MIPS R4000 Microprocessor User's Manual 185
Floating-Point Unit
ADD.[S,D], SUB.[S,D] or C.COND.[S,D] can only start when all of the
following conditions are met in the RF stage:
• The adder is either idle, or in its second-to-last execution cycle.
• The multiplier is one of the following:
- idle, or in its second-to-last execution cycle.
- not in the third or fourth execution cycles (EX+2...EX+3)
if the most recent instruction in the multiplier pipe is
MUL.S
- not in the fourth or fifth execution cycles (EX+3...EX+4) if
the most recent instruction in the multiplier pipe is
MUL.D
• The divider is one of the following:
- idle, or in its second-to-last execution cycle.
- in the third through eighth execution cycle (EX+2...EX+7)
of a DIV.S
- in the third through twenty-first execution cycle
(EX+2...EX+20) of a DIV.D
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