From b5544e84232b80351e7c58501c1632080a354d12 Mon Sep 17 00:00:00 2001 From: user Date: Fri, 17 Jul 2026 01:28:23 +0200 Subject: net: SLIP framing over the link port + a host gateway (echo round-trip) 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). --- c/libc.s | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'c/libc.s') diff --git a/c/libc.s b/c/libc.s index ec59bb7..50d7860 100644 --- a/c/libc.s +++ b/c/libc.s @@ -1,6 +1,6 @@ .module libc .globl _writes, _putc, _puts, _nl, _strlen, _readc, _sexit, _getpid, _getargs - .globl _open, _close, _fgetc, _fputc, _flist, _fremove, _pipe + .globl _open, _close, _fgetc, _fputc, _flist, _fremove, _pipe, _ssend, _srecv ;; SDCC sm83 sdcccall(1): 1st arg -> A (byte) or DE (pointer); ret A / BC. ;; rst $30 (the trap) clobbers BC/DE/HL; SDCC treats them caller-saved, so ;; wrappers need not preserve them - but we compute cleanly regardless. @@ -92,6 +92,19 @@ _pipe: rst #0x30 ret + ;; void ssend(unsigned char b /*A*/) -- link-port transmit +_ssend: + ld e, a + ld c, #29 ; SYS_SSEND + rst #0x30 + ret + + ;; unsigned char srecv(void) -> A -- link-port receive (blocks) +_srecv: + ld c, #30 ; SYS_SRECV + rst #0x30 + ret + ;; unsigned char open(const char *name /*DE*/, unsigned char mode /*A*/) -> A(fd) _open: ld b, a ; B = mode -- cgit v1.3.1-sl0p