RX_ELEMENT STRUC
firstCount dw 0 ; # of bytes on 1st call
secondCount dw 0 ; # of bytes on 2nd call
handle dw 0 ; handle for upcall
destinAdr db 6 dup (0) ; packet destination address
sourceAdr db 6 dup (0) ; packet source address
protocol dw 0 ; packet protocol number
rxBuffer db RX_BUF_SIZE dup (0) ; RX buffer
ENDS
align 4
_rxOutOfs dw offset _pktRxBuf ; ring buffer offsets
_rxInOfs dw offset _pktRxBuf ; into _pktRxBuf
_pktDrop dw 0,0 ; packet drop counter
_pktTemp db 20 dup (0) ; temp work area
_pktTxBuf db (TX_BUF_SIZE+14) dup (0) ; TX buffer
_pktRxBuf RX_ELEMENT NUM_RX_BUF dup (<>) ; RX structures
LAST_OFS = offset $
screenSeg dw 0B800h
newInOffset dw 0
fanChars db '-\|/'
fanIndex dw 0
D_END
_TEXT SEGMENT
SHOW_RX MACRO
push es
push bx
mov bx, screenSeg
mov es, bx ;; r-mode segment of colour screen
mov di, 158 ;; upper right corner - 1
mov bx, fanIndex
mov al, fanChars[bx] ;; get write char
mov ah, 15 ;; and white colour
stosw ;; write to screen at ES:EDI
inc fanIndex ;; update next index
and fanIndex, 3
pop bx
pop es
ENDM
;------------------------------------------------------------------------
;
; This macro return ES:DI to tail of Rx queue
ENQUEUE MACRO
LOCAL @noWrap
mov ax, _rxInOfs ;; DI = current in-offset
add ax, SIZE RX_ELEMENT ;; point to next _pktRxBuf buffer
cmp ax, LAST_OFS ;; pointing past last ?
jb @noWrap ;; no - jump
lea ax, _pktRxBuf ;; yes, point to 1st buffer
align 4
@noWrap: cmp ax, _rxOutOfs ;; in-ofs = out-ofs ?
je @dump ;; yes, queue is full
mov di, _rxInOfs ;; ES:DI -> buffer at queue input
mov newInOffset, ax ;; remember new input offset
;; NOTE. rxInOfs is updated after the packet has been copied
;; to ES:DI (= DS:SI on 2nd call) by the packet driver
ENDM
;------------------------------------------------------------------------
;
; This routine gets called by the packet driver twice:
; 1st time (AX=0) it requests an address where to put the packet
;
; 2nd time (AX=1) the packet has been copied to this location (DS:SI)
; BX has client handle (stored in RX_ELEMENT.handle).
; CX has # of bytes in packet on both call. They should be equal.
;
; A test for equality is done by putting CX in _pktRxBuf [n].firstCount
; and _pktRxBuf[n].secondCount, and CL on first call in
; _pktRxBuf[n].rxBuffer[CX]. These values are checked in "PktReceive"
; (PKTDRVR.C)
;
;---------------------------------------------------------------------
_PktReceiver:
pushf
cli ; no distraction wanted !
push ds
push bx
ifdef DOSX
mov bx, cs
else
mov bx, SEG _DATA
endif
mov ds, bx
mov es, bx ; ES = DS = CS or seg _DATA
pop bx ; restore handle
cmp ax, 0 ; first call? (AX=0)
jne @post ; AX=1: second call, do post process
ifdef DEBUG
SHOW_RX ; show that a packet is received
endif
cmp cx, RX_BUF_SIZE+14 ; size OK ?
ja @skip ; no, packet to large for us
ENQUEUE ; ES:DI -> _pktRxBuf[n]
mov [di].firstCount, cx ; remember the first count.
mov [di].handle, bx ; remember the handle.
add di, 6 ; ES:DI -> _pktRxBuf[n].destinAdr
pop ds
popf
retf ; far return to driver with ES:DI
align 4
@dump: inc _pktDrop[0] ; discard the packet on 1st call
adc _pktDrop[2], 0 ; increment packets lost
@skip: xor di, di ; return ES:DI = NIL pointer
xor ax, ax
mov es, ax
pop ds
popf
retf
align 4
@post: or si, si ; DS:SI->_pktRxBuf[n][n].destinAdr
jz @discard ; make sure we don't use NULL-pointer
sub si, 6 ; DS:SI -> _pktRxBuf[n].destinAdr
;
; push si
; push [si].firstCount
; call bpf_filter_match ; run the filter here some day?
; add sp, 4
; cmp ax, 0
; je @discard
