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-rw-r--r--src/boot.asm1
-rw-r--r--src/socket.asm754
-rw-r--r--src/syscall.asm1
3 files changed, 756 insertions, 0 deletions
diff --git a/src/boot.asm b/src/boot.asm
index 23511c4..c29267d 100644
--- a/src/boot.asm
+++ b/src/boot.asm
@@ -56,6 +56,7 @@ KernelInit:
ld a, HIGH(wKernelPCB)
ld [wCurProc+1], a
call pipe_init ; mark all pipes free
+ call net_init ; clear the socket table, set our IP (10.0.0.2)
call fs_init ; mount the disk (format on first boot; persists)
call term_init ; set up the LCD text terminal
call osk_init ; build the on-screen keyboard (window layer)
diff --git a/src/socket.asm b/src/socket.asm
new file mode 100644
index 0000000..f0d8444
--- /dev/null
+++ b/src/socket.asm
@@ -0,0 +1,754 @@
+; =============================================================================
+; socket.asm - the kernel network stack + socket layer (SYS_NET).
+;
+; The kernel owns the link port: SLIP framing, IPv4, checksums, and the per-
+; protocol logic all live here. Userland just does socket()/connect()/send()/
+; recv()/close() via one syscall (DE = &netreq). No program touches SLIP or IP.
+;
+; Our address is 10.0.0.2. Incoming ICMP echo requests are auto-answered while
+; any process pumps RX (recv/poll), so the Game Boy responds to pings for real.
+;
+; Phase 1: ICMP (echo). UDP and TCP build on the same frame/checksum core.
+; =============================================================================
+INCLUDE "include/gbos.inc"
+
+; ---- socket entry layout ----------------------------------------------------
+DEF SK_TYPE EQU 0 ; 0 = free
+DEF SK_RIP EQU 1 ; 4 remote IP
+DEF SK_RPORT EQU 5 ; 2 remote port
+DEF SK_LPORT EQU 7 ; 2 local port
+DEF SK_HASRX EQU 9 ; 1 rxbuf holds a datagram
+DEF SK_RXLEN EQU 10 ; 1 payload length
+DEF SK_SRCIP EQU 11 ; 4 sender IP
+DEF SK_SRCPORT EQU 15 ; 2 sender port
+DEF SK_RXBUF EQU 17 ; 96 payload
+DEF SK_SIZE EQU 113
+
+SECTION "net_bss", WRAM0
+wSockTab:: DS MAX_SOCKS * SK_SIZE
+wNetOurIP:: DS 4
+wNetReq:: DS NR_SIZE
+wNetSockPtr:: DS 2
+wNetIhl:: DS 1
+wNetSeq:: DS 1
+wNetTx:: DS 256 ; tx build buffer
+wNetRxBuf:: DS 256 ; rx frame assembly / parse
+wNetRxLen:: DS 1
+wNetRxEsc:: DS 1
+
+SECTION "socket", ROM0
+
+; net_init - clear the socket table and set our IP (called at boot).
+net_init::
+ ld hl, wSockTab
+ ld bc, MAX_SOCKS * SK_SIZE
+.clr
+ xor a
+ ld [hl+], a
+ dec bc
+ ld a, b
+ or c
+ jr nz, .clr
+ ld a, 10
+ ld [wNetOurIP+0], a
+ xor a
+ ld [wNetOurIP+1], a
+ ld [wNetOurIP+2], a
+ ld a, 2
+ ld [wNetOurIP+3], a
+ xor a
+ ld [wNetRxLen], a
+ ld [wNetRxEsc], a
+ ld [wNetSeq], a
+ ret
+
+; -----------------------------------------------------------------------------
+; low-level link port (byte at a time). Preserve BC/DE/HL; use A only.
+net_putbyte: ; A = byte to transmit
+ ld [rSB], a
+ ld a, $81
+ ld [rSC], a
+.w
+ ld a, [rSC]
+ bit 7, a
+ jr nz, .w
+ ret
+
+net_getbyte_nb: ; -> A = byte, CF set if none
+ ld a, $80
+ ld [rSC], a
+ ld a, [rSC]
+ bit 7, a
+ jr z, .got
+ scf
+ ret
+.got
+ ld a, [rSB]
+ and a ; CF = 0
+ ret
+
+; -----------------------------------------------------------------------------
+; net_slip_send(HL = buf, B = len) - transmit a SLIP frame.
