Lw Instruction Pipeline Activities (In Mips Iii Instruction Mode) - NEC uPD98502 User Manual

2.3.4.5 Load word instruction (LW rt, offset (base))
IF stage Same as the IF stage for the ADD instruction.
IT stage Same as the IT stage for the ADD instruction.
RF stage Same as the RF stage for the ADD instruction. Note that the base field is in the same position
as the rs field.
EX stage Refer to the EX stage for the ADD instruction. For LW, the inputs to the ALU come from
GPR[base] through the bypass multiplexer and from the sign-extended offset field. The result
of the ALU operation that is latched into the ALU output latch in Φ 1 represents the effective
virtual address of the operand (DVA).
DC stage The cache tag field is compared with the Page Frame Number (PFN) field of the TLB entry.
After passing through the load aligner, aligned data is placed in the DC output latch during Φ 2.
During Φ 1, the cache read data is written into the register file addressed by the rt field.
WB stage
Figure 2-17. LW Instruction Pipeline Activities (In MIPS III Instruction Mode)
PClock
Phase
Cycle
92
CHAPTER 2 V
PCycle
Φ 1 Φ 2 Φ 1 Φ 2
IF1 IF2 RF1 RF2
IDC ICA
ITLB ITC IDEC RF
Preliminary User's Manual S15543EJ1V0UM
4120A
R
Φ 1 Φ 2 Φ 1 Φ 2
EX1 EX2 DC1 DC2
EX DCA DL
DVA DTLB DT
Φ 1 Φ 2
WB1 WB2
WB