MIPS R4000 Microprocessor User's Manual 183
Floating-Point Unit
MUL.[S,D] can start only when all of the following conditions are met in
the RF stage:
• The multiplier is one of the following:
- idle, or in its second-to-last execution cycle.
- not within the first two execution cycles (EX, EX+1) if the
most recent instruction in the multiplier pipe is MUL.S
- not within the first three execution cycles (EX...EX+2) if
the most recent instruction in the multiplier pipe is
MUL.D
• The adder is one of the following:
- idle, or in its second-to-last execution cycle.
- not processing the first execution cycle (EX) of CVT.S.L
• The adder is not processing a square root instruction
• The divider is one of the following:
- idle, or in its second-to-last execution cycle.
- in the first 8 execution cycles (EX...EX+7) of a DIV.S
- in the first 21 execution cycles, except for the second
execution cycle, (cycles EX, EX+2...EX+20) of a DIV.D)
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