+net_slip_send:
+ ld a, SLIP_END
+ call net_putbyte
+.loop
+ ld a, b
+ or a
+ jr z, .end
+ ld a, [hl+]
+ cp SLIP_END
+ jr z, .esc_end
+ cp SLIP_ESC
+ jr z, .esc_esc
+ call net_putbyte
+.cont
+ dec b
+ jr .loop
+.esc_end
+ ld a, SLIP_ESC
+ call net_putbyte
+ ld a, SLIP_ESC_END
+ call net_putbyte
+ jr .cont
+.esc_esc
+ ld a, SLIP_ESC
+ call net_putbyte
+ ld a, SLIP_ESC_ESC
+ call net_putbyte
+ jr .cont
+.end
+ ld a, SLIP_END
+ call net_putbyte
+ ret
+
+; -----------------------------------------------------------------------------
+; net_cksum(HL = buf, B = len, DE = seed) -> HL = inverted 16-bit checksum.
+; One's-complement sum (RFC 1071), carry-folded each add. len <= 255.
+net_cksum:
+.loop
+ ld a, b
+ cp 2
+ jr c, .tail
+ ld a, [hl+] ; high byte
+ ld c, a
+ ld a, [hl+] ; low byte
+ add e
+ ld e, a
+ ld a, c
+ adc d
+ ld d, a
+ jr nc, .nc1
+ inc de
+.nc1
+ dec b
+ dec b
+ jr .loop
+.tail
+ ld a, b
+ or a
+ jr z, .fold
+ ld a, [hl] ; last odd byte -> high half
+ add d
+ ld d, a
+ jr nc, .fold
+ inc e
+ jr nz, .fold
+ inc d
+.fold
+ ld a, d
+ cpl
+ ld h, a
+ ld a, e
+ cpl
+ ld l, a
+ ret
+
+; -----------------------------------------------------------------------------
+; net_sock_ptr(A = sockid) -> HL = &wSockTab[A] (clobbers B, DE)
+net_sock_ptr:
+ ld hl, wSockTab
+ or a
+ ret z
+ ld b, a
+ ld de, SK_SIZE
+.l
+ add hl, de
+ dec b
+ jr nz, .l
+ ret
+
+; =============================================================================
+; sys_net(DE = &netreq) -> A = result
+; =============================================================================
+sys_net::
+ ld hl, wNetReq ; copy the request out of process RAM
+ ld b, NR_SIZE
+.cp
+ ld a, [de]
+ ld [hl+], a
+ inc de
+ dec b
+ jr nz, .cp
+ ld a, [wNetReq + NR_OP]
+ cp NET_SOCKET
+ jp z, net_op_socket
+ cp NET_CONNECT
+ jp z, net_op_connect
+ cp NET_SEND
+ jp z, net_op_send
+ cp NET_RECV
+ jp z, net_op_recv
+ cp NET_CLOSE
+ jp z, net_op_close
+ cp NET_POLL
+ jp z, net_op_poll
+ ld a, $FF
+ ret
+
+; ---- socket(type) -> A = sockid or $FF ---------------------------------------
+net_op_socket:
+ ld c, 0
+.scan
+ ld a, c
+ call net_sock_ptr ; HL = &sock[c]
+ ld a, [hl]
+ or a ; SK_TYPE == 0 (free)?
+ jr z, .free
+ inc c
+ ld a, c
+ cp MAX_SOCKS
+ jr c, .scan
+ ld a, $FF ; table full
+ ret
+.free
+ ld a, [wNetReq + NR_SOCK] ; requested type
+ ld [hl], a ; SK_TYPE
+ ld a, l ; clear SK_HASRX
+ add SK_HASRX
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ xor a
+ ld [hl], a
+ ld a, c ; return sockid
+ ret
+
+; ---- connect(sock, ip, port) - set remote --------------------------------
+net_op_connect:
+ ld a, [wNetReq + NR_SOCK]
+ call net_sock_ptr ; HL = &sock
+ ld a, l
+ add SK_RIP
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a ; HL = &sock.RIP
+ ld de, wNetReq + NR_IP
+ ld b, 6 ; 4 IP + 2 port (contiguous: RIP then RPORT)
+.cp
+ ld a, [de]
+ ld [hl+], a
+ inc de
+ dec b
+ jr nz, .cp
+ xor a
+ ret
+
+; ---- close(sock) -------------------------------------------------------------
+net_op_close:
+ ld a, [wNetReq + NR_SOCK]
+ call net_sock_ptr
+ xor a
