IBM PPC440X5 Uživatelský manuál stáhnout pdf (Strana 355)

100

101

maclhwsu

Multiply Accumulate Low Halfword to Word Saturate Unsigned

Preliminary PPC440x5 CPU Core User’s Manual

instrset.fm.

September 12, 2002 Page 355 of 589

maclhwsu

Multiply Accumulate Low Halfword to Word Saturate Unsigned

prod

0:31

← (RA)

16:31

× (RB)

16:31

unsigned

temp

0:32

← prod

0:31

+ (RT)

(RT)

← (temp

1:32

∨

temp

)

The low-order halfword of RA is multiplied by the low-order halfword of RB. The unsigned product is summed

with the contents of RT.

If the unsigned sum can be represented in 32 bits, then RT is updated with the low-order 32 bits of the

unsigned sum.

If the unsigned sum cannot be represented in 32 bits, then RT is updated with a value which is “saturated” to

the maximum representable value of 2

–1.

Registers Altered

•RT

• CR[CR0] if Rc contains 1

• XER[SO, OV] if OE contains 1

Architecture Note

This instruction is implementation-specific and programs which use this instruction may not be portable to

other PowerPC Book-E implementations. See Instruction Set Portability on page 250.

maclhwsu RT, RA, RB OE=0, Rc=0

maclhwsu. RT, RA, RB OE=0, Rc=1

maclhwsuo RT, RA, RB OE=1, Rc=0

maclhwsuo. RT, RA, RB OE=1, Rc=1

4 RT RA RB OE 460 Rc

0 6 11 16 21 22 31

1 2 ... 350 351 352 353 354 355 356 357 358 359 360 ... 589 590

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