SMC Networks SMC91C95 - Manual (Page 73)

73
FIGURE 10 - ETHERNET INTERRUPT SERVICE ROUTINE
ISR
Save Bank Select & Address
Ptr Registers
Mask 91C94 Interrupts
Read Interrupt Register
Call TX INTR or TXEMPTY
INTR
TX INTR?
Get Next TX
RX INTR?
Yes
No
No Yes
Call RXINTR
ALLOC INTR?
No Yes
Write Allocated Pkt # into
Packet Number Reg.
Write Ad Ptr Reg. & Copy Data
& Source Address
Enqueue Packet
Packet
Available for
Transmission? Yes No
Call ALLOCATE
EPH INTR?
No Yes
Call EPH INTR
Set "Ready for Packet" Flag
Return Buffers to Upper Layer
Disable Allocation Interrupt
Mask
Restore Address Pointer &
Bank Select Registers
Unmask 91C94 Interrupts
Exit ISR