+ ld [hl], a ; SK_TYPE = free
+ ret
+
+; ---- poll - pump RX once (answers pings) -------------------------------------
+net_op_poll:
+ call net_pump
+ xor a
+ ret
+
+; ---- send(sock, buf, len) ----------------------------------------------------
+net_op_send:
+ ld a, [wNetReq + NR_SOCK]
+ call net_sock_ptr
+ ld a, l
+ ld [wNetSockPtr], a
+ ld a, h
+ ld [wNetSockPtr+1], a
+ ld a, [hl] ; SK_TYPE
+ cp SOCK_ICMP
+ jp z, icmp_send
+ ld a, $FF
+ ret
+
+; ---- recv(sock, buf, maxlen) -> A = len or $FF (timeout) ---------------------
+net_op_recv:
+ ld a, [wNetReq + NR_SOCK]
+ call net_sock_ptr
+ ld a, l
+ ld [wNetSockPtr], a
+ ld a, h
+ ld [wNetSockPtr+1], a
+ ld b, 200 ; outer timeout
+.outer
+ ld de, 0
+.inner
+ call net_pump
+ call sock_has_rx ; Z clear (nz) if HASRX set
+ jr nz, .got
+ dec de
+ ld a, d
+ or e
+ jr nz, .inner
+ call SchedYield
+ dec b
+ jr nz, .outer
+ ld a, $FF ; timeout
+ ret
+.got
+ ; copy sock.RXBUF -> process NR_BUF, len = sock.RXLEN, NR_IP = sock.SRCIP
+ call sock_ptr_hl ; HL = &sock
+ push hl
+ ld a, l
+ add SK_RXLEN
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ ld a, [hl] ; RXLEN
+ ld c, a ; C = length
+ pop hl
+ ; source IP -> wNetReq.NR_IP (returned to caller via buffer? no - copy to caller req is skipped; give src via NR_IP in kernel copy only)
+ push bc
+ push hl
+ ; dst = process buf pointer
+ ld a, [wNetReq + NR_BUF]
+ ld e, a
+ ld a, [wNetReq + NR_BUF + 1]
+ ld d, a ; DE = process buf
+ ld a, l
+ add SK_RXBUF
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a ; HL = &sock.RXBUF
+ ld a, c
+ or a
+ jr z, .nocopy
+.cpl
+ ld a, [hl+]
+ ld [de], a
+ inc de
+ dec c
+ jr nz, .cpl
+.nocopy
+ pop hl ; &sock
+ pop bc ; C = length
+ ; clear HASRX
+ ld a, l
+ add SK_HASRX
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ xor a
+ ld [hl], a
+ ld a, c ; return length
+ ret
+
+; sock_ptr_hl -> HL = current socket pointer (from wNetSockPtr)
+sock_ptr_hl:
+ ld a, [wNetSockPtr]
+ ld l, a
+ ld a, [wNetSockPtr+1]
+ ld h, a
+ ret
+
+; sock_has_rx -> Z clear (nz) if the current socket has a buffered datagram
+sock_has_rx:
+ call sock_ptr_hl
+ ld a, l
+ add SK_HASRX
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ ld a, [hl]
+ or a
+ ret
+
+; =============================================================================
+; icmp_send - build + transmit an ICMP echo request from the current socket.
+; =============================================================================
+icmp_send:
+ ; IP header (20 bytes)
+ ld a, $45
+ ld [wNetTx+0], a
+ xor a
+ ld [wNetTx+1], a
+ ld [wNetTx+2], a ; total len hi
+ ld a, [wNetReq+NR_LEN]
+ add 28
+ ld [wNetTx+3], a ; total len lo = 28 + payload
+ xor a
+ ld [wNetTx+4], a
+ ld [wNetTx+5], a ; id
+ ld [wNetTx+6], a
+ ld [wNetTx+7], a ; flags/frag
+ ld a, 64
+ ld [wNetTx+8], a ; ttl
+ ld a, 1
+ ld [wNetTx+9], a ; proto ICMP
+ xor a
+ ld [wNetTx+10], a
+ ld [wNetTx+11], a ; ip cksum
+ ld a, [wNetOurIP+0]
+ ld [wNetTx+12], a
+ ld a, [wNetOurIP+1]
+ ld [wNetTx+13], a
+ ld a, [wNetOurIP+2]
+ ld [wNetTx+14], a
+ ld a, [wNetOurIP+3]
+ ld [wNetTx+15], a
+ ; dst IP = sock.RIP
