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zig defaults the wasm stack to 16MB, and that lands in the module's *initial*
memory, so every instance allocated 16.25MB before executing an instruction.
With several Game Boys on one page that was the dominant cost: 123MB for six.
The machine is a static and nothing here recurses deeply, so 256KB is plenty.
Per instance: 20.5MB -> 4.8MB of linear memory (six: 123MB -> 29MB). Note the
spelling - zig cc rejects -Wl,--stack-size and -zstack-size, and wants
-Wl,-z,stack-size=N.
With memory no longer the constraint, the page cap goes 6 -> 8 on measurement
rather than guesswork. Emulation-only, one thread: 12.5x realtime at 1, 3.1x
at 4, 1.5x at 8, and exactly 1.0x at 12 - i.e. ~12 is where a thread runs out
of road with nothing left for rendering. 8 holds a verified 60fps each in a
real browser with all eight leased.
Golden frames are still pixel-exact on cgb-acid2, dmg-acid2, cpu_instrs@600
and pky@400 with its .sav, and two Game Boys still lease and ping 4/4.
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/net.html plugs Game Boys into a switch that leases them addresses and routes
between them: add one, add another, and they ping each other. Unplug either
and its address goes back to the pool for the next one.
web/gbhub.js is tools/gbhub (gbos) ported to the browser - SLIP framing, DHCP
OFFER/ACK, unicast routing, broadcast flooding and ICMP echo for the gateway.
It deliberately has no uplink: NAT needs a TUN device and a tab has no raw
sockets, so packets addressed off-net are dropped and logged as "no route"
rather than pretending.
web/gbcore.js wraps one wasm instantiation as a GameBoy object. Several Game
Boys are several instantiations of the same compiled Module - the core keeps
its machine in a static, so each gets its own linear memory and is isolated
for free. Measured 12.3x realtime per instance, so the page caps at 6.
Each card gets a text input, because unframed link bytes are console I/O: it
lands on the shell's stdin like tools/gbtype, so you can run `ping 10.0.0.3`
without the on-screen keyboard.
Verified headless (node, two Game Boys through the hub: 2/2 leases, ping
4/4 received) and in headless Chrome against the live site: 4 Game Boys at
60fps each, leases .2-.5, typing into a card's console pings another, unplug
frees the address and a replug reclaims it, no exceptions.
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