fmadn

speculable  exu stream  exu block  compute phase   operation   in the decimal floating point value domain   and rounds toward negative infinity

native on: Decimal8 Decimal16

Decimal floating point fused multiply-add. As usual for those, it yields a higher precision than doing it separately, and is faster too. Rounds towards negative infinity.

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fmadn(d x, d y, d z) → d r0

operands: like Addd [dd:d]

Returns x*y+z on the belt.

encoding: fmadn(d x) , exuArgs(op arg0, op arg1)

Core	In Slots	Latencies
Decimal8	E0 E1	d,d:d=7 dv,dv:dv=7 q,q:q=8 qv,qv:qv=8
Decimal16	E0 E1	d,d:d=7 dv,dv:dv=7 q,q:q=8 qv,qv:qv=8

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fmadn(d x, d y, d z, d w) → d r0, d r1

operands: like Fmasd [dd:d]

This is a fused multiply-add-subtract. An excellent way to make full use of all Functional Units in the 2 Slots.
r₀ is x*y+z*w
r₁ is x*y-z*w

encoding: fmadn(d x, d y) , exuArgs(op arg0, op arg1)

Core	In Slots	Latencies
Decimal8	E0	d,d:d,d=7,7 dv,dv:dv,dv=7,7 q,q:q,q=8,8 qv,qv:qv,qv=8,8
Decimal16	E0	d,d:d,d=7,7 dv,dv:dv,dv=7,7 q,q:q,q=8,8 qv,qv:qv,qv=8,8

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