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(*Pipeline for OpenRisc1200Copyright 2004 Ken RoseAll rights reserved*)-Tiscomponent T+IMem +DMem+BusError +TimerIRQ +ExternIRQ +ITLBmiss +DTLBmiss-Iaddr -Daddr -WriteData -WriteEnable -ReadEnablewith(* Pipeline components *)ID_c EX_c MEM_c WB_c RegFile(* Pipeline registers *)IF_ID_PCIF_ID_WriteLinkID_EXID_IRID_EX_RAID_EX_RBID_EX_IRID_EX_MemOffsetID_EX_ALUctlID_EX_CalcFlagID_EX_IMID_EX_UseIMMID_MEM_WriteEnableID_EX_WB_write_whatID_EX_WB_write_enableID_EX_WB_DestID_EX_SPROffsetID_EX_LatchSPRID_EX_PCC V A_fwd B_fwdFlagFlagOutMEM_WB_ALUMEM_WB_IRMEM_WB_write_whatMEM_WB_write_enableMEM_WB_DestMEM_WB_MemAddrMEM_WB_SPRMEM_WB_PCMEM_WB_LatchSPRMEM_WB_BMemInteresting ALUinteresting HIinteresting SPRinteresting A BWriteLinkFetchWasStalled(* Instruction buffer for stalls *)IRbufIRaddrIR(* Stage results *)ID EX MEM WB(* Register file results *)Regs(* SPRs *)EPCR0EEAR0ESR0SREX_WB_SPRindexSPRSPRindexRFEis(* Get the stages *)ID_c <- import "id.cf"EX_c <- import "ex.cf"MEM_c <- import "mem.cf"WB_c <- import "wb.cf"(* And the register file *)RegFile <- import "reg.cf"local TakeBranch BranchTarget StallForFlag StallForBranchDest Stall StallForMem is(* Instruction Fetch *)local NewPC PC Exception ExceptionAddr ExceptionRetPC InSlot is{enable (ID.RunFetch '&' ('~' Stall)) {reg 32 NewPC PC}}Iaddr <- PC{display '0' ({vector_of_string "Iaddr is "$} '++' {hex_of_vector Iaddr $})}{display '0' ({vector_of_string "IRaddr is "$} '++' {hex_of_vector IRaddr.out $})}{display '0' ({vector_of_string "IF_ID_PC is "$} '++' {hex_of_vector IF_ID_PC $})}{display '0' ({vector_of_string "ID_EX_PC is "$} '++' {hex_of_vector ID_EX_PC $})}{display '0' ({vector_of_string "MEM_WB_PC is "$} '++' {hex_of_vector MEM_WB_PC $})}{display '0' ({vector_of_string "Exception is "$} '++' {bin_of_vector Exception $})}{display '0' ({vector_of_string "BusError is "$} '++' {bin_of_vector BusError $})}{display '0' ({vector_of_string "TimerIRQ is "$} '++' {bin_of_vector TimerIRQ $})}{display '0' ({vector_of_string "ExternIRQ is "$} '++' {bin_of_vector ExternIRQ $})}{display '0' ({vector_of_string "ITLBmiss is "$} '++' {bin_of_vector ITLBmiss $})}{display '0' ({vector_of_string "DTLBmiss is "$} '++' {bin_of_vector DTLBmiss $})}{display '0' ({vector_of_string "ID.IllInstr is "$} '++' {bin_of_vector ID.IllInstr $})}{display '0' ({vector_of_string "ID.SysCall is "$} '++' {bin_of_vector ID.SysCall $})}Exception <- BusError '|'TimerIRQ '|'ExternIRQ '|'ITLBmiss '|'DTLBmiss '|'ID.IllInstr '|'ID.SysCallExceptionAddr <- ITLBmiss 'then' '0x00000a00''else' BusError 'then' '0x00000200' (* FIXME distinguish I & D accesses *)'else' ID.IllInstr 'then' '0x00000700''else' DTLBmiss 'then' '0x00000900''else' ID.SysCall 'then' '0x00000c00''else' TimerIRQ 'then' '0x00000500''else' ExternIRQ 'then' '0x00000800''else' '0x00000000' (* Should never happen *)InSlot <- '0'ExceptionRetPC <- ITLBmiss 'then' InSlot 