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5.36MACHashAddressRegister1(MACHASH1)
5.37MACHashAddressRegister2(MACHASH2)
EthernetMediaAccessController(EMAC)Registers
TheMAChashregistersallowgroupaddressedframestobeacceptedonthebasisofahashfunction
oftheaddress.Thehashfunctioncreatesa6-bitdatavalue(Hash_fun)fromthe48-bitdestination
address(DA)asfollows:
Hash_fun(0)=DA(0)XORDA(6)XORDA(12)XORDA(18)XORDA(24)XORDA(30)XORDA(36)XORDA(42);
Hash_fun(1)=DA(1)XORDA(7)XORDA(13)XORDA(19)XORDA(25)XORDA(31)XORDA(37)XORDA(43);
Hash_fun(2)=DA(2)XORDA(8)XORDA(14)XORDA(20)XORDA(26)XORDA(32)XORDA(38)XORDA(44);
Hash_fun(3)=DA(3)XORDA(9)XORDA(15)XORDA(21)XORDA(27)XORDA(33)XORDA(39)XORDA(45);
Hash_fun(4)=DA(4)XORDA(10)XORDA(16)XORDA(22)XORDA(28)XORDA(34)XORDA(40)XORDA(46);
Hash_fun(5)=DA(5)XORDA(11)XORDA(17)XORDA(23)XORDA(29)XORDA(35)XORDA(41)XORDA(47);
Thisfunctionisusedasanoffsetintoa64-bithashtablestoredinMACHASH1andMACHASH2that
indicateswhetheraparticularaddressshouldbeacceptedornot.
TheMAChashaddressregister1(MACHASH1)isshowninFigure62anddescribedinTable61.
Figure62.MACHashAddressRegister1(MACHASH1)
3116
MACHASH1
R/W-0
150
MACHASH1
R/W-0
LEGEND:R=Readonly;R/W=Read/Write;-n=valueafterreset
Table61.MACHashAddressRegister1(MACHASH1)FieldDescriptions
BitFieldValueDescription
31-0MACHASH10-FFFFFFFFhLeast-significant32bitsofthehashtablecorrespondingtohashvalues0to31.Ifahash
tablebitisset,thenagroupaddressthathashestothatbitindexisaccepted.
TheMAChashaddressregister2(MACHASH2)isshowninFigure63anddescribedinTable62.
Figure63.MACHashAddressRegister2(MACHASH2)
3116
MACHASH2
R/W-0
150
MACHASH2
R/W-0
LEGEND:R=Readonly;R/W=Read/Write;-n=valueafterreset
Table62.MACHashAddressRegister2(MACHASH2)FieldDescriptions
BitFieldValueDescription
31-0MACHASH20-FFFFFFFFhMost-significant32bitsofthehashtablecorrespondingtohashvalues32to63.Ifahash
tablebitisset,thenagroupaddressthathashestothatbitindexisaccepted.
SPRU941A–April2007EthernetMediaAccessController(EMAC)/101
ManagementDataInput/Output(MDIO)
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