+ call sock_ptr_hl
+ ld a, l
+ add SK_RIP
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a ; HL = &sock.RIP
+ ld de, wNetTx+16
+ ld b, 4
+.dip
+ ld a, [hl+]
+ ld [de], a
+ inc de
+ dec b
+ jr nz, .dip
+ ; ICMP header (8 bytes) at wNetTx+20
+ ld a, 8
+ ld [wNetTx+20], a ; type = echo request
+ xor a
+ ld [wNetTx+21], a ; code
+ ld [wNetTx+22], a
+ ld [wNetTx+23], a ; cksum
+ ld a, $12
+ ld [wNetTx+24], a ; id
+ ld a, $34
+ ld [wNetTx+25], a
+ xor a
+ ld [wNetTx+26], a ; seq hi
+ ld a, [wNetSeq]
+ inc a
+ ld [wNetSeq], a
+ ld [wNetTx+27], a ; seq lo
+ ; payload from process buf
+ ld a, [wNetReq+NR_BUF]
+ ld l, a
+ ld a, [wNetReq+NR_BUF+1]
+ ld h, a
+ ld de, wNetTx+28
+ ld a, [wNetReq+NR_LEN]
+ ld b, a
+ or a
+ jr z, .nopl
+.cppl
+ ld a, [hl+]
+ ld [de], a
+ inc de
+ dec b
+ jr nz, .cppl
+.nopl
+ ; ICMP checksum over 8 + payload
+ ld a, [wNetReq+NR_LEN]
+ add 8
+ ld b, a
+ ld hl, wNetTx+20
+ ld de, 0
+ call net_cksum
+ ld a, h
+ ld [wNetTx+22], a
+ ld a, l
+ ld [wNetTx+23], a
+ ; IP checksum over 20
+ ld hl, wNetTx
+ ld b, 20
+ ld de, 0
+ call net_cksum
+ ld a, h
+ ld [wNetTx+10], a
+ ld a, l
+ ld [wNetTx+11], a
+ ; transmit: 28 + payload
+ ld a, [wNetReq+NR_LEN]
+ add 28
+ ld b, a
+ ld hl, wNetTx
+ call net_slip_send
+ xor a
+ ret
+
+; =============================================================================
+; net_pump - read available serial bytes, assemble SLIP frames, process each.
+; Non-blocking: returns when the link has no more bytes ready.
+; =============================================================================
+net_pump:
+.next
+ call net_getbyte_nb
+ ret c ; no byte ready
+ ; SLIP decode using wNetRxLen / wNetRxEsc
+ cp SLIP_END
+ jr z, .frame
+ ld c, a ; save byte
+ ld a, [wNetRxEsc]
+ or a
+ jr nz, .escaped
+ ld a, c
+ cp SLIP_ESC
+ jr z, .setesc
+ jr .store
+.escaped
+ ld a, c
+ cp SLIP_ESC_END
+ jr nz, .notend
+ ld c, SLIP_END
+.notend
+ ld a, c
+ cp SLIP_ESC_ESC
+ jr nz, .noteesc
+ ld c, SLIP_ESC
+.noteesc
+ xor a
+ ld [wNetRxEsc], a
+ ld a, c
+ jr .store2
+.setesc
+ ld a, 1
+ ld [wNetRxEsc], a
+ jr .next
+.store
+ ld a, c
+.store2
+ ; store A at wNetRxBuf[wNetRxLen] if room
+ ld c, a
+ ld a, [wNetRxLen]
+ cp 255
+ jr nc, .next ; overflow: drop
+ ld e, a
+ ld d, 0
+ ld hl, wNetRxBuf
+ add hl, de
+ ld a, c
+ ld [hl], a
+ ld a, [wNetRxLen]
+ inc a
+ ld [wNetRxLen], a
+ jr .next
+.frame
+ ; END: if we have a frame, process it
+ xor a
+ ld [wNetRxEsc], a
+ ld a, [wNetRxLen]
+ or a
+ jr z, .next ; empty frame
+ push bc
+ call process_frame
+ pop bc
+ xor a
+ ld [wNetRxLen], a
+ jr .next
+
+; -----------------------------------------------------------------------------
+; process_frame - IPv4 demux of the frame in wNetRxBuf (wNetRxLen bytes).
+process_frame:
+ ld a, [wNetRxBuf]
+ and $F0
+ cp $40
+ ret nz ; not IPv4
+ ld a, [wNetRxBuf]
+ and $0F
+ add a, a
+ add a, a
+ ld [wNetIhl], a ; ihl in bytes
+ ld a, [wNetRxBuf+9] ; protocol
+ cp 1
+ jr z, icmp_in
+ ret
+
+; -----------------------------------------------------------------------------
+; icmp_in - handle an inbound ICMP message.