'then' '0x00000a00' 'else' '0x00000a00''else' BusError 'then' InSlot 'then' '0x00000200' 'else' '0x00000200' (* FIXME distinguish I & D accesses *)'else' ID.IllInstr 'then' InSlot 'then' '0x00000700' 'else' '0x00000700''else' DTLBmiss 'then' InSlot 'then' '0x00000900' 'else' '0x00000900''else' ID.SysCall 'then' InSlot 'then' ID_EX_PC 'else' IRaddr.out (* FIXME is this right? *)'else' TimerIRQ 'then' InSlot 'then' '0x00000500' 'else' '0x00000500''else' ExternIRQ 'then' InSlot 'then' '0x00000800' 'else' '0x00000800''else' '0x00000000' (* Should never happen *)NewPC <- {mux (TakeBranch '++' Exception) [(PC '+' '0x00000004')ExceptionAddrBranchTargetExceptionAddr] $}local WriteSR WriteEPCR0 WriteESR0 isWriteEPCR0 <- EX_WB_SPRindex '==' '0x0020' '&' MEM_WB_LatchSPRWriteESR0 <- EX_WB_SPRindex '==' '0x0040' '&' MEM_WB_LatchSPR{reg 32 (Exception 'then' ExceptionRetPC 'else' WriteEPCR0 'then' MEM_WB_B 'else' EPCR0) EPCR0}{display ('0' '&' {regs 1 1 (Exception '|' WriteEPCR0) $}) ({vector_of_string "New EPCR0 is " $} '++' {hex_of_vector EPCR0 $})}{reg 32 (Exception 'then' SR 'else' WriteESR0 'then' MEM_WB_B 'else' ESR0) ESR0}SR <- '0000' (* context *)'++' '00000000000' (* reserved *)'++' '0' (* 16 SUMRA *)'++' '1' (* 15 fixed one *)'++' '0' (* 14 EPH *)'++' '0' (* 13 DSX *)'++' '0' (* 12 OVE *)'++' V (* 11 OV *)'++' C (* 10 CY *)'++' Flag (* 9 F *)'++' '0' (* 8 CE *)'++' '0' (* 7 LEE *)'++' '0' (* 6 IME *)'++' '0' (* 5 DME *)'++' '0' (* 4 ICE *)'++' '0' (* 3 DCE *)'++' '0' (* 2 IEE *)'++' '0' (* 1 TEE *)'++' '0' (* 0 supervisor mode *)C <- {reg 1 (EX.Clatch 'then' EX.Cnew'else' WriteSR 'then' MEM_WB_SPR'[1]'else' RFE 'then' ESR0'[1]'else' C) $}V <- {reg 1 (EX.Vlatch 'then' EX.Vnew'else' WriteSR 'then' MEM_WB_SPR'[2]'else' RFE 'then' ESR0'[2]'else' V) $}WriteSR <- EX_WB_SPRindex '==' '0x0011' '&' MEM_WB_LatchSPREEAR0 <- '0x00000000'end(* Buffer the IMem result for stall handling *)local WasException isIRbuf <- {reg 32 IMem}{enable ('~'FetchWasStalled) IRbuf}IRaddr <- {reg 32 Iaddr}{enable ('~'FetchWasStalled) IRaddr}(* If we're just coming out of a stall, use the buffered instruction,else just use the memory data *)FetchWasStalled <- {reg 1 (('~'ID.RunFetch) '|' Stall) $}WasException <- {reg 1 Exception $}IR <- Exception '|' WasException 'then' '0x15000000' 'else' FetchWasStalled 'then' IRbuf.out 'else' IMem{display '0' ({vector_of_string "IR is " $} '++' {hex_of_vector IR $})}{display '0' ({vector_of_string "ID_IR is " $} '++' {hex_of_vector ID_IR $})}{display '0' ({vector_of_string "ID_EX_IR is " $} '++' {hex_of_vector ID_EX_IR $})}{display '0' ({vector_of_string "MEM_WB_IR is " $} '++' {hex_of_vector MEM_WB_IR $})}{display '0' ({vector_of_string "FetchWasStalled is " $} '++' {bin_of_vector FetchWasStalled $})}endend(* Branch handling *)localBranchOffset NewFlag BranchOpIDMemInteresting IDALUinteresting IDHIinteresting IDSPRinterestingisBranchOffset <- ((IR'[25]) '#' 