: SLIP framing over the link port + a host gateway (echo round-trip)

2026-07-16T23:28:23Z

First step of link-port networking. The LCD terminal + OSK freed the serial port from console duty, so it can be the network link. Kernel (src/net.asm): raw link-port serial that bypasses the console/ terminal - sys_ssend (transmit, GB drives the clock) and sys_srecv (receive, GB slave, blocks by yielding). Syscalls 29/30. Userland: libc ssend()/srecv(); c/necho.c does SLIP (RFC 1055) framing over them - send a packet, receive the reply, print it. Host: tools/gateway.py wraps the emulator, owns its link serial, speaks SLIP, and (for now) echoes every frame back - the "link cable adapter". Console (ASCII) bytes on the same channel are printed for visibility. Verified: `necho` sends a SLIP frame, the gateway decodes+echoes it, and gbos prints the reply - a real framed round-trip over the Game Boy link port. Next: swap the echo for actual network ops (DNS/HTTP or IRC/chat).