AMCC Proprietary 286
Revision 1.02 - September 10, 2007
PPC405 Processor
nmacchw
Negative Multiply Accumulate Cross Halfword to Word Modulo
Preliminary User’s Manual
nmacchw
Negative Multiply Accumulate Cross Halfw ord to Word Modulo Signed
nprod
0:31
← –((RA)
16:31
x (RB)
0:15
) signed
temp
0:32
← nprod
0:31
+ (RT)
(RT)
← temp
1:32
The low-order halfword of RA is multiplied by the high-order halfword of RB. The negated signed product is
summed with the contents of RT and the sum is stored in a 33-bit temporary register. The contents of RT are
replaced by the low-order 32 bits of the temporary register.
Registers Altered
•RT
• CR[CR0]
LT, GT, EQ, SO
if Rc contains 1
Architecture Note
This instruction is part of the Multiply-Accumulate instruction set extensions and complies with the architectural
requirements for APUs of the PowerPC Embedded Environment. As such, it is not part of the PowerPC Architec-
ture, nor is it part of the PowerPC Embedded Environment. Programs that use this instruction may not be portable
to other implementations.
nmacchw RT, RA, RB OE=0, Rc=0
nmacchw. RT, RA, RB OE=0, Rc=1
nmacchwo RT, RA, RB OE=1, Rc=0
nmacchwo. RT, RA, RB OE=1, Rc=1
4 RT RA RB OE 174 Rc
0 6 11 16 21 22 31
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