4) '++' IR'[25:0] '++' '00'WriteLink <- (IR'[31:26] '==' '000001')'|' (IR'[31:26] '==' '010010')NewFlag <- ID.LatchFlag 'then' FlagOut 'else' Flag{display ('0' '&' TakeBranch) ({vector_of_string "Branching, Flag is " $} '++' {bin_of_vector Flag $})}{display ('0' '&' ID.LatchFlag) ({vector_of_string "Flag is " $} '++' {bin_of_vector Flag $})}{display ('0' '&' ID.LatchFlag) ({vector_of_string "NewFlag is " $} '++' {bin_of_vector NewFlag $})}{display ('0' '&' ID.LatchFlag) ({vector_of_string "FlagOut is " $} '++' {bin_of_vector FlagOut $})}{display '0' ({vector_of_string "StallForBranchDest is " $} '++' {bin_of_vector StallForBranchDest $})}TakeBranch <- (IR'[31:26] '==' '000011') '&' ('~' NewFlag)'|' (IR'[31:26] '==' '000100') '&' NewFlag'|' (IR'[31:26] '==' '000000')'|' (IR'[31:26] '==' '000001')'|' (IR'[31:26] '==' '010001')'|' (IR'[31:26] '==' '010010')'|' RFEBranchOp <- (TakeBranch) 'then' IR'[31:28] 'else' {reg 4 (TakeBranch 'then' IR'[31:28] 'else' BranchOp) $}{display '0' ({vector_of_string "Stall is " $} '++' {bin_of_vector (Stall '++' StallForFlag '++' StallForBranchDest '++' StallForMem) $})}Stall <- StallForBranchDest '|' StallForFlag '|' StallForMemStallForMem <- (IR'[20:16] '==' ID_EX_IR'[25:21] '&' IDMemInteresting)'|' (IR'[15:11] '==' ID_EX_IR'[25:21] '&' IDMemInteresting)(* If ID wants to write memory data & IR sets F and ID_IR's dest is IR's source *)StallForFlag <- (ID.WB_write_what '!=' '0000') '&'(ID.WB_write_what '!=' '0111') '&'ID.WB_write_enable '&'((ID_IR'[31:29] '==' '100') '&' (ID_IR'[31:26] '!=' '100111')) '&'(IR'[31:26] '==' '111001') '&'((ID_IR'[25:21] '==' IR'[20:16]) '|' (ID_IR'[25:21] '==' IR'[15:11]))StallForBranchDest <- (TakeBranch'&' (ID.WB_write_enable'&' ( IR'[20:16] '==' ID_IR'[25:21] (* FIXME probably not needed *)'|' IR'[15:11] '==' ID_IR'[25:21]))'|' (IR'[31:28] '==' '0100') '&' '~'FetchWasStalled)(* If IR is a conditional branch & ID_IR changes F *)'|' ((IR'[31:26] '==' '000100' '|' IR'[31:26] '==' '000011')'&' (ID_IR'[31:26] '==' '110000' '|' ID_IR'[31:26] '==' '111001'))IDMemInteresting <- (ID_EX_WB_write_what '!=' '0000') '&' (ID_EX_WB_write_what '!=' '0111') '&' ID_EX_WB_write_enableIDALUinteresting <- (ID_EX_WB_write_what '==' '0000') '&' ID_EX_WB_write_enableIDSPRinteresting <- (ID_EX_WB_write_what '==' '1000') '&' ID_EX_WB_write_enableIDHIinteresting <- (ID_EX_WB_write_what '==' '0111') '&' ID_EX_WB_write_enablelocal DM isDM <- {WB_c.T DMemMEM_WB_ALUMEM_WB_IRMEM_WB_write_whatMEM_WB_MemAddrMEM_WB_SPR$}A_fwd <- ID_IR'[20:16] '==' ID_EX_IR'[25:21] '&' IDALUinteresting 'then' EX.ALU'else' ID_IR'[20:16] '==' ID_EX_IR'[25:21] '&' IDSPRinteresting 'then' MEM_WB_SPR'else' ID_IR'[20:16] '==' ID_EX_IR'[25:21] '&' IDMemInteresting 'then' DM'else' ID_IR'[20:16] '==' ID_EX_IR'[25:21] '&' IDHIinteresting 'then' (ID_EX_IR'[15:0] '++' ('0' '#' 16))'else' ID_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' ALUinteresting 