+icmp_in:
+ ld a, [wNetIhl]
+ ld e, a
+ ld d, 0
+ ld hl, wNetRxBuf
+ add hl, de ; HL = &icmp
+ ld a, [hl] ; type
+ cp 8
+ jr z, icmp_request
+ or a ; type 0 = echo reply
+ jr z, icmp_reply
+ ret
+
+; incoming echo request -> answer it in place
+icmp_request:
+ ld a, [wNetIhl]
+ ld e, a
+ ld d, 0
+ ld hl, wNetRxBuf
+ add hl, de ; HL = &icmp
+ xor a
+ ld [hl+], a ; type = 0
+ inc hl ; skip code
+ xor a
+ ld [hl+], a
+ ld [hl], a ; cksum = 0
+ call net_swap_ip
+ ; icmp cksum over (rxlen - ihl)
+ ld a, [wNetIhl]
+ ld e, a
+ ld d, 0
+ ld hl, wNetRxBuf
+ add hl, de ; HL = &icmp
+ ld a, [wNetRxLen]
+ sub e
+ ld b, a
+ ld de, 0
+ push hl
+ call net_cksum ; HL = cksum
+ pop de ; DE = &icmp
+ ld a, e
+ add 2
+ ld e, a
+ ld a, d
+ adc 0
+ ld d, a ; DE = &icmp+2
+ ld a, h
+ ld [de], a
+ inc de
+ ld a, l
+ ld [de], a
+ ; IP cksum
+ xor a
+ ld [wNetRxBuf+10], a
+ ld [wNetRxBuf+11], a
+ ld a, [wNetIhl]
+ ld b, a
+ ld hl, wNetRxBuf
+ ld de, 0
+ call net_cksum
+ ld a, h
+ ld [wNetRxBuf+10], a
+ ld a, l
+ ld [wNetRxBuf+11], a
+ ; send it back
+ ld a, [wNetRxLen]
+ ld b, a
+ ld hl, wNetRxBuf
+ call net_slip_send
+ ret
+
+; incoming echo reply -> deliver to the first ICMP socket
+icmp_reply:
+ ld c, 0
+.scan
+ ld a, c
+ call net_sock_ptr ; HL = &sock
+ ld a, [hl]
+ cp SOCK_ICMP
+ jr z, .deliver
+ inc c
+ ld a, c
+ cp MAX_SOCKS
+ jr c, .scan
+ ret ; no ICMP socket
+.deliver
+ ; HL = &sock. payload = wNetRxBuf + ihl + 8, len = rxlen - ihl - 8
+ push hl
+ ; set HASRX = 1
+ ld a, l
+ add SK_HASRX
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ ld a, 1
+ ld [hl], a
+ pop hl
+ ; SRCIP = wNetRxBuf[12..15]
+ push hl
+ ld a, l
+ add SK_SRCIP
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ ld de, wNetRxBuf+12
+ ld b, 4
+.sip
+ ld a, [de]
+ ld [hl+], a
+ inc de
+ dec b
+ jr nz, .sip
+ pop hl
+ ; RXLEN + RXBUF
+ ld a, [wNetIhl]
+ add 8
+ ld e, a
+ ld d, 0 ; DE = ihl+8 (payload offset)
+ ld a, [wNetRxLen]
+ sub e
+ ld c, a ; C = payload length
+ push hl
+ ld a, l
+ add SK_RXLEN
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a
+ ld a, c
+ ld [hl], a ; RXLEN
+ pop hl
+ ; copy payload
+ ld a, l
+ add SK_RXBUF
+ ld l, a
+ ld a, h
+ adc 0
+ ld h, a ; HL = &sock.RXBUF (dest)
+ push hl
+ ld hl, wNetRxBuf
+ add hl, de ; HL = &payload (src)
+ pop de ; DE = dest
+ ld a, c
+ or a
+ ret z
+.cp
+ ld a, [hl+]
+ ld [de], a
+ inc de
+ dec c
+ jr nz, .cp
+ ret
+
+; net_swap_ip - swap the src/dst IP fields of the frame in wNetRxBuf
+net_swap_ip:
+ ld hl, wNetRxBuf+12
+ ld de, wNetRxBuf+16
+ ld b, 4
+.l
+ ld a, [hl]
+ ld c, a
+ ld a, [de]
+ ld [hl+], a
+ ld a, c
+ ld [de], a
+ inc de
+ dec b
+ jr nz, .l
+ ret
diff --git a/src/syscall.asm b/src/syscall.asm
index f926d89..5b40ef0 100644
--- a/src/syscall.asm
+++ b/src/syscall.asm
@@ -67,6 +67,7 @@ SyscallTable:
dw sys_srecv ; 30 SRECV
dw sys_srecv_nb ; 31 SRECVNB
dw sys_pollin ; 32 POLLIN
+ dw sys_net ; 33 NET
; -----------------------------------------------------------------------------
sys_nosys:
generated by cgit v1.3.1-sl0p (git 2.54.0) at 2026-07-21 20:53:32 +0000 — sl0p fork