Sundance-spas ST201 Manual de usuario descargar pdf (Pagina 49)

Sundance Technology ST201 PRELIMINARY draft 2

HASHTABLE

Class....................I/O Registers, Control and Status

Base Address ......IoBaseAddress register value

Address Offset.....0x66, 0x64, 0x62, 0x60

Access Mode.......Read/Write

Width ...................64 bits (accessible as 4, 16 bit words)

The host stores the 64-bit hash table in this register for selectively receiving multicast frames. Setting the

ReceiveMulticastHash bit in ReceiveMode enables the filtering mechanism. The hash table is cleared

upon reset, and must be properly programmed by the host.

The ST201 applies a cyclic-redundancy-check (the same CRC used to calculate the frame data FCS) to

the destination address all incoming multicast frames (with multicast bit set). The low-order 6 bits of the

CRC result are used as an addressing index into the hash table. The MSB of HashTable(3) is the most sig-

nificant, and the LSB of HashTable(0) is the least significant bit, addressed by the 6-bit index. If the Hash-

Table bit addressed by the index is set, the frame is accepted by the ST201 and transferred to higher

layers. If the addressed hash table bit is cleared, the frame is discarded.

BIT BIT NAME BIT DESCRIPTION

15..0 HashTableWord0 The least significant word of the hash table, corresponding to address

0x60.

31..16 HashTableWord1 The second least significant word of the hash table, corresponding to

address 0x62.

47..32 HashTableWord2 The second most significant word of the hash table, corresponding to

address 0x64.

63..48 HashTableWord3 The most significant word of the hash table, corresponding to address

0x66.

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 144 145

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Sundance-spas ST201 Manual de usuario Pagina 49