'then' MEM_WB_ALU'else' ID_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' SPRinteresting 'then' MEM_WB_SPR'else' ID_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' MemInteresting 'then' WB.WD'else' ID_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' HIinteresting 'then' (MEM_WB_IR'[15:0] '++' ('0' '#' 16))'else' Regs.ReadPort1B_fwd <- ID_IR'[15:11] '==' ID_EX_IR'[25:21] '&' IDALUinteresting 'then' EX.ALU'else' ID_IR'[15:11] '==' ID_EX_IR'[25:21] '&' IDSPRinteresting 'then' MEM_WB_SPR'else' ID_IR'[15:11] '==' ID_EX_IR'[25:21] '&' IDMemInteresting 'then' DM'else' ID_IR'[15:11] '==' ID_EX_IR'[25:21] '&' IDHIinteresting 'then' (ID_EX_IR'[15:0] '++' ('0' '#' 16))'else' ID_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' ALUinteresting 'then' MEM_WB_ALU'else' ID_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' SPRinteresting 'then' MEM_WB_SPR'else' ID_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' MemInteresting 'then' WB.WD'else' ID_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' HIinteresting 'then' (MEM_WB_IR'[15:0] '++' ('0' '#' 16))'else' Regs.ReadPort2endRFE <- (IR'[31:26] '==' '001001')BranchTarget <- RFE '&' (SPRindex '==' '0x0020') '&' ID_EX_LatchSPR 'then' SPR'else' RFE 'then' EPCR0'else' (BranchOp '==' '0100') 'then' B_fwd'else' (FetchWasStalled 'then' IF_ID_PC 'else' IRaddr.out) '+' BranchOffset{display '0' ({vector_of_string "IDMemInteresting is " $} '++' {bin_of_vector IDMemInteresting $})}{display '0' ({vector_of_string "IDALUinteresting is " $} '++' {bin_of_vector IDALUinteresting $})}{display '0' ({vector_of_string "IDHIinteresting is " $} '++' {bin_of_vector IDHIinteresting $})}{display '0' ({vector_of_string "MemInteresting is " $} '++' {bin_of_vector MemInteresting $})}{display '0' ({vector_of_string "ALUinteresting is " $} '++' {bin_of_vector ALUinteresting $})}{display '0' ({vector_of_string "HIinteresting is " $} '++' {bin_of_vector HIinteresting $})}{display '0' ({vector_of_string "ID_IR'[15:11] is " $} '++' {bin_of_vector ID_IR'[15:11] $})}{display '0' ({vector_of_string "ID_EX_IR'[25:21] is " $} '++' {bin_of_vector ID_EX_IR'[25:21] $})}{display '0' ({vector_of_string "MEM_WB_IR'[25:21] is " $} '++' {bin_of_vector MEM_WB_IR'[25:21] $})}{display '0' ({vector_of_string "B_fwd is " $} '++' {hex_of_vector B_fwd $})}{display '0' ({vector_of_string "A_fwd is " $} '++' {hex_of_vector A_fwd $})}(* Fetch/Decode pipe registers *){regs 32 1 IRaddr.out IF_ID_PC}{regs 1 1 WriteLink IF_ID_WriteLink}(* If we're stalled, force a NOP into the pipe.If we're setting the link reg, force a phony l.add instruction into the pipe. We'll patch in the PC laterOtherwise, move IR down the pipe *)ID_IR <- {reg 32 ({regs 32 0 (StallForFlag '|' StallForMem) $} 'then' IR 'else'{regs 1 1 (('~'ID.RunFetch) '|' StallForBranchDest '|' StallForMem) $} 'then' '0x15000000' 'else'(WriteLink '&' '~'FetchWasStalled) 'then' ('0xe120' '++' IR'[15:11] '++' '00000000000') 'else'IR) $}Flag <- {reg 1 (ID.LatchFlag 'then' FlagOut 'else' Flag) $}FlagOut <- {mux ID.CalcFlag [(* 0000 l.sfeq *) (A_fwd '==' B_fwd)(* 0001 l.sfne *) (A_fwd '!=' B_fwd)(* 0010 l.sfgtu *) (A_fwd '>' B_fwd)(* 0011 l.sfgeu *) (A_fwd '>=' B_fwd)(* 0100 l.sfltu *) (A_fwd '<' B_fwd)(* 0101 l.sfleu *) (A_fwd '<=' B_fwd)(* 0110 *) '0'(* 0111 *) '0'(* 1000 *) '0'(* 1001 *) '0'(* 1010 l.sfgts *) (A_fwd '>+' B_fwd)(* 1011 l.sfges *) (A_fwd '>=+' B_fwd)(* 1100 l.sflts *) (A_fwd '<+' B_fwd)(* 1101 l.sfles *) (A_fwd '<=+' B_fwd)(* 1110 *) '0'(* 1111 *) '0'] $}endend(* Instruction Decode *)ID <- {ID_c.T ID_IR }(* the register file *)local RegA RegB isRegA <- FetchWasStalled 'then' IR'[20:16] 'else' ID_IR'[20:16]RegB <- FetchWasStalled 'then' IR'[15:11] 'else' ID_IR'[15:11]Regs <- {RegFile.T WB.WD MEM_WB_Dest MEM_WB_write_enable RegA RegB}end(* Execute *)component ID_EX isID_EX_RA <- {reg 32 (IF_ID_WriteLink 'then' ({regs 1 2 FetchWasStalled $} 'then' MEM_WB_PC 'else' IF_ID_PC) 'else' Regs.ReadPort1) $}{display '0' ({vector_of_string "ID_EX_RA " $} '++' {hex_of_vector ID_EX_RA $})}ID_EX_RB <- {reg 32 (IF_ID_WriteLink 'then''0x00000008' 'else' Regs.ReadPort2) $}{display '0' ({vector_of_string "ID_EX_RB " $} '++' {hex_of_vector ID_EX_RB $})}ID_EX_IM <- {reg 32 ID.IM $}ID_EX_UseIMM <- {reg 1 ID.UseIMM $}ID_EX_IR <- {regs 32 1 ID_IR $}ID_EX_MemOffset <- {reg 32 ID.MemOffset $}ID_EX_ALUctl <- {regs (width ID.ALUctl) 1 ID.ALUctl $}ID_EX_CalcFlag <- {regs (width ID.CalcFlag) 1 ID.CalcFlag $}ID_MEM_WriteEnable <- {regs 2 1 ID.MEMWriteEnable $}ID_EX_WB_write_what <- {regs (width ID.WB_write_what) 1 ID.WB_write_what $}ID_EX_WB_write_enable <- {regs 1 1 ID.WB_write_enable $}ID_EX_WB_Dest <- {regs 5 1 ID.WB_Dest $}ID_EX_SPROffset <- {regs (width ID.SPROffset) 1 ID.SPROffset $}ID_EX_LatchSPR <- {regs 1 1 ID.LatchSPR $}ID_EX_PC <- {regs 32 1 IF_ID_PC $}end{enable '1' {ID_EX}}MemInteresting <- (MEM_WB_write_what '!=' '0000') '&' (MEM_WB_write_what '!=' '0111') '&' MEM_WB_write_enableSPRinteresting <- (MEM_WB_write_what '==' '1000') '&' MEM_WB_write_enableALUinteresting <- (MEM_WB_write_what '==' '0000') '&' MEM_WB_write_enableHIinteresting <- (MEM_WB_write_what '==' '0111') '&' MEM_WB_write_enableA <- ID_EX_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' ALUinteresting 'then' MEM_WB_ALU'else' ID_EX_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' SPRinteresting 'then' MEM_WB_SPR'else' ID_EX_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' MemInteresting 'then' WB.WD'else' ID_EX_IR'[20:16] '==' MEM_WB_IR'[25:21] '&' HIinteresting 'then' (MEM_WB_IR'[15:0] '++' ('0' '#' 16))'else' ID_EX_RAB <- ID_EX_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' ALUinteresting 'then' MEM_WB_ALU'else' ID_EX_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' SPRinteresting 'then' MEM_WB_SPR'else' ID_EX_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' MemInteresting 'then' WB.WD'else' ID_EX_IR'[15:11] '==' MEM_WB_IR'[25:21] '&' HIinteresting 'then' (MEM_WB_IR'[15:0] '++' ('0' '#' 16))'else' ID_EX_RBEX <- {EX_c.T ID_EX_ALUctlID_EX_IRA(ID_EX_UseIMM 'then' ID_EX_IM 'else' B)C}(* Memory Access *)MEM <- {MEM_c.T BID_MEM_WriteEnable(ID_EX_MemOffset '+' A)}local SPRreg SPRgroup isSPRindex <- A'[15:0] '|' ID_EX_SPROffsetSPRreg <- SPRindex'[11:0]SPRgroup <- SPRindex'[15:12](*0 32 0020 EPCR0 - r/w Exception PC0 48 0030 EEAR0 - r/w Exception EA0 64 0040 ESR0 - r/w Exception SR*)(*0 0 0000 VR - r version reg.0 1 0001 UPR - r unit present0 2 0002 CPUCFGR - r CPU configuration0 3 0003 DMMUCFGR - r Data MMU configuration0 4 0004 IMMUCFGR - r Instruction MMU config,0 5 0005 DCCFGR - r Data cache configuration0 6 0006 ICCFGR - r Instruction cache config0 7 0007 DCFGR - r Debug configuration0 8 0008 PCCFGR - r Performance counter config0 16 0010 NPC - r/w PC mapped to SPR space (next PC)0 17 0011 SR - r/w Supervision reg.0 18 0012 PPC - r/w PC mapped to SPR space (prev PC)0 32 0020 EPCR0 - r/w Exception PC0 48 0030 EEAR0 - r/w Exception EA0 64 0040 ESR0 - r/w Exception SR*)SPR <- SPRindex '==' '0x0000' 'then' '0x12cf0000' (* VR *)'else' SPRindex '==' '0x0001' 'then' '0x00000001' (* UPR, for now *)'else' SPRindex '==' '0x0002' 'then' '0x00000020' (* CPUCFGR *)'else' SPRindex '==' '0x0003' 'then' '0x00000000' (* DMMUCFGR *)'else' SPRindex '==' '0x0004' 'then' '0x00000000' (* IMMUCFGR *)'else' SPRindex '==' '0x0005' 'then' '0x00000000' (* DCCFGR *)'else' SPRindex '==' '0x0006' 'then' '0x00000000' (* ICCFGR *)'else' SPRindex '==' '0x0007' 'then' '0x00000000' (* DCFGR *)'else' SPRindex '==' '0x0008' 'then' '0x00000000' (* PCCFGR *)'else' SPRindex '==' '0x0010' 'then' IF_ID_PC (* NPC *)'else' SPRindex '==' '0x0011' 'then' SR (* SR *)'else' SPRindex '==' '0x0012' 'then' MEM_WB_PC (* PPC *)'else' SPRindex '==' '0x0020' 'then' EPCR0 (* EPCR0 *)'else' SPRindex '==' '0x0030' 'then' EEAR0 (* EEAR0 *)'else' SPRindex '==' '0x0040' 'then' ESR0 (* ESR0 *)'else' '0x00000000' (* all others *)MEM_WB_SPR <- {reg 32 SPR $}MEM_WB_B <- {reg 32 B $}EX_WB_SPRindex <- {reg 16 SPRindex $}end(* Exports from the core to the memory system *)Daddr <- MEM.Addr'[31:2] '++' '00'WriteData <- MEM.DataWriteEnable <- MEM.WriteEnable(* We actually care about the memory data only* if the writeback mux will select it *)ReadEnable <- '~'(ID_EX_WB_write_what '==' '0000''|' ID_EX_WB_write_what '==' '0111''|' ID_EX_WB_write_what '==' '1000')(* Final stage latches (EX/WB) *)MEM_WB_ALU <- {reg 32 EX.ALU $}MEM_WB_IR <- {reg 32 ID_EX_IR $}MEM_WB_write_what <- {regs (width ID_EX_WB_write_what) 1 ID_EX_WB_write_what $}MEM_WB_write_enable <- {reg 1 ID_EX_WB_write_enable $}MEM_WB_Dest <- {reg 5 ID_EX_WB_Dest $}MEM_WB_MemAddr <- {reg 32 MEM.Addr $}MEM_WB_PC <- {regs 32 1 ID_EX_PC $}MEM_WB_LatchSPR <- {regs 1 1 ID_EX_LatchSPR $}(* Register Writeback *)WB <- {WB_c.T DMemMEM_WB_ALUMEM_WB_IRMEM_WB_write_whatMEM_WB_MemAddrMEM_WB_SPR}end